Molecular electronics that can produce functional electronic circuits using a single molecule or molecular ensemble remains an attractive research field because it not only represents an essential step toward realizing ultimate electronic device scaling but may also expand our understanding of the intrinsic quantum transports at the molecular level. Recently, in order to overcome the difficulties inherent in the conventional approach to studying molecular electronics and developing functional device applications, this field has attempted to diversify the electrical characteristics and device architectures using various types of heterogeneous structures in molecular junctions. This review summarizes recent efforts devoted to functional devices with molecular heterostructures. Diverse molecules and materials can be combined and incorporated in such two‐ and three‐terminal heterojunction structures, to achieve desirable electronic functionalities. The heterojunction structures, charge transport mechanisms, and possible strategies for implementing electronic functions using various hetero unit materials are presented sequentially. In addition, the applicability and merits of molecular heterojunction structures, as well as the anticipated challenges associated with their implementation in device applications are discussed and summarized. This review will contribute to a deeper understanding of charge transport through molecular heterojunction, and it may pave the way toward desirable electronic functionalities in molecular electronics applications. The authors present recent advances to develop a wide spectrum of molecular heterostructures, as well as their prospects and applicability. Various molecular heterostructures and their novel electrical characteristics, along with their charge transport mechanisms are presented. In addition, the potential applicability, merits, and perspectives, as well as the anticipated challenges associated with their implementation in electronic device applications are discussed. For example, a silicon diode can be constructed using a heterojunction of n‐ and p‐type Si. Diverse heterojunctions, including Si/SiGe, Si/GaAs, and Si/InGaAs, have also been developed; these exhibit high carrier mobility and low‐power operation. In addition to this electronic application range, modern solar cells, sensors, and light‐emitting diodes (LEDs) have been extensively explored and proposed, based upon various forms of heterojunctions  as well as conventional semiconductor heterostructures. Moreover, for enhanced organic phototransistors (OPTs), incorporating additional materials  into the channel represents a well‐established method for enhancing photonic functionalities.Over the last half century, various types of functional devices have been built using semiconductor heterojunctions; these have laid the groundwork for the development of the modern electronics industry.5, 6Figure  In fact, since two‐ and three‐terminal junctions are the main passive and active device architectures in modern electronic goods, junction platforms for molecular electronics have also been designed in these shapes. The two‐terminal molecular junction structure employs only a sub‐1 nm single molecule or molecular SAMs placed between the top and bottom conductive electrodes ; this facilitates a unique charge transport mechanism that primarily depends upon the molecular structure itself and the contact geometry  and nano or micro via hole patterning through metal evaporation. These junction structures have been recognized as basic platforms for the characterization of single molecule or molecular SAMs and their intrinsic quantum transport properties. Meanwhile, three‐terminal molecular junction structures employ a solid back gate at the molecular nanogap junction  or an electrochemical gate (through ionic liquid) to the side of the single molecular junctions using STM  of the electrodes can be modulated by applying a gate‐induced electric field, thereby altering the overall charge transport across the molecule.Similarly, the field of molecular electronics has recently attempted to diversify the electrical characteristics and device architectures of various types of molecular heterojunction, by exploiting a combination of molecules and other nano or organic materials. Historically, molecular junction types, referred to as molecular homojunctions, have been classified into two‐ and three‐terminal junctions with a single molecule or molecular self‐assembled monolayer (SAM) , as shown in Figure 29 In y Figure . For dec memory, photoswitching, thermoelectric effects, and field‐effect transistors. However, these conventional types of molecular junctions suffer from several challenges, including tailored electrical functionalities and limited functional molecular components, operational stabilities, and junction yields. For example, various electrical functions and high performance may be restricted because charge transport is primarily determined by the energy levels of the molecular species. Furthermore, the general design principles for a molecular structure capable of exhibiting desirable electrical characteristics have not yet been concretely established, which could limit the applicability of molecular junctions. Electrical stability has also been a longstanding issue for these types of molecular‐scale junctions, because of their extremely low junction yield and high levels of operational unreliability and thermal fluctuation. In particular, the charge transport current in typical two‐ and three‐terminal molecular junctions varies significantly, despite minor variations in the contact geometry and surface morphology; this limits their utility as reliable electrical device units beyond charge transport studies. Consequently, developing a novel strategy and methods for overcoming these issues has emerged as the primary challenge in this field.Because both types of molecular junction allow for the use of countless molecular structure variables and facilitate the ultimate scale in high‐density integration, this field has attracted considerable attention for more than 50 years and has been extensively investigated using a variety of functional molecular species and junction structures. This endeavor has resulted in the realization of a variety of electronic functions in these molecular junctions, including diode,61 mem Essentially, a molecular heterojunction is composed of molecules and hetero units such as 2D or 3D semiconductors or nanomaterials; this facilitates the tailoring of various electronic functions and operational stabilities that are extremely difficult to achieve when using only molecules. In particular, 2D or 3D semiconductors with a certain bandgap structure can align hetero energy bands with a molecular band structure, thereby changing the charge transport pathways according to the electrical and junction variables. This could lead to a diversity of electronic functionalities in the molecular heterojunction form, as well as a well‐established junction structure that can be stably operated.Recently, with the development of fabrication technology and well‐tailored nanomaterial synthesis, molecular junction architectures designed to tackle these issues have been suggested and are becoming more diverse. Among these recent advances, various molecular heterojunctions in the two‐ and three‐terminal forms have been reported Figure . Numerou89 Ess For example, Xiang et al. provided an overview of molecular junctions at the level of the device platform and charge transport phenomena. Various molecular junction platforms and theoretical simulations were described in detail. Thereafter, they introduced the concept of integrating molecular functionalities into electronic circuits such as diodes, transistors, memory, and sensors. Jeong et al. presented various device platforms for high‐yield molecular junctions and their functionalities; here, distinctive electronic functionalities originated from the molecular structure and contact properties. They discussed an interlayer strategy and distinctive device fabrication procedure for high‐yield molecular devices. Lu et al. reviewed various micro/nanofabrication strategies for creating molecular junctions with a single molecule that enables desirable functionality. They discussed the difficulties and opportunities associated with the fabrication of single molecular devices. Lastly, Xie et al. presented various single molecular junction platforms for monitoring and manipulating the physical and chemical behavior of molecular components. They presented a summary of various dynamic investigations conducted at single‐molecular scale and discussed the open issues in this field. All of these reviews, however, have mainly addressed the traditional molecular junction structures  based on the metal‐molecule‐metal junction type first proposed by Aviram and Ratner in 1974. In contrast to previous reviews, we discuss recent advances made in efforts to develop a wide spectrum of heterogeneous structures in molecular junctions, as well as their prospects and applicability. In particular, various types of two‐ and three‐terminal molecular heterojunction structures and their novel electrical characteristics, along with their charge transport mechanisms are presented sequentially. In addition, the potential applicability and merits of molecular heterojunction structures, as well as the anticipated challenges and issues associated with their implementation in electronic device applications are discussed and summarized. This review departs from previous reviews in this field in terms of addressing heterogeneous structures in molecular junctions and their potential, and also offers a fresh perspective on how to advance this field further.Several progress reviews in the field of molecular electronics have been reported in terms of device platform, yield, and electrical functionalities.104 FoThe remainder of this paper is organized as follows. After the introduction Section , the mol2 The heterostructure is sandwiched vertically between the top and bottom electrodes. Diverse two‐terminal molecular heterojunctions have been investigated using STM, atomic force microscopy (AFM), and microscale via hole techniques. In these junctions, by incorporating 2D transition metal dichalcogenides (TMDs) or 3D  semiconductors, various hetero band alignments can be made; these can activate different charge transport pathways, depending on the molecular or semiconductor energy band structures, the molecular dipole moments and their directions, and the voltage polarities. In addition, by incorporating a functional nanomaterial  graphene), the device stability, yield, and junction transparency can be significantly increased; the last of these allows the device to be used as a molecular photoswitching junction platform.In Section 96 The2.1ΦM) by varying the interfacial potential drop.ΦM can be increased or decreased according to the directions of the molecular dipole moment, and its magnitude is determined by the difference in electronegativity between the metal–SAM interface and molecular backbone structure. Furthermore, the pinning effect at the Fermi level is alleviated because the SAM‐modified metal electrode has an almost dangling‐bond‐free interface. And, the non‐covalent or physical contact can be formed between molecules and organic semiconductor. Because of this effect, the interfacial transport barrier in the molecule‐organic semiconductor heterostructure can be determined by the offset between the Fermi level of the SAM‐modified metal and the conduction  band of the subsequent organic layer. In this sense, this junction structure creates an asymmetric hetero‐band alignment, facilitating the enhancement of rectifying features or optoelectronic properties via the selective blocking of electrons or holes. This method has frequently been employed to enhance the electrical properties of organic semiconductor devices. However, the molecular SAMs have only been used for interfacial barrier modulation, to improve the electrical performance of the organic electronic device; furthermore, the junction size is much larger than the molecular scale. Nevertheless, this strategy could offer a promising method and technological ground for implementing and understanding a functional molecular‐scale heterojunction, as will be discussed later.When molecular SAMs are formed on a metal electrode , their permanent dipole moment can modify the metal work function ΦM by vary They used a p‐type organic semiconductor, poly(3‐hexylthiophene) (P3HT). Several dithiocarbamate (DTC)‐ and thiol‐based molecular species were used, as shown in Figure Φ) of Au and Ag to ≈3.2 eV, as shown in Figure Φ values by molecular SAMs based on low kinetic energy photoemission threshold (secondary photoemission cutoff) in the ultraviolet photoelectron spectroscopy (UPS). Depending on the z‐direction magnitude of the molecular dipole moment (µz), Φ can be tuned over the range of ≈1.6 eV. A linear dependence of Φ on µz was also observed. To investigate the effect of the molecular SAMs and their dipoles on the device performance, electrical measurements of Au/molecular SAMs/P3HT/Au heterojunctions were performed  compared to the Au/P3HT/Au junction (black) (RR ≈ 1) (at ±3 V). However, in the Au/C8/P3HT/Au heterojunction (blue), the rectifying feature was not observed, though the current density (J) was approximately one order of magnitude lower than that of the Au/P3HT/Au junction (green). In the Al/P3HT/Au junction (green), the RR was found to be ≈2 × 104 and J was lower by three orders of magnitude compared to the Au/P3HT/Au junction. These findings can be explained on the basis of the following two considerations: 1) the effect of the molecular tunneling barrier and 2) the effect of the asymmetric hetero‐energy level alignments at both contacts on the transport conduction. First, the attenuation of J was primarily associated with the presence of molecular SAMs sandwiched between the Au and P3HT. The DTC‐1 and C8 molecules formed a tunneling barrier at the Au/P3HT interface, resulting in a decrease in J, as shown in Figure  In the case of the Al/P3HT/Au junction, the native oxide on the Al surface (AlOx) (with a thickness of ≈3 nm) caused a reduction in J. Second, the effect arising from the asymmetric hetero‐energy level alignment in the junction can be considered. Figures  This results in symmetrical electrical characteristics. However, for the Au/DTC‐1/P3HT/Au junction, the DTC‐1 monolayer can tune the work function of Au to 3.2 eV, closer to the lowest unoccupied molecular orbital (LUMO) level of P3HT. As a result, this junction establishes different contact barriers between the two interfaces, which rectifies the electrical properties  was significantly deeper than that of the bare ITO (−4.86 eV) and ITO/PEDOT:PSS (−5.15 eV) electrodes, owing to the molecular dipole moment  characteristics in the forward and reverse bias regions  of 26.53 mA cm−2, fill factor (FF) of 74.5%, and series resistance (Rs) of 2.47 Ω cm2 were improved compared to the bare ITO junction and ITO‐PEDOT:PSS junction. This is because the ITO‐2PACz electrode had a lower interface resistance than the ITO or ITO/PEDOT:PSS electrodes, resulting in a greater FF and overall PCE. Figure VOC) on the light intensity for the ITO, ITO‐2PACz, and ITO/PEDOT:PSS electrodes. The slope of ITO‐2PACz electrode showed 1.04 kT/q, significantly lower than that for the ITO electrode and the ITO/PEDOT:PSS electrode. A larger slope indicates that trap‐assisted recombination was significantly more involved. Therefore, ITO‐2PACz‐based OPV devices can reduce trap‐assisted recombination, leading to higher PCE and longer carrier lifetimes. Thus, the functionalization of 2APCz onto ITO can improve the functionality and stability of OPV devices by engineering the interface between the ITO and PM6 organic layers.Another example of molecule‐organic heterostructures has also been found in organic photovoltaic device applications. Lin et al. reported organic photovoltaic (OPV) devices using 2PACz (where 2PACz is [2‐(9H‐Carbazol‐9‐yl)ethyl]phosphonic acid) molecules as a hole‐selective transport layer (HTL) functionalized directly onto an indium tin oxide (ITO) anode Figure 3a.55[5S Figure . In addiS Figure . In addiS Figure .[56]4 Figure . Furthermore, the MCBJ technique based on silicon substrates may suffer from breaking of the gating electrode during the bending of the substrate (for separation of the source‐drain electrodes). To mitigate gate breaking, the electromigration process can be additionally used to aid in the formation of metal nanogaps. In addition to this, a single molecule FET with the MCBJ using nanometer scale noncontact side gate to the molecular junction or using a silicon membrane rather than silicon wafer had been suggested. For the STM‐BJ technique, the gate configuration is often composed of electrochemical gating with ionic liquid, which is useful for studying the charge transport behavior but has limitations for solid‐state molecular device applications. Moreover, junction platforms containing single or few molecules are vulnerable to thermal noise and fluctuations, even at room temperature. This places limits upon the operating conditions . To overcome these challenges and issues, a three‐terminal molecular heterojunction with lateral and vertical configuration using a single or bundle of molecules and graphene has recently been suggested as a novel type of molecular transistor.However, these three‐terminal molecular junction platforms suffer from several challenges. Owing to the complexity of the device fabrication processes and the difficulty of obtaining precise 1‐ to 2‐nm‐wide electrode nanogap separation, the electromigration and MCBJ techniques have resulted in a low device yield.100 FuIn this section, we discuss the recently reported three‐terminal molecular heterojunction structures composed of a single molecule or molecular SAMs and graphene, as well as their main electrical characteristics under lateral and vertical configuration. In these device structures, a single (or a few) or molecular SAMs are commonly placed between graphene nanogap or a single layer of graphene (source) and bottom Au (drain) electrodes. A dielectric layer connected to a gate electrode was back‐gate structure or vertically stacked on top of the graphene layer, as shown in Figure π–π stacking interaction between molecules and graphene can give stability up to high temperature compared to conventional nanogap‐based molecular junctions, as discussed previously. In addition, since the graphene electrode is extremely thin, the interfacial coupling between molecule and gate field can be enhanced by reducing the screening of an applied gate‐field. Hence, it can highly be likely to exhibit a reliable gate tunable electrical characteristics by modulating the molecular frontier orbital level.For the three‐terminal lateral molecule‐graphene heterojunction ‐1,6‐heptadiene‐3,5‐dione) (9Accm)  as an electrode to exclude the gating effect of graphene electrode. When the molecular junction formed, the changes in the I–V characteristics are observed  Figure . The antd Figure . Accordid Figure . The gatEF for graphene in the electrostatic field. In addition, the unshielded partial electrostatic field achieved by graphene could directly tune the energy level of molecular SAMs or change their redox states, resulting in effective conductance modulation in the device. As a result, in comparison to typical three‐terminal molecular junctions, this three‐terminal vertical molecular heterojunction can be operated reliably at room temperature with a high yield and can also be used to modify the redox state of molecules and the transport barrier in the presence of a gate electric field.For the three‐terminal vertical molecule‐graphene heterojunction phenyl)ethynyl)‐p‐cyclophane (PCP) or 1,4‐bis(((4‐acetylthio)phenyl)ethynyl)benzene (OPE3) molecules on patterned Au (source)/SiO2/highly doped Si substrates  varies from −1 to 1 V for three‐terminal PCP‐ and OPE3‐graphene heterojunctions, respectively. VG can shift both the graphene energy level and molecular orbital level with regard to the EF of Au. In other words, when a positive (negative) VG is applied, the EF of graphene is shifted upward (downward), and the positions of the HOMO and LUMO in the molecular SAMs are shifted downward (upward). When a positive (negative) VD is applied under VG > 0 (VG < 0), the Fermi level approaches the Dirac point of graphene, resulting in the movement of conductance minima in the positive (negative) VD direction  on an Au/highly doped Si substrate (source) and transferred CVD‐grown single‐layer graphene (drain) on top of the SAM  oxidation  between the graphene and Fc moiety  as a function of the contact length (d) and N . The d corresponding to the minimum EGround for N = 0 and −1 was changed from 3.2 to 3.8 Å, affecting the conductance of the molecular junction. Figure DV−DI curves for different d. They speculated that the lower conductance of the EC oxidation in Figure + condition) might be due to the increase in d under a positive VG.In addition to this, using the same molecular vertical transistor configuration, Jia et al. also fabricated a three‐terminal molecular redox‐switching device.210 Thn Figure . Becaused Figure .[211,e Figure . In the n Figure . On the n Figure . Figure y Figure , by chanTo summarize, graphene‐based vertical molecular heterojunction structures offer a novel strategy for fabricating molecular vertical transistors with good stability, reliability, and high yield. In addition, the molecular redox response can be controlled by electrochemical gating effects, to provide a switchable molecular heterojunction platform. Graphene‐based vertical molecular heterojunctions represent promising candidates for molecular‐scale transistors and novel electrical functionalities in molecular‐scale heterojunction structures.4 Furthermore, this effect can vary depending on the molecular characteristics ; that is, it could be used to engineer the energy level alignment of subsequent hetero units . As a result, it has the potential to control charge transport characteristics in heterojunction systems and generate novel electrical functionalities. Another merit of molecular heterostructures is that there are numerous heterogeneous material combinations and variabilities. Diverse hetero‐units can be combined and included in this junction to implement desirable electronic functionalities. This diversity in hetero units allows the rational design of electronic functions to be extended. These strategies and attempts differ from those of conventional molecular homojunction systems and have the potential to broaden the field of molecular electronics by diversifying the electronic functionalities and novel junction structures. Also, the heterojunction system can significantly improve the device yield and produce excellent operational stabilities, owing to the existence of a subsequent hetero unit after molecular SAMs. This hetero unit effectively prevents the top metal from penetrating the molecular layer, passively and effectively protects the junction from the external environment, and is capable of stabilizing under repeated programming inputs and thermal effects. In addition, those functions and roles of the hetero unit can also increase the degree of integration in both two‐ and three‐terminal vertically stacked molecular heterojunction devices, which can raise the possibility of electronic applications. This is because the molecular SAMs can be encapsulated and protected against environmental factors by hetero‐materials unit, avoiding oxidation and metal penetration under fabrication process. Since the device density can be determined by the cross‐sectional area between the top and the bottom electrode, fabrication methods for decreasing the junction area is necessary. Recently, Kwon et al., made a well‐defined single vertical truncated conical nanopore structure less than 10 nm based on a simple CMOS‐compatible manufacturing process. This method for creating a single nanoscale pore could be implemented in vertical two‐ and three‐terminal molecular heterojunction platforms containing a few tens of molecules, thereby significantly increasing device density. In the lateral molecular heterojunctions based on a single molecule and graphene, the ultimate scale of molecular heterojunctions can be realized. Compared to lateral molecular homojunction, the π–π stacking interaction between molecules and graphene can improve stability up to high temperature. Recently, there is developed a technique that makes uniform nanogap < ≈1 nm between metal on a 4‐in. wafer using the CMOS‐compatible atomic layer lithography technique. This technique, which can precisely control the sub‐1 nm gap at the wafer scale, could be used as a platform for FET device for laterally connected molecular heterojunctions. To summarize, these molecular heterojunction systems exhibit considerable potential in terms of tailored electronic functions facilitated by interfacial energy band engineering, numerous heterogeneous material combinations, high device yield, high integration degree, and stability. Given that all of these are related to the long‐standing challenges of conventional solid‐state molecular junction device forms, molecular heterojunction systems have considerable potential for realizing molecular‐scale electronic devices. To summarize various molecular heterojunctions with different hetero units and device structures, we summarized molecules (single or SAM), hetero units, thickness of hetero units, junction scheme, functions, performance, and device yield in Table This section summarizes and discusses the applicability and merits of molecular heterojunction structures as well as the anticipated challenges and issues associated with their implementation in electronic devices. As mentioned previously, a single molecule or molecular SAMs can create a permanent dipole moment with a strong electric field. This abrupt potential change at the molecular scale can be utilized to tune the energy levels of the metal or semiconductor surfaces.213 FuNonetheless, significant obstacles remain in establishing a genuine molecular electronic heterojunction with desirable electrical and device performances. First, compared with conventional molecular homojunctions, the level of difficulty for device fabrication is significantly increased. Because the fabrication of the molecular heterojunction often requires an additional step to laterally locate the molecules between hetero units, or vertically stack the subsequent hetero unit on or under the molecular SAMs, the fabrication complexity can be further increased; this could lead to unexpected effects such as damage to the molecular layer or non‐uniformity of the heterostructure regions. As the difficulty of fabrication increases, large‐scale mass manufacturing for commercial applications will become more difficult. The second obstacle is the complexity of charge transport mechanisms through the heterostructure. Because the molecular heterojunction system is composed of a combination of a single molecule or molecular SAMs, and organic, inorganic, or 2D nanomaterials, charge transport through these heterostructures may be difficult to comprehend within the standard frameworks typically used for inorganic‐based heterostructures or molecular homojunctions. Given the fact that the transport mechanisms of molecular junction  have remained a controversial issue and have been studied by many research groups around the world for decades, it seems very difficult to develop solid theoretical models to fully understand the charge transport properties of various molecular heterojunctions. Third, different technical issues arise, depending on the heterostructure types. For the molecule‐organic heterojunction systems, a second organic layer is typically formed by the spin‐coating process. Owing to the difficulty in filling the organic material via a nanoscale hole, this method may impose constraints on the formation of a nanoscale junction. Furthermore, because the thickness of a coated‐organic layer is on the order of hundreds of nanometers, the effect of molecules in the heterostructure upon the electronic characteristics may be limited. In molecule‐inorganic 3D semiconductor heterojunction systems, molecular SAMs are directly formed on inorganic 3D semiconductors. However, a limited number of molecular anchoring groups are capable of chemically attaching to inorganic semiconductors, which limits the variety of heterostructure combinations. Additionally, because the inorganic hetero unit is positioned beneath the molecules in this type of molecular heterojunction, it is difficult to prevent top metal penetration when fabricating a solid‐state molecular device. This could lead to low device yield and operational instability. Molecular‐2D material heterojunction systems have many strengths in terms of the fabrication of molecular‐scale junctions, implementation of electrical functions, and device yield and stability. However, challenges remain in terms of large‐scale, high‐quality 2D nanomaterial growth and direct transfer onto molecular SAMs. These issues may impede the fabrication of molecular‐scale heterojunction devices on a large scale and may also increase the cell‐to‐cell deviation and junction non‐uniformity. Therefore, the degree of advancements in the growth and fabrication of 2D nanomaterials could significantly affect the development of molecular electronics.5The field of molecular electronics has seen significant growth in the last half‐century owing to developments in nanofabrication technology and theoretical calculation capabilities. The original goal of implementing a wide variety of electronic functions derived from molecular structures has received significant attention from the perspective of pursuing the ultimate nanoscale electronic devices. Additionally, because molecular building blocks possess infinite degrees of freedom in terms of molecular structure, the growth potential of molecular electronic components remains substantial. Many molecular homojunction platforms have been specially devised and designed to gain a better understanding of the intrinsic charge transport mechanisms via single and molecular SAMs layers, and their electronic device applicability has been thoroughly evaluated. Numerous critical variables governing the electronic behavior and quantum transport in molecular junctions have been identified and investigated. Although our understanding of and ability to fabricate molecular junctions has improved significantly, we are still confronted with significant challenges in implementing a robust molecular‐scale device with desirable electronic functionalities, as mentioned in the introduction. In this review, we introduced novel strategies and methods for overcoming these challenges, in terms of a variety of molecular heterojunction architectures. Diverse molecular heterojunction structures, such as molecule‐organic, molecule‐inorganic semiconductors (Si and GaAs), and molecule‐2D materials (graphene and TMDs) were sequentially presented, along with an explanation of the key parameters governing their electronic functions. As summarized in Section The authors declare no conflict of interest.


Cancer is one of the leading cause of morbidity and mortality worldwide. There are several therapies; however, most of them harm both healthy and cancerous cells. Proteolysis-targeting chimaeras (PROTACs) can be utilized as a targeted cancer treatment. These small molecules known as PROTACs are specialized, adaptable, and biologically active. Since PROTACs present a promising and alluring technology to solve off target and drug resistance problems in most cancers. They have the ability to trigger selective intracellular proteolysis, which can be utilized to specifically target and destroy tumor-promoting proteins inside of cells. To enhance their therapeutic outcomes, new understandings of the molecular mechanisms of PROTAC-mediated degradation are required.• Molecular underpinnings of PROTAC-mediated protein degradation• Modulation of the ubiquitination system for cancer treatment• Innovative designing and development of PROTACS-based therapeutics• Comparison of PROTACs with earlier non-targeted therapiesThe current Research Topic aims to explore the most recent developments in the creation and use of PROTACS-based treatments for cancer. We invite research articles, review articles, and viewpoints that speak to the following issues, but are not restricted to them.This Research Topic brings together several scientific contributions that highlight some extremely intriguing findings under its purview. The published articles on this topic have attracted significant interest from both academia and industry.Juan et al. have proposed methods to enhance their therapeutic efficacy and the development of fine-tuned nanoparticles based delivery systems to increase the bioactivity of PROTACs.The authors provided an overview of the current use of PROTACs to treat solid tumors and included recommendations for overcoming their clinical development roadblocks. Among designing and development constraints, improvements in bioavailability and safety brought about by an improved delivery route seem to be relevant. In light of this, Luo et al.). The emphasis of the authors has been on the molecular design of PROTACs using various methodologies, which provides a deeper mechanistic knowledge of developing degraders and serves as a beneficial roadmap for the advancement of the upcoming degrader technologies. Anwar et al. published a very thorough analysis of PROTACs designed to combat different forms of leukaemia and blood cancers. Along with all of this material, another investigation focused on how YAP1 deacetylation promoted chemotherapy resistance and targeted treatment in FLT3-ITD + AML cells . This research demonstrates that the FLT3-ITD + AML cells are maintained by the HDAC10-YAP1-PARP1 axis, by blocking this axis may improve the clinical outcomes for FLT3-ITD + AML patients.Significant developments in newly developed degrader technologies were also reported in this area (We anticipate that this study’s topic will offer readers an intuitive guide to understanding the current status of cutting-edge technologies like PROTACs, which can be employed as tools for targeted therapies and drug development.


F1 value of this model is about 10% higher than that of CopyRNN and CopyCNN.Keywords are usually one or more words or phrases that describe the subject information of the document. The traditional automatic keywords extraction methods cannot obtain the keywords which do not appear in the document, and the semantic information is not considered in the extraction process. In this paper, we introduce a novel Keyword Generation Model based on Topic-aware and Title-guide (KGM-TT). In the KGM-TT, the neural topic model is used to identify the latent topic words, and a hierarchical encoder technology with attention mechanism is able to encode the title and its content, respectively. The keywords are generated by the recurrent neural network with attention and replication mechanism in our model. This model can not only generate the keywords which do not appeared in the source document but also use the topic information and the highly summative word meaning in the title to assist the generation of keywords. The experimental results show that the  Keyword is the smallest unit to express the subject meaning of a document. It is widely used in tasks such as information retrieval, documents classification, and opinion mining . With thTo overcome the above drawbacks, some researchers had proposed a Sequence-to-Sequence model to solve the keyword generation task and had achieved some results, including seq2seq, CopyRNN , CorrRNNThe title is a highly purified and refined for the document, which can accurately reflect the nature, scope, and depth of the content of the document. Keywords are words that can express the characteristics of document subject content, and they play a similar and complementary role with title , so keywIn view of the fact that the existing extractive methods does not fully consider the semantics of context and the generative models ignore the guiding role of title, in this paper, we propose a Keyword Generation Model based on combination Topic-aware and Title-guide (KGM-TT). First, the neural topic model based on the variational autoencoder is used to generate the latent topic of the document and the hierarchical encoder with attention mechanism to encode the corpus; then, the circular neural network with attention copy mechanisms to decode the corpus coding and topic distribution for generating keywords. The KGM-TT model not only enriches semantic features by mining latent topics but also uses highly summative and valuable information in the title to jointly guide the generation of keywords.At present, there are many keyword extraction methods, which are mainly divided into unsupervised methods and supervised methods . For unsThe above extraction methods still cannot generate keywords that are not in the source documents. With the development of deep learning technology, a growing number of researches have been gradually evolving from keyword extraction to generative method . Liu et Keywords can represent the topics of a document. A document is usually composed of multiple semantic topics. Therefore, the extracted keywords should also cover all topics in the document. Li et al.  proposedSequence to sequence (seq2seq) model is a deep learning framework based on encoder and decoder. In 2014, Cho et al.  proposedThe traditional keyword extraction method cannot obtain the words that do not appear in the document. The existing generative methods ignore the guiding effect of document title on keywords and do not consider the subject semantic information of the document. The KGM-TT is a keyword generation model based on the fusion of topic aware and title guide, including neural topic model, title-guide hierarchical encoder, and topic-aware sequence decoder. The proposed KGM-TT integrates the semantic guidance of title words into the matching layer in the coding stage. The specific method is to use the attention mechanism to aggregate the title information for each word in the document content (Title-guide). In addition, in the decoding process, using the results of the trained neural topic model, a decoder with topic aware ability is improved to generate keywords with topic sensitivity (Topic-aware).The framework of KGM-TT model is shown in The neural topic model (NVDM-GSM) is used in KGM-TT is based on variational autoencoder (VAE). As shown in C={X1, X2, ⋯, XL} in corpus C as input, and process each document X into a BoW vector Xbow. Xbow is the V-dimensional vector on the vocabulary (V is the size of the vocabulary), input Xbow into the neural topic model and encode it into a continuous Gaussian variable Z (representing X's topic) by BoW encoder. Then the BoW decoder with Z as the condition reconstructs X and outputs a BoW vector Xbow′. The decoder simulates topic model's generation process. We then describe their division of labor.Specifically, the document BoW Encoder. Bow encoder is used to estimate a priori variables μ and σ, and σ is used to lead out topic representation Z. We adopt the following formula:f∗(·) is a neural perceptron with an RuLU activated function.BoW Decoder. Suppose that the attributive database C has K topics, and the topic vocabulary distribution of each topic in the vocabulary is represented by ϕK. For each document X ∈ C, there is a document subject distribution represented by θ . Specific to the neural topic model, θ is constructed by softmax functions. The generation process of documents in the decoder is as follows:Z ~ NDraw latent topic variable θ=softmax(WθTZ)Using softmax function construction topic mixture w ∈ X, w ~ softmax(WϕTθ)For each word, N represents the multidimensional Gaussian distribution, and σ2 is the diagonal of the covariance matrix. Wθ is the matrix of L∗K, L is the dimension of Z, and K is the number of topic. Here, it is used as the topic-word distributions . We adopt the topic mixture vector θ as the topic representation to guide keyword generation.Here As shown in de. Two bidirectional Gate Recurrence Units (GRU)  indicates the connection operation.The sequence decoder adopts a unidirectional GRU. On the general state update, the M and obtains key information through the attention mechanism. When predicting the j-th word in the keyword, the attention weight on wi ∈ Xseq is defined as αij′:vα, Wα, bα are trainable parameters and fα(·) indicates the semantic relationship between the i-th word and the j-th target word to be predicted. This relationship is also calibrated with the input latent topic information θ to explore and highlight the topic words. Thus, the topic sensitive context vector cj is obtained:The decoder decodes sequence cj, the j th word is generated on the vocabulary according to the following formula:In addition, under the condition of λj ∈  is used as a soft switch to decide whether to copy a word directly from the original text as the j-th target word.Wλ, bλ are trainable parameters and topic information θ is also injected here to guide the switch decision.A copy mechanism See et al.  is addedpj of the j-th target word can be predicted by using the following formula:αij′}i=1X|| serve as the extractive distribution over the source input.Finally, the distribution Our model KGM-TT is an end-to-end learning of latent topic model and keyword generation. First, the objective functions of the two modules are defined, respectively.p(Z) represents a priori distribution, q(Z|X) and p(X|Z) represent the process of BoW encoder and BoW decoder, respectively.For the neural topic model, the objective function is defined based on negative lower bound of negative variation, and its loss function is as follows:N is the number of instances of the training set and θn is Xn 's latent topics induced from GSM.For the keyword generation model, the minimum cross entropy loss function is used for training on all training sets:LGSM and LKG is used to define the training objectives of the whole framework:γ hyperparameters balance the effects of neural topic model and generative model.Finally, the linear combination of The two models are trained together and their parameters are updated at the same time. After the training, the beam search is used to generate the ranking list of keywords.https://www.cnki.net). It has 18,000 papers in total and includes 5,6589 words. These documents are papers published from 2000 to 2020, including the title, abstract content, keywords, and publication time of the paper. In order to reflect its good portability and achieve good results in large-scale data sets, the largest publicly available keyword generation data set KP20k built by Meng et al. [The corpus CNKI is crawled by our own crawler from China's largest scientific and technological publications databases  to measure the integrity of the model, and F1-measure to evaluate the performance of keyword extraction methods. To represents the keyword set provided by the dataset itself, Te represents the keyword set extracted by the model, and To∩Te represents the correctly extracted keyword set. Precision, Recall, and F1-measure are defined as follows:We use Precision (P) to measure the accuracy of the model, Recall  model without copy mechanism, sequence-to-sequence model with copy mechanism CopyRNN and CopyCNN. For the prediction of keywords that do not exist in the source text, since the traditional extraction methods cannot generate such keywords, the baseline models are CopyRNN and CopyCNN. For all baseline models, select the same parameter settings as Meng et al. .F1-measure values of the top 5 and top 10 predictions of each model are shown in For predicting the keywords existing in the source text, the keyword prediction ability of the above model on CNKI and KP20k datasets is compared. The F1@10 score) than the best generative model CopyCNN. Generally speaking, the recall rate (R) of the top 10 and top 50 predictions is engaged as an indicator to measure how many absent keywords are correctly predicted. The experimental results are shown in It can be found from the table that all the generation models are better than the traditional baseline method. In addition, it can be noted that the model proposed in this paper has significant advantages in both datasets. For example, on the KP20k dataset, our model improves 15.2% . In the process of encoding document words, it is guided by the title semantics. In the decoding process, a topic aware decoder is used. Therefore, the keywords generated by the KGM-TT are more subject-sensitive and higher quality. The experimental results show that the KGM-TT model proposed in this paper can make better use of the strong semantic information of the latent topic and title of the document. The KGM-TT is superior to other methods in keyword prediction, and can generate keywords with high accuracy. However, there are a large number of synonyms in the words generated by the keyword generation model. This is a problem that needs to be solved in our research in the future.


The dissemination of multidrug-resistant bacteria strains and genes carrying antibiotic resistance is currently considered to be one of the most important global problem. The WHO calls for the need to contain the spread of Antimicrobial Resistance (AMR) from all possible sources. There have been many international actions grouping scientists studying this phenomenon, and quite a lot of scientific projects devoted to this problem have already been carried out. As well, so far several strategies have been developed that can inhibit the AMR spread. In this mini-review, we highlight overlooked aspects that seem to be crucial for creating a comprehensive picture of AMR, especially in the context of One Health approach. JPIAMR is a global collaborative organization of 29 nations acting in accordance with One Health approach. The JPIAMR priority topics are diagnostics, environment, interventions, surveillance, therapeutics and transmission. Two of them are closely related to fate of AMR in the environment, namely “Transmission” and “Environment.” The “Transmission” aspect covers understanding and preventing AMR transmission, while the “Environment” topic deals with explaining the role of environment in persistence, selection and spread of AMR. By the end of 2021 JPIAMR supported 79 projects related to these two topics (see text footnote 1). Most of those projects were aimed at monitoring emerging pathogens in hospitals and their transmission into the environment (22 projects). Some other projects were focused on detecting ARB and ARGs among WWTP, livestock or aquaculture (20 projects), while 14 projects were aimed at developing new technologies to eliminate ARB or ARGs from manure, agricultural animals, aquaculture or water environments. Among all these projects, none aimed at explaining the role of the environment in the spread of AMR. Some factors promoting AMR spread are known, but plenty of determinants are still not well-understood. One of them is the impact of biodiversity on the antibiotic resistance spread. To explain the role of environment in AMR spread, an international project entitled ‘ANTIVERSA – Biodiversity as an ecological barrier for the spread of clinically relevant antibiotic resistance in the environment’ was launched. The project is supported by the Biodiversa European Partnership. In this mini-review, we are focusing on factors that influence AMR spread but are not commonly researched. To explain the role of the environmental aspects in the persistence, selection and spread of AMR a holistic approach should be taken.Spread of Antibiotic Resistant Bacteria (ARB) and Antibiotic Resistant Genes (ARGs) in the environment is now recognized as one of the top 10 global public health threats for humanity. In 2019 alone, about 5 million people worldwide died due to infections with multidrug resistant bacteria while undergoing treatment for various other diseases, and over a million people died after being infected with multidrug resistant bacteria. WHO calls for global action to counter dissemination of antibiotic resistance. Antimicrobial resistance (AMR) has become one of the main issues in the One Health strategy announced by the WHO. The One Health strategy recommends environmental monitoring and joint research carried out by specialists in public health, veterinary and environmental protection to stop the spread of AMR. So far, several strategies have been developed to inhibit the AMR spread. One of them is the Joint Programming Initiative on Antimicrobial Resistance, JPIAMR, launched in 2014. To date, JPIAMR has supported 99 projects and 38 networks gathering over 1,400 researchers by investing 125 million eurotetO, tetW, tetQ and intl1 persisted in soil manured with cattle feces, tetY genes in the same type of soil while The most obvious factor that promotes AMR spread in the environment are antibiotics responsible for the selection pressure . EnormouPseudomonas aeruginosa, methicillin in Staphylococcus epidermidis and tetracycline in Staphylococcus aureus and Actinobacillus actinomycetemcomitans , while blaTEM, blaCTX–M, mecA). Moreover, research showed that municipal biosolid-derived bacteriophages play a significant role in the transduction of resistance to cefoxitin and sulfamethazine. Transduction process was observed in an experiment performed with coliform bacteria isolated from agricultural soil incubated in the presence of subclinical concentrations of antibiotics and biosolid-derived bacteriophages , macB, and blaTEM were detected on MPs in freshwaters and sea waters  as a new factor promoting antibiotic resistance spread . The preronments . Clinicaa waters . Lu X. Ma waters . AlthougOne more group of factors responsible for AMR dissemination should be considered, namely soil properties and cultivation conditions. E. coli O157:H7 derivate strain added as invader to soil microcosms in laboratory conditions depended on the amount of soil bacteria. That strain was resistant to rifampicin  and kanamycin (ARG on MGE). In his study published in 2007, he used soil fumigation technique to obtain microcosms with modified microbial communities. Different depths of fumigation were applied, from 0h to 24 h. A progressive decline in numbers of invader was observed in unfumigated soil , while the survival of ARB in all fumigated soils was significantly enhanced. Similar results were obtained in research published in 2012 by van Elsas et al. where microcosms of sterile soil inoculated with a gradient of diversity present in serially diluted natural soil was used. The author noticed that among soil native microorganisms, bacteria with typical actinobacterial morphology were dominant. It is worth noting that other studies clearly showed that soil was markedly enriched in Actinobacteria after treatment with manure  or incubation time had no effect on ARG abundance in bacteriophages fraction. It is unclear why ARGs abundance in phageome neither increase after fertilization with manure nor decrease after manure treatment. Nevertheless, many on-going JPIAMR projects are focused on the use of bacteriophages to combat AMR, but it can be a big challenge to develop such environmentally safe technology. The existing gaps in knowledge about the impact of soil or water physico-chemical properties on AMR spread are also noteworthy. Recent research studies confirmed the correlation between soil type and soil properties, and ARGs abundance. Further studies with more comprehensive approaches will provide more detailed information about the factors promoting and limiting AMR spread.Natural ecosystems show variable resistance to invasion by ARB. It depends on many factors that should be taken into account in their entirety. Without proper understanding of the role of environmental factors that promote AMR spread our efforts will be useless. We have to take into account all the factors connected with AMR spread rather than focus only on any one of them. Regarding soil environment for example, not only biodiversity is important but also soil type, soil properties and cultivated crops. It seems that fertilizers  as well as used chemical plant protection agents are also important.Thus, comprehensive, interdisciplinary research studies are lacking that could provide broad results on dissemination of AMR in the environment, conducive to introducing new standards by the European Commission or governments of individual countries, concerning, e.g., the use of antibiotics in veterinary medicine, agriculture or animal farming and methods of wastewater treatment.AG-S: investigation, formal analysis, writing – original draft, and visualization. MP: conceptualization, writing – review and editing, supervision, funding acquisition, and project administration. Both authors contributed to the article and approved the submitted version.


Porous molecular materials are constructed from molecules that assemble in the solid-state such that there are cavities or an interconnected pore network. It is challenging to control the assembly of these systems, as the interactions between the molecules are generally weak, and subtle changes in the molecular structure can lead to vastly different intermolecular interactions and subsequently different crystal packing arrangements. Similarly, the use of different solvents for crystallization, or the introduction of solvent vapour, can result in different polymorphs and pore networks being formed. It is difficult to uniquely describe the pore networks formed, and thus we analyse 1033 crystal structures of porous molecular systems to determine the underlying topology of their void spaces and potential guest diffusion networks. Material-agnostic topology definitions are applied. We use the underlying topological nets to examine whether it is possible to apply isoreticular design principles to porous molecular materials. Overall, our automatic analysis of a large dataset gives a general insight into the relationships between molecular topologies and the topological nets of their pore network. We show that while porous molecular systems tend to pack similarly to non-porous molecules, the topologies of their pore distributions resemble those of more prominent porous materials, such as metal–organic frameworks and covalent organic frameworks. Porous molecular materials form bulk materials in the solid-state, in either crystalline or amorphous forms, with structures governed by the interplay of weak intermolecular interactions between constituent molecular components. Unlike extended porous materials, the porosity of a molecular material results from ‘extrinsic’ porosity, which is defined by the voids created by the inefficient solid-state packing of the molecular components . AlternaCrystalline, extended porous materials are often defined by their underlying topology, which describes the connectivity of the components of the network. The topological analysis of frameworks allows for a simplified categorization , and anaCC3 , a, ab) uril with two windows on opposite sides of the cylinder-like molecule arene molecules are packed in parallel columns with face-to-face orientation . Three tThese trends in packing arrangement broadly agree with the physical interpretation that usually more spherical molecules tend to pack in spherical close-packing arrangements with coordination number 12  or 14 (body-centred cubic packing), more elongated molecules (larger second momentum of inertia) tend to allow larger coordination numbers, and more regular and specific-shaped molecules  show less diversity of packings and tend to have coordination numbers similar to the number of faces, as they largely pack in a face-to-face fashion.bcu-x, fcu, gpu-x and 14T3—are found in all of the migration categories. When considering the local topology derived from only the strongest interactions, topological motifs of the well-known types 2C1, hcb, dia and  are most frequent. This further supports the notion that the topology of molecular packing is not directly determined by the window and pore sizes of porous molecules, but rather a key factor in determining the periodicity of migration pathways is observing differences in the relative orientations of windows with respect to each other.Comparing the molecular packing topologies for migration pathway categories 1, 2, 3 and 5 shows that the most frequent topologies—c,d and c show the dia topology of the strongest interactions, which is the same as the topology of the COP–COW net. In total, 141 of 162 (87%) structures with intrinsic pathways (category 1) have the same COP–COW topology as the network of strongest interactions. These COP–COW topologies are mainly constructed by the cages of 17 skeleton topologies, from which the types 2,3M10-1 (adamantane-like cages), 2M10-1 (pillar[5]arene derivatives) and 2,3M5-1 (three-sided lanterns) are most frequent. In 9 and 12 of the remaining cases, the intrinsic migration pathways are subnets and supernets of the COP–COW net, respectively. In category 2, the most frequent topological types are 2C1 and dia , bsn and srs) are also potentially interesting synthetic targets.It is interesting to note that the COP–COW nets, which describe the connection of intrinsic pores §3.4), in categories 2 (92 structures), 4 (8 structures) and 5 (62 structures) have the same topologies as those assigned to the molecular nets defined by only the strongest interactions (§3.2). Importantly, this suggests that there is a relationship between the packing topology of the strongest interactions and the topology of the intrinsic porosity found in our dataset of crystal structures. Furthermore, this relationship suggests that the strongest interactions (determined by a large solid angle or interaction surface area) favour a face-to-face (window-to-window) orientation of molecules. For example, figures 2.4, in ca and dia . In catedia net, composed of the tiles of the same topology, 64, as the 2,3M10-1 skeletons  can be fused by three 8-faces into a porous framework in ABIKUU or alternatively by two 6-faces into infinite tubes in ABILAB. However, due to partial fusing , the remaining faces are located on the surface of extrinsic pores  and cfc  [Rf = 3.73 Å, twice the size of the intrinsic channels (Rf = 1.70 Å). In these four structures , the geometrically most compatible 6-ring chair-like faces come into contact. These examples are similar to those of reticular chemistry in MOFs, where the co-crystallization strategy enables tuning of the intrinsic pore topology and extrinsic pore size.In this context, the face-to-face orientation of porous molecules is reminiscent of the tiling representation of porous networks  and assekeletons . 2,2,3M1ic pores . The COP ABILIJ)  and extrRw = 2.96 Å and Rp = 4.44 Å, has dia topology networks of strongest interactions and intrinsic pathways, which are similar to the networks seen in the structure OFOQOS, with Rw = 2.12 Å and Rp = 3.00 Å [Rf goes from 1.99 Å to 2.84 Å, and Ri goes from 2.91 Å to 4.37 Å in the structures UTEVOF and OFOQOS. An isoreticular relationship is found for UTEVOF and 29 other structures . Unfortunately, such a strategy is not always successful. Interesting counterexamples to isoreticularity in porous molecular systems and their pore structures are the four structures with cages of type 2,3M20-1 , where the sizes of the cages differ significantly, leading to different COP–COW nets: PIFHIY  yields a 3D 4,6-c fsc net, PIFKIB  gives a 3D 6-c bsn net, PIFWAF  gives a 1D 3-c , and PIFKEX (Rw = 3.79 Å), which has its windows open to extrinsic pores (Rf = 2.01 Å).In our case, the intrinsic pore sizes are defined by the porous cages themselves and can only be tuned by changing the size of the porous molecules. For example, the structure UTEVOF, made up of enlarged adamantane-like cages, with = 3.00 Å . The cor. 4We have used a series of material-agnostic definitions of topology to automatically analyse the topologies of molecular packing and pore networks in crystal structures of porous molecular materials. Our multi-scale topological analyses can be used to categorize porous molecular materials by their molecular skeleton topologies, local environments, crystalline packings and porous networks (or migration pathways). Using the underlying topological assignments to categorize porous molecules in our large dataset, we have explored the presence of structure–property relationships, and the extent to which isoreticularity holds, which may help guide future experimental endeavours. Unsurprisingly, the shape and external chemistry of porous molecular systems impacts their intermolecular interactions in subtle ways, leading to a delicate interplay between local and global structures, similar to that identified by a machine-learning investigation of molecular-based crystalline material porosity estimators . By consmolecules results in a variety of close-packed topologies such as bcu-x,tcg-x and gpu-x,fcu, very similar to that found for non-porous molecular crystals [pores (i.e. the pore topologies) yields a prevalence of pore topologies , featuring nets that are commonly found in MOFs (dia) and 2D-covalent organic frameworks (COFs) (hcb). The molecular packing of POCs is significantly determined by weak intermolecular interactions. Small changes to POCs, such as functionalizing linkers, may result in a different crystal structure, which may result in a different pore network. Therefore, any extractable ‘design rules’ are, necessarily, less strict observed correlations.We found that while there was not a one-to-one relationship between the size and identity of the porous molecule and topology of the molecular packing, considering the packing of the crystals . And consrs, dia and pcu migration pathways. 2D pathways, either hexagonal (hcb) or square planar (sql), are possible with all cage shapes, and 1D simple chains may result from lantern, adamantane and tubular cages, but are unlikely to form from cubic cage molecules. Overall, adamantane, cylinder, three-sided lantern and prism-shaped POCs are most likely to form crystals with intrinsic migration pathways.Nevertheless, we find that 3D migration pathways are possible with tubular, adamantane and cubic cages, which are likely to yield https://github.com/andrewtarzia/cage_collect/tree/master/pore_topologies) and then their net can be determined using ToposPro, in the same manner as one would determine the net of a MOF or COF. Comparing these two topological indicators can also be used to distinguish cases of polymorphism in POCs.Given a crystal structure of a POC, it is necessary to know two things in order to determine its likely use as an adsorbent: (i) the spatial arrangement of the intrinsic pores and (ii) whether molecular travel between those pores is possible. The spatial arrangement of pores is given by an analysis of molecular packing, undertaken here using ToposPro . Using oIn the future, our database could be expanded to include other materials classes, such as metal–organic molecular systems, which, given the different intermolecular interactions present, may yield a different distribution of nets. Additionally, a more rigorous and automated search of crystal-structure databases could provide a more diverse set of molecules.


This Research Topic of 20 review articles covers the incredible variety of molecular rotary nanomachines that have evolved over billions of years. The details of their molecular mechanisms are well-known for the Bacterial Flagellar Motor (BFM) and FoF1 ATP synthase/ATPase. They are inferred by analogy to the BFM for others: the 5:2 motors of gliding bacteria and the 5:2 motors of the Ton and Tol systems that govern events at the outer membrane of gram-negative bacteria. All of these systems couple a transmembrane ion motive force to useful work. Two additional articles consider the unique propulsion generator of the Archaea, the archaellum, which appears to be driven entirely by ATP hydrolysis and has an evolutionary history completely independent of those for the 5:2 motors and FoF1.This Research Topic originated with Mike Manson, who was inspired by the recently published structures of 5:2 rotary motors and the desire to create a fitting tribute to Howard Berg, who introduced rotary motors into biology. The effort was augmented by recruitment of Tom Duncan, Pushkar Lele, Jun Liu, and Beiyan Nan, who possess the expertise to select the authors best able to tell the story of rotary nanomotors and to edit their contributions.The Research Topic has six sections. The first two chapters serve as an introduction to the history, structure, and energetics of rotary motors driven by an ion motive force. The second of these provides a detailed consideration of the structure of 5:2 rotary motors and how their function and energetics compare with the Fo motor of ATP synthases, which has a gearing ratio ranging from 8:1 to 15:1 in different species. The next seven articles provide detailed reviews about different aspects and incarnations of BFMs. The following two articles discuss the function of ion-powered motors in gliding bacteria, which do not depend on flagella. Next, two reviews cover the Exb/Ton and Tol/Pal systems, both of which are driven by 5:2-type motors. As a segue into the FoF1 motors that drive ATP synthesis, the next two articles cover the archaellum, a helical propeller like the bacterial flagellum, but one driven by ATP hydrolysis rather than an ion motive force and possessing a completely different evolutionary trajectory. The last five articles review different aspects of what is known about the FoF1 ATP synthase, a crucial and ubiquitous energy-transducing enzyme that couples two rotary motor devices.The editors thank all 49 authors who generously agreed to put their collective knowledge about rotary nanomotors into words. They represent the leading research groups worldwide studying rotary molecular machines. The positive responses to our invitations were doubtless aided by the recognition that this was a tribute to the visionary insight of Howard Berg, whose paper with Robert Anderson in 1973 first declared that “Bacteria Swim by Rotating Helical Filaments.”We hoped that Howard would write an introduction to this Research Topic. Unfortunately, he passed away on December 30, 2021, just as it became clear that our vision was going to become reality. That sad event adds both poignancy and timeliness to this Research Topic. We also want to thank the four editors who supplemented the efforts of the five designated guest editors mentioned above and the 33 reviewers who, together with the guest editors, ensured that everything presented in the reviews was as clear, complete, and accurate as possible.We hope this Research Topic serves as a fitting tribute to Howard Berg, the unconventional intellect whose insight ushered in an entire field of molecular biophysics: the study of rotary molecular motors. Savor what is presented here and anticipate the new revelations which doubtless await in the coming years.All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


This will aid in the understanding of aortic aneurysm disease pathogenesis and insight into the pathways involved, and will thus facilitate early diagnostic analysis of aneurysmal disease. In this study, we reviewed these molecular imaging modalities and their association with aneurysm growth and/or rupture risk and their limitations. Furthermore, we outline recent pre-clinical and clinical developments in molecular imaging of AA and provide future perspectives based on the advancements made within the field. Within the vastness of pre-clinical markers that have been studied in mice, molecular imaging targets such as elastin/collagen, albumin, matrix metalloproteinases and immune cells demonstrate promising results regarding rupture risk assessment within the pre-clinical setting. Subsequently, these markers hold potential as a future diagnosticum of clinical AA assessment. However currently, clinical translation of molecular imaging is still at the onset. Future human trials are required to assess the effectivity of potentially viable molecular markers with various imaging modalities for clinical rupture risk assessment.Aortic aneurysms (AAs) are dilations of the aorta, that are often fatal upon rupture. Diagnostic radiological techniques such as ultrasound (US), magnetic resonance imaging (MRI), and computed tomography (CT) are currently used in clinical practice for early diagnosis as well as clinical follow-up for preemptive surgery of AA and prevention of rupture. However, the contemporary imaging-based risk prediction of aneurysm enlargement or life-threatening aneurysm-rupture remains limited as these are restricted to visual parameters which fail to provide a personalized risk assessment. Therefore, new insights into early diagnostic approaches to detect AA and therefore to prevent aneurysm-rupture are crucial. Multiple new techniques are developed to obtain a more accurate understanding of the biological processes and pathological alterations at a (micro)structural and molecular level of aortic degeneration. Advanced anatomical imaging combined with molecular imaging, such as molecular MRI, or positron emission tomography (PET)/CT provides novel diagnostic approaches for  Aortic Aneurysms (AA) are pathological dilations of the aorta, in which the diameter is enlarged to over 50% of its original size or over 30 mm , 2. DepeWhilst TAA has an estimated prevalence of 5.3 per 100,000 (0.0053%) within the Western world , AAA is Aortic aneurysms are fatal upon rupture and therefore life-threatening, elucidating the necessity of timely intervention. This has resulted in screening of moderate risk populations  in countries including England and Sweden, leading to a reduction in all-cause mortality , whilst Currently, AA patients are increasingly treated with minimally invasive, endovascular aneurysm repair (EVAR) which has become the standard of care for patients with suitable anatomy, as EVAR has substantially improved early survival compared with open repair , 24. HowThese limitations emphasize the need for additional and novel imaging techniques with increased accuracy for rupture risk assessment, that will allow for a more patient centered approach for elective repair. This review article will highlight the development of novel clinical imaging techniques based on molecular pathophysiological insights of AA development, within the pre-clinical and clinical settings, targeting aneurysm-specific biomarkers for better risk stratification and disease monitoring.Commonly used imaging techniques for monitoring AAs include ultrasound scanning (US), computed tomography (CT) and magnetic resonance imaging (MRI), all mainly aimed at determining the aortic diameter or volume. Although the diameter is a quick and relatively easy parameter to determine, its use is limited as it can give inaccurate measure in asymmetric aneurysms. For this reason, new imaging parameters such as aneurysm volume and aortic size index (ratio of aortic diameter and body surface area) are being explored within these existing techniques –33. US uComputed Tomography Angiography (CTA) can provide full 3D reconstructions of the aorta . While nMoreover, magnetic resonance imaging (MRI) has also been used for 3D visualization of the aorta. This technique essentially does not require a contrast agent. However, contrast enhanced magnetic resonance angiography  allows for additional imaging features and can provide useful information for the development of an AA such as 4D phase contrast , 39. ThiWith our growing understanding of the pathophysiology and molecular mechanisms underlying aneurysmal disease, novel targets for molecular imaging have become available.The aorta distributes oxygenated blood from the lungs to the systemic circulation. In order to facilitate the propulsion of blood from the heart to peripheral organs, the aorta possesses a high level of elasticity . Like otElastin and collagen are the main ECM proteins involved in pathological remodeling of the aortic wall upon aneurysm formation. Elastin is the main component of elastic fibers, which are organized into fenestrated sheets, or elastic laminae . ElasticDespite similarities in macroscopic appearance, TAAs and AAAs hold distinctly different underlying pathophysiological mechanisms. This can partly be attributed to the different embryological origin of cells from the thoracic and abdominal aorta . AdditioFBN1 and EFEMP2), transforming growth factor β (TGF-β) signaling (e.g. SMAD3 and TGFBR1/2) and cytoskeleton maintenance and motility (e.g. ACTA2 and MYH11) in patients, an autosomal dominant disorder with wide clinical variability affecting the cardiovascular, ocular and skeletal systems  in patients, characterized by systemic connective tissue abnormalities, including loose skin, lung emphysema, bone fragility, vascular tortuosity and aneurysms  . Heteroz systems . Homozygneurysms . Mutatio 123700) . These E 123700) –68. Cons 123700) , 70. DowTGFBR1/2 and SMAD2/3 encode proteins involved in TGF-β signaling and mutations in these genes cause Loeys-Dietz syndrome (LDS) in patients ; MIM 613795). LDS is characterized by arterial aneurysms, dissections and cardiac abnormalities  (Mutations in  607086) . The pro 607086) . DysfuncAs previously mentioned, AAA development is generally caused by a multifactorial process and cannot be attributed to a single cause. Risk factors for AAA development are smoking, advanced age, male gender, hypertension, and family history . DespiteAt the cellular level, hallmarks of AAA pathology include apoptosis of SMCs, ECM degeneration, inflammatory cell infiltration and oxidative stress . As descThus, several of these previously described processes are characteristic for TAA and AAA development and progression, respectively, and therefore are interesting targets for diagnosis and monitoring of disease in patients. As AAAs are often attributed to a convergence of multifactorial genetic causes combined with external factors, it is a lot more challenging to identify molecular mechanisms at play in each individual patient compared to TAA patients for which the single genetic cause and thus the associated molecular mechanism can be used as a target for molecular imaging. However, the majority of AA cases are abdominal , so therAneurysmal mouse models are used to test the effectivity of imaging techniques as disease development and progression are predictable and can be closely monitored. Mice have a fast reproduction rate, a short lifespan and are genetically similar to humans, and are therefore considered to be of value in medical research . MoreoveAneurysms in the thoracic part of the aorta typically result from degeneration of the aortic media with apoptosis of SMCs and elastic fiber degradation. Several genetic deficiencies resulting in TAA formation in patients, as described previously, have been mimicked in mouse models to study the underlying pathophysiological pathways  Figure .Fbn1mgΔ/mgΔ mice, with an in-frame deletion of exons 19–24 in the Fbn1 gene causing severe (ten-fold) reduction of Fbn1 expression , causing a four-fold reduction in normal Fibrillin-1 expression, were generated  was generated, causing AA formation in the ascending aorta (Fibulin-4 (Fibulin-4R/R)  . Fibulinfunction , 92. Thiassembly . FibulinTGFBR1/2 and SMAD3 genes in patients. Both Tgfbr1 and Tgfbr2 deletion cause embryonic lethality in mice due to severe defects in vascular development  or low-density lipoprotein receptor deficient (Lldr−/−) mice were initially used in research on atherosclerosis but were found to develop AAAs when being fed a high-fat diet , a hormone which increases blood pressure by promoting vasoconstriction and aldosterone secretion  or calcium phosphate (CaCl2 and PBS) to the adventitia of the aorta is another method to chemically induce AAA formation. This model induces elastin degradation, infiltration of inflammatory cells, angiogenesis and calcification of the aorta, subsequently resulting in AAA formation  inhibitor β-aminopropionitrile (BAPN) is a method to chemically induce both AAA and TAA formation in mice. BAPN causes medial disruption by blocking crosslinking of elastin and collagen, resulting in reduced stability of the ECM . It has These mouse models represent several important characteristics of human AAA development and therefore form interesting models for testing diagnostic and therapeutic markers. However, these methods are considered to be quite invasive to induce AAA formation and none of these models fully represent the natural progression of AAA growth in human patients. A complicating factor of pre-clinical testing in mice is that molecular pathways that are changed in these mice could be different, or not at all affected in patients, therefore impairing translatability. The fact that aneurysm development and progression is much faster in mice compared to the chronic AAA development seen in patients contributes to this concern. Difficulties in establishing a representative mouse model that mimics human AAA are attributed to the fact that in AAAs there is not one single cause of disease. Many risk factors such as smoking, age, weight and genetic variances are encountered during a long period of time and are hard to replicate in a model organism. Moreover, even a combination of all risk factors does not guarantee growth of an AAA. On the contrary, since TAAs are mostly caused by a single genetic defect, mouse models have been successfully created that represent important characteristics of TAA development in human patients. This makes these models more suitable for pre-clinical testing of imaging techniques targeting underlying molecular mechanisms of TAA development, since these are similar in mice compared to human patients.per se presents with limitations concerning translatability. The human and murine genome are largely similar, but not all physiological and pathological processes can be identically reproduced in mice. For example, distinct differences were found in response to inflammatory trauma in terms of gene expression , MRI and photo-acoustic imaging (PAI), are commonly applied to monitor AA development and progression in mice . The appCurrently, novel imaging techniques are being explored that apply molecular targeting of specific underlying pathways involved in AA formation and progression. Several of the previously mentioned mouse models have been used in pre-clinical trials to test these novel imaging techniques. Molecular targets that are under investigation for imaging applications with respect to AA formation include ECM proteins, MMPs, immune cells and SMC phenotype .ApoE−/− mice  . Followi−/− mice . Since tApoE−/− mice infused with AngII  compared to wild-type controls  was used to image AAA in th AngII . ESMA excontrols . When cocontrols . Gd-ESMAtic wall . Besidesure risk . Additio−/− mice . HoweverAdditional ECM proteins that have been shown to be upregulated in AAA tissue, and that might serve as suitable targets for molecular imaging, are thrombospondin, fibronectin and periostin , 137. ThApoE−/− mice . FXII is involved in thrombus formation and its expression and activity correlate with AAA size. Furthermore, inhibition of FXIIa (the active form of FXII) activity as well as FXII depletion inhibit dilation of the suprarenal aorta in AngII-infused in vivo visualization of MMP activation using fluorescence mediated tomography (FMT)-CT imaging. This probe was able to detect increased MMP activity even before aneurysms had formed in aortas of Fibulin-4R/R mice, proving its value as a predictive biomarker for TAA formation  MMP-specific tracer  MMP tracer, was used in CaCl2-induced ApoE−/− mice to enhance the SPECT image  probe MMPSense 680 targets MMP-1, MMP-2, MMP-7, MMP-9, MMP-12 and MMP-13 activity, enabling ormation . The MMPreatment . In a direatment , 148. Inreatment . The prec tracer . This stc tracer . The 99msed mice . 99mTc-RCT image . Increasvβ3, expressed on the cell-surface of monocytes and macrophages, using a 99mTc-cyclic arginine-glycine-aspartate (RGD) peptide tracer (NC100692) for μSPECT/CT has been proven successful in detecting vascular inflammation in a CaCl2-infused murine model of carotid artery inflammation  cytokines and proteases, which stimulate breakdown of the SMC layer . Macrophammation . This stysm size . This suarticles . MRI ana−/− mice . The iro−/− mice . Additio−/− mice . Combinein vivo imaging via the formyl peptide receptor 1 (FPR1), using the FPR1 ligand c-FLFLF labeled with either Cy7 to enable fluorescence imaging or 99mTc to enable SPECT imaging  were applied for simultaneous ultrasound imaging and drug delivery of a microRNA (miR-126), which downregulates VCAM-1 expression, in AngII-infused ApoE−/− mice  which is present on inflamed ECs and mediates accumulation and adhesion of leukocytes. VCAM-1 is upregulated in AAA and has been shown to play a role in the inflammatory response in aneurysms . Microbu−/− mice . This no99mTc-duramycin was developed to specifically target phosphatidylethanolamine (PE), which translocates from the inner to the outer cell membrane upon apoptosis , which accumulates in proliferating cells  PET/CT. 18F-NaF binds to calcium hydroxyapatite structures and correlates with AAA development and progression in AngII-infused ApoE−/− mice  positron emission tomography (PET) based on an st years . FDG-PETst years , 175. Inst years , a findist years , 177. Nest years , 179, anst years . Jalalzast years .18F-NaF (fluorine-18-sodium fluoride) that binds to calcium hydroxyapatite structures, has been studied in the clinic, demonstrating that high uptake is associated with aneurysmal disease and rupture/repair risk in humans too  in ex vivo human aortic tissue, as autoradiography demonstrated specific binding of 18F-Fluciclatide and 64Cu-DOTA-ECL1i to αvβ3 integrin and CCR2, respectively , all-cause mortality (P = 0.0635), and aneurysm-related mortality (P = 0.0590)  . However64Cu-diacetyl-bis (N4-methylthiosemicarbazone) (64Cu-ATSM) could be used for visualizing hypoxic cells in atherosclerosis in animal models  imaging agent l models , and recl models . Althougl models . Secondain vivo MMP imaging have yet been performed. Nevertheless, besides the fact that plasma levels of MMPs were demonstrated to be elevated in humans with AAA , albumin, and immune cells, have yet to be tested clinically for practical use. Emphasizing that a great leap remains to be made toward the transition of human trials to test for clinical validity.Contemporary imaging techniques for AA risk prediction rely on visual parameters such as the maximum aortic diameter. Although radiological methods have improved over the years, risk prediction for AA ruptures through imaging remains suboptimal, resulting in a one-size-fits-all policy for intervention while a more tailored patient specific approach is desirable. Murine models for TAA and AAA continue to provide us with an in-depth understanding of the pathophysiological pathways at a cellular and molecular level that are consequential to aortic degeneration and AA formation. With the advancement of technology, newer imaging techniques are capable of targeting these molecular pathways involved in disease progression, potentially allowing the determination of disease progression not only in mice, but also in patients. Interestingly, these clinical applications might in return also lead to more detailed understanding of pathophysiological processes.Within the pre-clinical setting, new potentially promising biomarkers such as collagen hybridizing peptide , targetiBesides the assessment of the predictive value of biomarkers, novel molecular imaging techniques mentioned in this review can be particularly valuable for pre-clinical testing of the efficacy of potential interventional therapeutics. Molecular imaging of elastin in mice treated with IL−1β neutralizing antibodies allowed the monitoring of the response to the inflammatory treatment, which reduced aneurysm expansion, besides the prediction of AAA growth and rupture . This shFuture studies will have to evaluate whether novel radiological techniques utilizing molecular biomarkers could be of routine use in clinical practice and provide us with a more accurate and personalized risk prediction for AA disease. At present, the clinical literature does not yet report a feasible molecular marker that is independently associated with AA risk rupture. Accumulation or degradation of specific ECM proteins, increased MMP activity and immune cell infiltration have been shown to be highly correlated with AA development, progression, and even rupture risk in the pre-clinical phase, and, therefore potentially hold a predictive value for more accurate risk assessment for surgical intervention in the clinic as well. In order to achieve clinical applicability, prospective human trials need to be initiated. Although few biomarkers have already proven their association with disease progression in a few initial studies, it remains of importance to assess the clinical viability by providing a significantly more accurate risk prediction of AA rupture.At first it will be essential to study which probes lead to highest sensitivity and specificity of rupture prediction within a given time frame. Pre-clinical studies already give insight into which markers could be most suitable. Specifically, probes targeting ECM proteins collagen and elastin as well as blood protein albumin were shown to successfully predict rupture risk in a mouse model of induced AAA. Furthermore, combined molecular imaging targeting elastin or collagen as well as immune cells showed superior results concerning AAA rupture prediction compared to molecular imaging of these targets individually. Markers such as MMPs and microcalcification hold predictive value concerning aneurysm growth, but whether they are also able to predict aneurysm rupture still has to be assessed. Thus, prioritizing translation of these markers is of utmost importance. Besides evaluation of independent molecular markers, future studies should assess the additional value of molecular imaging in which quantitative imaging analysis might play an important role. As AA development and progression is a multifactorial process, combined imaging of involved target molecules as well as visual parameters could provide us with a more comprehensive and complete view of the disease process and potentially allow for a more accurate risk assessment for AA development, progression, and even rupture risk. Leveraging computational methods and artificial intelligence that combine visual parameters with molecular imaging and the clinical presentation of the patient, shall potentially help lead toward even higher accuracy risk prediction of AA rupture. Furthermore, molecular markers that can be imaged with readily available imaging techniques in hospitals shall have a priority. Markers that need to be imaged with MRI, rather than by SPECT or CT, will be less practical due to the inherent time and cost of this imaging technique. As mentioned previously, ultrasound has been tested as theranostic molecular imaging modality within the pre-clinical setting, by utilizing microbubbles , 191. FuFurthermore, other technologies surrounding molecular imaging should be assessed. As previously mentioned, recent studies have demonstrated that the use of a dual probe in AAA murine models that concurrently target markers both in the processes of ECM degradation alongside inflammatory activity, leads to higher sensitivity (80%) and specificity (90–100%) of risk prediction , 134. AsVR, SS, JB, IP, and JE contributed to conception and design of the study. VR, SS, and JH wrote the first draft of the manuscript. HV, JB, IP, and JE wrote sections of the manuscript. All authors contributed to manuscript revision, read, and approved the submitted version.This work was supported by NWO-FAPESP project 457002001 .The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Salmonella (NTS) is a major cause of bacterial enterocolitis globally but also causes invasive bloodstream infections. Antimicrobial resistance (AMR) hampers the treatment of these infections and understanding how AMR spreads between NTS may help in developing effective strategies. We investigated NTS isolates associated with invasive disease, diarrhoeal disease and asymptomatic carriage in animals and humans from Vietnam. Isolates included multiple serovars and both common and rare phenotypic AMR profiles; long- and short-read sequencing was used to investigate the genetic mechanisms and genomic backgrounds associated with phenotypic AMR profiles. We demonstrate concordance between most AMR genotypes and phenotypes but identified large genotypic diversity in clinically relevant phenotypes and the high mobility potential of AMR genes (ARGs) in this setting. We found that 84 % of ARGs identified were located on plasmids, most commonly those containing IncHI1A_1 and IncHI1B(R27)_1_R27 replicons (33%), and those containing IncHI2_1 and IncHI2A_1 replicons (31%). The vast majority (95%) of ARGS were found within 10 kbp of IS6/IS26 elements, which provide plasmids with a mechanism to exchange ARGs between plasmids and other parts of the genome. Whole genome sequencing with targeted long-read sequencing applied in a One Health context identified a comparatively limited number of insertion sequences and plasmid replicons associated with AMR. Therefore, in the context of NTS from Vietnam and likely for other settings as well, the mechanisms by which ARGs move contribute to a more successful AMR profile than the specific ARGs, facilitating the adaptation of bacteria to different environments or selection pressures.Non-typhoidal  The accession numbers and metadata of each isolate are described in Table S1 (available in the online version of this article).The sequence data generated during the current study are available in the European Nucleotide Archive  is a major cause of diarrhoea worldwide and can cause invasive infections. Antimicrobial resistance (AMR) hampers the treatment of these infections and understanding how it spreads may help in developing effective strategies to combat it. This study describes NTS isolates from Vietnam using whole genome sequencing and phenotypic testing to determine what contributes to a successful AMR profile. We found concordance between most AMR genotypes and phenotypes but isolates from the same AMR phenotypes often had different AMR genes. Most AMR genes were found on a small number of plasmid types and in the vicinity of insertion sequences that allow AMR genes to be exchanged between plasmids and other parts of the genome. Our study demonstrates that for NTS from Vietnam, a successful AMR profile is defined by the mechanisms available for AMR genes to move rather than the specific AMR genes the bacteria contain.Non-typhoidal Salmonella (NTS) comprise the >2500 Salmonella enterica subspecies enterica serovars that are not associated with enteric fever , 12:b:- (n=2) in which no ARGs were identified, but this may be due to a small number of isolates investigated belonging to these serovars. Overall, 84 % of identified ARGs were encoded on plasmid replicon-containing contigs, compared to 1 % of virulence and 7 % of metal-tolerance genes. The majority of ARGs were located on contigs containing IncHI1A_1/IncHI1B(R27)_1_R27 (33%) and IncHI2_1/IncHI2A_1 (31%) replicon types. Plasmid contig groupings were complicated by those encoding multiple replicons, e.g., all contigs with the IncFIA(HI1)_1_HI1 replicon also had the IncHI1A_1/IncHI1B(R27)_1_R27 replicon, but not vice versa.ARGs have been found co-located with metal-tolerance genes and therefore exposure to heavy metals can co-select for AMR . ARGs haPan-genome analysis revealed that no ARGs were incorporated in the core genome (defined as presence in >95 % of isolates), compared to 65 % of virulence and 60 % of metal-tolerance genes. The metal-tolerance genes encoded resistance to 47 metals and antibacterial biocides; the NTS isolates investigated contained one or more core resistance genes associated with 36 of these compounds.n=1982) were found throughout the plasmid (n=678) and chromosomal (n=1304) sequences of the Salmonella genomes. In total, 98 % of ARGs were located within 10 kb of insertion sequences, compared to 7 % of virulence and 5 % of metal-tolerance genes. However, this insertion sequence analysis was complicated by some genes being in the vicinity of multiple insertion sequence types. Regardless of the genomic distance used as a cut-off (Appendix C) we confirmed that a larger proportion of ARGs were found in proximity to insertion sequences compared to virulence or metal-tolerance genes. IS6/IS26 comprised 21 % of all identified insertion sequences, but 95 % of ARGs were within 10 kb of this insertion sequence. Six ARG types were identified that were never associated with IS6/IS26, and five plasmid replicons were identified that were never found on the same contigs as IS6/IS26-associated ARGs. However, few copies of these ARGs (1-3) and plasmid replicons (1-5) were identified amongst the 68 NTS isolates investigated, preventing comparisons between specific ARGs, location and dissociation with IS6/IS26.Insertion sequences (P=0.04). However, two circular plasmids were identified that almost entirely (>99 %) consisted of PHASTER-predicted phage genome and both contained the pO111 plasmid replicon, making them phage-like plasmids. BLASTn found 79–80 % coverage between these plasmids and a phage P1 representative (NC_005856.1) , 12:i:- has acquired resistance to metals on en added . In addi [et al.  found vaAn aim of this study was to determine the contributing factors to a successful AMR profile, where success is defined as presence in multiple serovars, host species and disease presentations. Initially, successful AMR profiles were defined by phenotypic testing, with rare phenotypic AMR profiles defined as those found in three or fewer isolates from the OUCRU Vietnam collection and common (successful) AMR profiles in more than ten isolates of at least three different serovars and with resistance to at least three of the considered drugs. This study demonstrates that while some AMR profiles are common based on phenotype data, diverse underlying genetic mechanisms contribute to the phenotype. Therefore, at the resolution of genotype there are few common AMR profiles. In addition, long-read sequencing revealed the genomic context of the ARGs, showing that most ARGs were found on plasmids in association with IS6/IS26. This facilitates the movement of ARGs between plasmids and results in a large diversity of ARG profiles within plasmids. Therefore, in the context of NTS from Vietnam and likely for other settings as well, the mechanisms by which ARGs move between NTS contribute more to a successful AMR profile than the specific ARGs, allowing NTS to gain and lose ARGs in response to environments with different antimicrobial agents or other selection pressures.Klebsiella pneumoniae to identify the plasmids with which carbapenemase genes are associated [Pseudomonas aeruginosa to multiple species of Citrobacter via a plasmid [Campylobacter jejuni ST6964 in New Zealand, where a tetracycline resistance gene moved from a plasmid into the chromosome [Salmonella, here we have demonstrated the importance of plasmids and insertion sequences, but the mobile genetic elements responsible were not the same in the different bacterial species. Therefore, long-read sequencing of different bacteria from around the world and in many different ecological compartments is required to investigate the predominant mobile genetic elements responsible for AMR transmission.Long-read sequencing has facilitated ascertainment of the genomic location of ARGs, and therefore the evolutionary pathways of resistant organisms and likely routes of ARG movement. For example, it has been used on carbapenem-resistant sociated , and the plasmid . Long-reromosome . As withWe have demonstrated the large genotypic diversity underlying clinically relevant phenotypes. The greater resolution offered by identification of specific mechanisms of AMR and the genomic context in which they are found provides insight into the evolution and sources of AMR by identifying the most common vehicles of AMR within their population using an approach which can and has been applied in other settings . Here, tClick here for additional data file.