Although graphene has been widely used as a nano-filler to enhance the conductivity of porous materials, it is still an unsatisfactory requirement to prepare graphene-based sponge porous materials by simple and low-cost methods to enhance their mechanical properties and make them have good sensing and capacitive properties. Graphene platelets (GnPs) were prepared by the thermal expansion method. Graphene-based sponge porous materials were prepared by a simple method. A flexible sensor was formed and supercapacitors were assembled. Compared with other graphene-based composites, the graphene-based composite sponge has good electrical response under bending and torsion loading. Under 180° bending and torsion loading, the maximum resistance change rate can reach 13.9% and 52.5%, respectively. The linearity under tension is 0.01. The mechanical properties and capacitance properties of the sponge nanocomposites were optimized when the filler fraction was 1.43 wt.%. The tensile strength was 0.236 MPa and capacitance was 21.4 F/g. In cycles, the capacitance retention rate is 94.45%. The experimental results show that the graphene-based sponge porous material can be used as a multifunctional flexible sensor and supercapacitor, and it is a promising and multifunctional porous nanocomposite material. In recent years, porous materials have been widely used in superhydrophobic materials, adsorption materials, electronics, and other fields owing to their porous, loose, and flexible characteristics ,2,3. Con2 carbon atom with two-dimensional hexagonal crystal structure (HCC). Graphene is an ideal conductive filler for active materials of supercapacitors because of its strong ability to carry ions, hence it has attracted extensive research interest in the field of supercapacitors [In order to improve the conductivity and capacitance of porous sponge materials, conductive fillers are needed ,15. Amonpacitors ,30,31.The combination of porous materials and fillers will greatly improve the mechanical properties, electrical conductivity and capacitance performance, which is worthy of further exploration ,33,34. HIn this paper, a multifunctional flexible and conductive graphene-based sponge composite material is introduced. GnPs were prepared by thermal-sonication approach. The effects of different filler fractions on the mechanical and capacitive properties of nanocomposites were studied. The electrical responses of nanocomposites under different loading conditions such as tension, compression, bending, and torsion were tested. The electrical response of graphene sponge was measured when the temperature changed. GnPs synthesized by thermal expansion method are cheap and have good conductivity. The prepared sponge has good strength, sensing performance, and capacitance parameters. Graphene-based sponge composites have broad application prospects in multi-functional sensors and supercapacitors owing to their good versatility, easy production, and low cost.Asbury Carbons  kindly supplied graphite intercalation compound . The sponge made of melamine with the density of 15–17 kg/m3 was provided by Xijie Co . The porosity was 88.725% ± 0.53%. Na2SO4 was purchased from Tianjin Hengxing Chemical Reagent Manufacturing Co., Ltd. . All chemicals were used as received without any further purification. Scanning electron microscope (SEM) images of the graphene sponge were obtained by SU8010 . Transmission electron microscope (TEM) images of the GnPs were obtained by JEOL JEM-2100 . Raman spectra of GnPs were characterized by Raman spectrometer Avantes AvaRaman (The Netherlands). Tensile test measurement was performed using a uniaxial tensile loading machine LTD GX-SF001 . Fluke 2638A Hydra Series III Data Acquisition System  constantly monitored the resistance of the graphene sponge under different conditions. AnKe GDJS-408L high and low temperature test equipment is responsible for providing temperature environment for the change of resistance of graphene sponge with temperature. Capacitive properties of graphene sponge were analyzed using an electrochemical workstation ChenHua CHI660E B19038 . A piece of sponge (rectangular cuboids of 6.0 cm × 2.0 cm × 0.3 cm) was used as the matrix of the composite material. 2SO4 solution overnight. Then, a sandwich structure was created by combining the two electrode sponges, two pieces of platinum sheets as the current collectors, and a piece of filter paper as the separator.Two sponge electrodes (6.0 cm × 2.0 cm × 0.3 cm) were immersed in 1 M NaHeat treatment of graphite intercalation compounds (GICs) to produce thermal shock will immediately convert the intercalants into a large amount of gas, resulting in volume expansion. −1, 1584 cm−1, and 2723 cm−1, which correspond to D, G, and 2D bands, respectively. G band refers to sp2 resonance on an ordered graphitic lattice, while D band is activated from the first order scattering process of sp2 carbons owing to the presence of in-plane defects such as substitutional hetero-atoms, vacancies, grain boundaries, or other defects, which might be sp3 hybridized carbon structure associated with the quantity of impurity or oxidation degree.In The tensile strength and elongation at break of sponges with different filler fractions are tested. As shown in By testing the mechanical properties, it was found that the sample with 1.43 wt.% filler fraction obtained the best tensile strength and preferable elongation. Therefore, 1.43 wt.% samples were selected as the representative of the follow-up series of experiments.Signal linearity is an important parameter to measure when determining the sensitivity of materials. The cross-sectional area of graphene sponge decreases during tension, but owing to the special high elastic skeleton structure of sponge, the distance between conductive paths decreases and the paths become denser in the process of cross-sectional shrinkage. These factors lead to a decrease in the resistance of graphene sponges during stretching. As shown in The produced graphene-based sponge also possesses the ability of sensing deformations such as bending and twisting. Temperature is one of the factors that affect the conductivity of nanocomposites. The change of ambient temperature will cause the change of semiconductor or conductor sensing parameters. Therefore, it is necessary to study the electrical response of graphene sponge under temperature change. In this experiment, the temperature range was 25 °C~80 °C, and the temperature rise rate of the composite was 50 s/°C. It can be seen from The mechanical robustness and the distinctively porous structure of the graphene sponge imply that they have the potential to be used as electrodes for supercapacitor. The electrochemical performances of graphene sponge were studied using cyclic voltammetry (CV) and the galvanostatic charge/discharge (GCD) technique. All electrochemical measurements used two-electrode configuration, which can measure the cell performance more accurately.The CV curve of the 1.43 wt.% graphene sponge is much closer to the rectangle-like shape than the curve of the other two, and thus the curve has a larger area, representing the highest specific capacitance. This is because of the fact that sponges with high GnPs fractions have more conducting channels and inter-particle pores.EDLCs take important role in capacitance enhancement for the 1.43 wt.% graphene sponge. The specific capacitance values calculated from CV curves are 12.1, 13.8, and 16.7 F/g for the graphene sponge containing 0.47 wt.%, 0.94 wt.%, and 1.43 wt.% GnPs, respectively. The specific capacitance increases with GnPs filler fraction, because more GnPs create more electron pathways in the graphene sponge, leading to transfer of more electrons for electrochemical double layer capacitances.The performance of the 1.43 wt.% graphene sponge was specifically investigated at 20–100 mV/s. In The cyclic stability was measured for these graphene sponge electrodes. The capacitance decay was examined between 0 and 0.8 V at 0.5 A/g for 20,000 cycles. In conclusion, GnPs were synthesized by thermal expansion and peeling. A multifunctional graphene-based sponge nanocomposite was prepared by a simple method. By studying and optimizing the composition of graphene filler, it was found that the mechanical properties and supercapacitance of sponge nanocomposites were the best when the filler composition was 1.43 wt.%. Under 180° bending and torsion loading, the maximum resistance change rate can reach 13.9% and 52.5%, respectively. The tensile linearity is 0.01488. The maximum tensile strength was 0.236 MPa and the maximum capacitance was 21.4 F/g. The sponge nanocomposites developed have good sensitivity and electrical response under bending, torsion, and compression loads. It shows good performance in flexible sensor and supercapacitor applications. The electrical response of graphene sponge at different temperatures was investigated. There are no expensive materials or complex equipment used in the whole manufacturing process of nanocomposites. It is believed that this material has broad application prospects in engineering, electronics, and other fields.


The human papillomaviruses (HPVs) are a family of small DNA tumor viruses including over 200 genotypes classified by phylogeny into several genera. Different genera of HPVs cause ano-genital and oropharyngeal cancers, skin cancers, as well as benign diseases including skin and genital warts. Licensed vaccines composed of L1 virus-like particles (VLPs) confer protection generally restricted to the ≤9 HPV types targeted. Here, we examine approaches aimed at broadening the protection against diverse HPV types by targeting conserved epitopes of the minor capsid protein, L2. Compared to L1 VLP, L2 is less immunogenic. However, with appropriate presentation to the immune system, L2 can elicit durable, broadly cross-neutralizing antibody responses and protection against skin and genital challenge with diverse HPV types. Such approaches to enhance the strength and breadth of the humoral response include the display of L2 peptides on VLPs or viral capsids, bacteria, thioredoxin and other platforms for multimerization. Neither L2 nor L1 vaccinations elicit a therapeutic response. However, fusion of L2 with early viral antigens has the potential to elicit both prophylactic and therapeutic immunity. This review of cross-protective HPV vaccines based on L2 is timely as several candidates have recently entered early-phase clinical trials. Papillomaviruses also demonstrate a strict tissue tropism in that they only propagate in epithelia, and generally show a preference for either mucosa or cutaneous skin. Currently there are 226 known HPV genotypes catalogued in the Papillomavirus Episteme [https://pave.niaid.nih.gov/) [Papillomaviruses are small DNA tumor viruses with a range of malignant potential; most infections are benign and self-limiting but a ‘high risk’ group of HPVs are the etiologic agents of 4.5% of cancers worldwide . All papA genome . The papEpisteme  with manThe HPV genotypes of genus alpha predominantly infect the genital tract, but other mucosa including the anal and oral cavity are also susceptible. These HPVs are highly transmissible via sexual contact and as many as 60% of people who had sexual contact with an HPV infected person will acquire the virus . Of thesHPVs within the beta, gamma, mu and nu genera are mainly associated with benign infections of the squamous epithelia of cutaneous skin . The gamBeta HPVs typically produce only subclinical infections or flat warts. However, they are the subject of considerable interest as mounting evidence suggests the role of a subset of types as a co-carcinogen with UV light in the development of cutaneous squamous cell carcinoma (CSCC) ,18. ThisThe first evidence supporting beta types as causative factors in CSCC emerged from the identification of the genodermatosis epidermodysplasia verruciformis (EV). Patients with EV frequently develop persistent flat wart-like cutaneous lesions in childhood, and they often develop CSCC later in life in sun-exposed areas. Auto/hetero-inoculation experiments linked these lesions to beta HPV infection , and recpapillomaviridae is well-conserved and the 8 genes are expressed in a spatially and temporally controlled manner within squamous epithelia. There are six early genes E1, E2, E4, E5, E6 and E7 and two late genes L1 and L2, as well as a long control region (LCR) that serves as the origin of replication and to control transcription [The genome structure of the cription . E1 and cription .L1 and L2 encode the major and minor capsid proteins, respectively. Both L1 and L2 are expressed in the granular layer of epithelium, but they are not detectable in the basal epithelia that harbor the infection. Each HPV capsid is composed of 72 pentamers of L1, also known as capsomer(e)s. The capsomers associate to form a virion via disulfide bridges, i.e., 360 L1 proteins per virion. Additionally, there are estimated to be 12–72 L2 proteins per virion , but the®  and Gardasil® and Gardasil 9 ). Cervarix® is composed of HPV16 and 18 L1 VLPs produced in insect cells and formulated with alum and the TLR4 agonist monophosphoryl lipid A (ASO4 adjuvant system). In Gardasil, the aluminum hydroxyphosphate sulfate-adjuvanted VLP are expressed in yeast and derived from L1 of HPV 6, 11, 16 and 18 for the quadrivalent vaccine, and for the predominant nonavalent vaccine HPV31, 33, 45, 52, 58, as well. They induce high and durable titers of neutralizing antibodies as the structure of the particles allows for repetitive epitope display and favors hyperactivation of B cell receptors, and they are likely protective after only a single dose. Passive transfer studies in animal models suggest that these neutralizing antibodies are central to protection, likely acting in exudates at microlesions in the epithelium that are necessary for the viral inoculum to reach and infect the basal epithelia.Animal challenge studies demonstrated that vaccination with L1 VLPs provided robust, but type-restricted protection. However, L1 VLP vaccination did not impact pre-existing infection, likely because L1 is not expressed by infected basal epithelial cells. Currently, there are three licensed vaccines against Human Papillomavirus, all composed of L1-only VLPs derived from the most medically significant genotypes  and target a limited set of mucosal HPV types, albeit the most common in cervical cancer . Therapeutic vaccines aimed at treating pre-existing infections and disease generally target early antigens, primarily E6 and E7, as they are obligately expressed in infected cells and cancer, and are being developed to help those suffering HPV-related disease. It is clear that prophylaxis against a broader range of medically relevant HPV types is desirable for: (1) protection against all carcinogenic and probably carcinogenic alpha HPV that together cause >99% of cervical cancer and eliminate the need and costs for cervical screening, (2) protection against the morbidity and treatment costs associated with benign HPV diseases beyond genital warts, (3) protection against CSCC associated with beta HPV, especially in immunocompromised patients. Unfortunately, the number of different HPV genotypes that cause these diseases is large, rendering production of a sufficiently highly multivalent L1 VLP vaccine impractical, so development of a single cross-protective antigen is of interest as an alternative. For this, the field has generally focused on the minor capsid antigen, L2 (Graphic Abstract).The L2 protein is composed of ~500 amino acids and it is required for infection. L2, by itself, does not form the VLPs, but when co-expressed with L1, it co-assembles into capsids and facilitates the encapsidation of the viral genome . Most ofInterest in L2-based vaccination was re-kindled by two observations. First, vaccination with N terminus of the L2 protein elicits both neutralizing antibodies and protective immunity . Second,This hypothesis triggered renewed focus on defining the cross-protective epitopes displayed by L2 and how best to present them to the immune system to trigger a robust and durable immunity against the plethora of HPV types with significant medical impact (summarized in Graphic Abstract). These epitopes within L2 were defined by generating cross-neutralizing antibodies or by peptide vaccination. Examples include the identification of the RG1 cross-neutralizing monoclonal antibody which recognizes amino acids 17–36 of L2 ,43,44 F, or Mab5Neutralizing antibody titers are an important correlate of protection for prophylactic vaccines . Assay oSince vaccination of animals and patients with full-length L2 induced low titers of cross-neutralizing epitopes , one posLonger polypeptides can contain multiple protective epitopes and T helper epitopes. Vaccination with full-length L2 protein recombinantly expressed and purified from bacteria induces low levels of neutralizing antibodies and is protective. Cattle vaccinated with the N-terminal 11–200 polypeptide of the L2 of bovine papillomavirus type 4 (BPV4) showed stronger protection against BPV4 challenge and higher serum neutralizing antibody titers than animals vaccinated with the remainder or full-length L2 protein . VaccinaOne reason for the high immunogenicity of L1 VLP is repetitive display of the protective epitopes. Jagu et al. explored whether creating concatemers of the L2 protective epitopes, from 11–200, 11–88 and 17–36 would likely increase immunogenicity, and whether the number of repeats mattered by testing 3, 5, 8, 15 and up to 22 repeats . To incrAnother approach to increase the immunogenicity of multimers of protective L2 peptides is by insertion into a heterologous protein scaffold that itself activates T cell proliferation , such asThe above vaccines are formulated by mixing with a conventional adjuvant prior to administration, but improved immunogenicity might be achieved by direct conjugation of L2 to a defined adjuvant, such as a toll-like receptor (TLR) agonist. HPV16 L2 RG1 peptide fused with a broadly recognized T helper epitope (P25) and toll-like receptor 2 (TLR2) ligand dipalmitoyl-S glycerin cysteine (P2C) generated a potent response far superior to the linear epitope. Vaccinated mice were protected against challenge with HPV16 and HPV45. Sera from vaccinated mice neutralized other papillomavirus types, including HPV5 and BPV1 . This vaFlagellin is a TLR5 ligand that was tested as a direct fusion to multimer of L2 protective epitopes from various types  and was potently immunogenic at low doses without adjuvant . ImportaLactobacillus casei (L. casei)-expressing residues 1–224 of HPV16 L2 fused to the poly-γ-glutamic acid synthetase A (pgsA) surface protein were administered to Balb/c mice, they elicited neutralizing antibodies against HPV16 and other mucosal types including HPV18, 45, 58 and BPV1, but no protection studies were performed [Bacteria express several TLR ligands that could adjuvant an L2 vaccine response, and the use of lactobacillus as a vector for mucosal vaccines can promote strong responses . Lactobaerformed .E. coli form a pore in outer membranes. The L2 antigen inserted in OmpF was expressed in the E. coli and stably presented on the outer membrane, but the immunogenicity was not tested [As an alternative approach to provide surface display for L2 epitopes in the presence of TLR ligands, the outer membrane proteins (OMP) of a gram-negative bacterium that span membranes multiple times can be utilized, e.g., the trimeric OmpF in t tested .The L1 VLP vaccines induce high-titer antibodies even without adjuvant, and these responses are durable. This is believed to reflect the high density and close spacing of neutralizing epitopes that each particle displays  because this efficiently cross-links and activates B cell receptors, as well as promoting opsonization and uptake by antigen-presenting cells . By contHPV L1 is a logical carrier for the L2 epitope. Unfortunately, the cross-protective L2 epitopes are mostly buried in native virions or L1/L2 VLP and therefore do not effectively trigger an L2 response, which is why only L1 is used in the licensed VLP vaccines. Several groups began to identify potential insertion sites in L1 for conserved L2 protective epitopes, including residues 17–36, 65–81 or 108–120, by focusing on the surface loops ,101,102The DE loop of the L1-based VLP is particularly useful for such display, and it allows for the presentation of an antigen on the surface of the particles. One promising technology is a chimeric VLP that has an RG1 epitope derived from HPV16 displayed on the HPV16 L1 VLP surface . VaccinaIt is possible to use other L1 for display, including HPV18  or BPV1 However, while displaying a conserved L2 epitope on L1 VLPs elicits broad protection via induction of antibodies neutralizing for multiple HPV types that are not included in the vaccine, challenges remain. First, the L2-reactive titers, although associated with cross-protection, are low compared to the L1 VLP-specific responses. This raises concerns about the longevity of cross-protection induced by these HPV16L1–16RG1 VLP, although recent studies in rabbits show broad protection is maintained over 1 year using alum-formulated HPV16L1–16RG1 VLP . SecondlThe HPV16L1–16RG1 VLP (or similar such L2 chimeric construct) might be combined with a conventional multimeric L1 VLP vaccine to help fill in the gaps in coverage of hrHPV genotypes not directly targeted ,104. LikVLPs generated from the major capsid antigens of many other viruses have also been tested as carriers for surface presentation of L2 epitopes, including hepatitis B core virus-like particles displaying HPV16 L2 14–122 which induced HPV16 neutralizing antibodies , as wellAdeno-associated viruses (AAV) are small, single-stranded DNA paroviruses used in many human gene therapy studies. Their Rep genes code for proteins involved in viral replication and packaging while Cap genes code for structural proteins . When onReplication-incompetent adenovirus vectors have been widely tested as vaccines in humans, as they have proven safe and potent. Adenovirus type 5 (Ad5) hexon’s immunodominant neutralizing epitopes have been mapped to particular hypervariable regions (HVR). An L2 epitope comprising of residues 12–41 was inserted or substituted into HVR1 or HVR5 within the context of the virus by homologous recombination. The inclusion of the HPV L2 fragments did not affect the ability of the virus to replicate in 293 cells. Vaccination of mice, in which Adenovirus 5 cannot replicate, induced low neutralizing antibody titers against the L2 epitope as compared to the native virus, although the L2-specific antibody titers could be increased by an addition of adjuvants such as alum and monophosphoryl lipid A . This suVujadinovic et al. chose to display concatemers of L2 aa 17–36 epitopes from multiple HPV types at the C-terminus of protein IX of a rare human adenovirus type 35 (HAdV35) to allow incorporation of larger regions and to avoid issues of pre-existing immunity, respectively. This approach also leaves one end of the L2 unconstrained, perhaps better mimicking furin-cleaved L2 in the infectious intermediate . InsertiInstead of genetic insertion, another approach to coupling is the biotinylation of particles , in thisE. coli, or VLPs derived from the phage PP7 [Pseudomonas aeruginosa. In this study, the breadth of cross-reactivity of the L2 residues 65–85 was broadened by using a consensus sequence derived from hrHPV types to couple to the particles.Antigen display can also be accomplished either by genetic insertion or chemical conjugation of L2 peptides into the capsid surface of bacteriophage like Qβ, an ssRNA bacteriophage which grows in hage PP7 , an ssRNThe insertion of HPV16 L2 17–36 epitope into a surface loop (AB) displayed on a PP7 bacteriophage coat protein dimer allowed for proper VLP assembly without discernable changes to the PP7 morphology. Immunization of mice with these VLPs induced robust L2-specific antibody responses that neutralized and protected mice from vaginal challenge with either HPV16 or HPV45 pseudovirus . IntravaSince the goal is a single cross-protective construct, an alternative approach to unconstrained display of L2 at the N-terminus of the RNA bacteriophage MS2’s coat protein, to contrast with the presumably more rigid display of L2 within the AB loop of PPV7 coat protein, was tested. Amino acids 20–29, 17–31, 14–40 and 14–65 of HPV16 L2 were each genetically inserted at the N-terminus of the single-chain dimer of MS2 coat protein, and all assembled except for the 14–65 construct, suggesting a potential insertion size limitation. The MS2 VLP displaying HPV16 L2 17–31 elicited the broadest and most robust protection against vaginal challenge with diverse HPV genotypes . These pBreadth of cross-protection could also be further enhanced by incorporation of two epitopes into a single hybrid particle , or by tE. coli, and is administered as an amorphous antigen on alum. Phase I studies in healthy volunteers [The utility of L2 and L1 VLP vaccines is restricted to prophylaxis presumably because the basal keratinocytes that harbor the viral infection do not detectably express either capsid antigen, and therefore are not targeted, whereas the infected cells in the upper epithelial layers that do express them are already dying. Therefore, therapeutic ones targeting HPVs are being developed, and are frequently designed to target the viral oncogenes, E6 and E7, since they are obligately expressed in all HPV-infected cells . Other elunteers  and a phlunteers . In the lunteers . Both thCurrently licensed HPV vaccines offer prophylaxis against a limited range of HPV types, albeit the most common types in anogenital cancer, with low potential of cross-reactivity. It is not feasible to generate sufficiently multivalent L1 VLP vaccine formulations to cover all the oncogenic HPV types, let alone the many other benign types that cause considerable morbidity for patients. Therefore, there remains considerable interest in using an L2-based technology to vaccinate against most, if not all disease-relevant HPV types. This breadth of protection elicited by the well-conserved amino acid sequence of the protective epitopes of L2 may be especially important in immunocompromised patients such as organ transplant recipients and HIV co-infected patients who develop disease associated with a plethora of unusual HPV types.Although the L1 VLP vaccines produce high antibody titers, durable response and long-term protection, they do not have therapeutic potential. L2-based vaccines alone do not have therapeutic potential, but when fused with early proteins, notably the viral oncoproteins E6 and E7, they might induce both prophylactic and therapeutic immunity. This might be particularly advantageous for catch-up vaccination in older populations already exposed to HPV and thereby reduce cervical cancer rates sooner.There are many hurdles to the development of a broadly protective L2-based vaccine, including the success of the L1 VLP vaccines. Currently, the most challenging one is ensuring the longevity of L2-based immunity given the relatively lower neutralizing antibody titers than seen for the licensed vaccines, and the likely need for more than a single vaccination. However, it is important to appreciate that the neutralization assays detect protective L2 antibodies poorly, and that passive transfer assays are more informative .We have described the numerous L2-based strategies tested with a goal of achieving durable immunity, and virus-like display appears the most promising. However, immunity lasting over a year in animals has also been seen with repetitive display via L2 multimers formulated in alum or as a flagellin fusion. Furthermore, mice immunized with a single dose of MS2–16L2 VLPs were partially protected from challenge with a high dose of HPV16, one year after immunization even without the use of adjuvant . Single A particularly interesting emerging area of opportunity for L2 vaccination is in prevention of cutaneous squamous cell cancer (CSCC). Despite the use of sunscreen and costly screening and intervention by dermatologists , there a


Sarcoidosis is a systemic disease of unknown etiology, characterized by the presence of non-caseating granulomas in various organs, mainly the lungs, and the lymphatic system. Since the individualization of sarcoidosis-lymphoma association by Brincker et al., the relationship between sarcoidosis or granulomatous syndromes and malignancies has been clarified through observational studies worldwide. Two recent meta-analyses showed an increased risk of neoplasia in sarcoidosis. The granulomatosis can also reveal malignancy, either solid or hematological, defining paraneoplastic sarcoidosis. Recent cancer immunotherapies, including immune checkpoint inhibitors  and BRAF or MEK inhibitors were also reported as possible inducers of sarcoidosis-like reactions. Sarcoidosis and neoplasia, especially lymphoma, can show overlapping presentations, thus making the diagnosis and treatment harder to deal with. There are currently no formal recommendations to guide the differential diagnosis workup between the evolution of lymphoma or a solid cancer and a granulomatous reaction associated with neoplasia. Thus, in atypical presentations , and treatment-resistant disease, targeted biopsies on suspect localizations with histological examination could help the clinician to differentiate neoplasia from sarcoidosis. Pathological diagnosis could sometimes be challenging since very few tumor cells may be surrounded by massive granulomatous reaction. The sensitization of currently available diagnostic tools should improve the diagnostic accuracy, such as the use of more “cancer-specific” radioactive tracers coupled with Positron Emission Tomography scan. Sarcoidosis is a systemic disease of unknown etiology characterized by multiple granuloma formation in various sites, especially in the lungs, lymph nodes, liver, eyes, and skin . AlthougBacille de Calmette de Guérin (BCG) infection after instillation of BCG therapy for bladder cancer, or in case of cancer-specific treatments [anti-programmed death-(ligand)1 (PD-(L)1)/anti-cytotoxic T-lymphocyte antigen 4 (CTLA4)/anti-MAP/ERK kinase (MEK)/anti-B-Raf proto-oncogene (BRAF)] (https://www.pubmed.ncbi.nlm.nih.gov) using the keywords “sarcoidosis,” “cancer,” “lymphoma,” “sarcoidosis-lymphoma syndrome”, “sarcoid-like reaction” and “drug-induced sarcoidosis” that allowed us to find most of the references used to build this article.The occurrence of sarcoidosis or sarcoidosis-like reaction (SLR) in cancer patients has been known for several years, either through case reports or larger series –8. A loc (BRAF)] . Moreovep < 0.05)] and the risk of developing hematological malignancies was even higher  ] , 28. Lym1–2.62)] . Worth nIn a study about mortality in sarcoidosis patients in France, Jamilloux et al. reported that non-Hodgkin lymphoma was the most frequently declared cause of death in women when sarcoidosis was not the underlying cause of death, especially after the age of 50 . In anotn = 11), tuberculosis (n = 3), allergy (n = 1), disseminated annular granuloma (n = 1), atypical inflammatory bowel disease (n = 1), and undetermined granulomatosis (n = 4). Likewise, London et al. described a series of 39 patients with sarcoidosis occurring in the setting of lymphoma  along with dabrafenib, vemurafenib, trametinib, and cobimetinib (n = 37) , as well as BRAF/MEK inhibitors. SLR were described either with ICI . The So(n = 37) , 80. CorSarcoidosis has also been reported in hematopoietic stem cell transplant recipients. It was described either in allogenic –85 or auIn the past decade, TNFi were found to be an efficient way to treat sarcoidosis patients –92. The Sarcoidosis-lymphoma association was first described by Brincker in a series of 46 patients . In thisMost of the time, lymphoma occurs 2–8 years after the sarcoidosis diagnosis, preferentially in patients with a chronic course of the disease . CD4/CD8Sarcoidosis diagnosis requires three major conditions: (1) a compatible clinical/radiological presentation, (2) evidence of granulomas on a biopsy sample, and (3) exclusion of differential diagnoses .Although rarely observed, physicians should be aware that sarcoidosis can present itself as a pseudo tumoral condition such as miliary nodules, peritoneal involvement, and symptomatic osteolytic or osteoblastic lesions –104.Other red flags should alert the clinician about the atypical nature of sarcoidosis or the possibility of underlying neoplasia , 18-fluMagnetic resonance imaging (MRI) changes could also be helpful in distinguishing sarcoidosis lesions from tumoral localizations. Although conventional MRI is insufficient to distinguish malignant bone lesions from bone sarcoidosis , Conte eFinally, specific biomarkers have been proposed to ease the diagnosis, especially in germ-cell tumors. In such cases, the elevation of serum levels of α-fetoprotein, human chorionic gonadotropin and lactate dehydrogenase may help guide the diagnosis . No suggGranulomatosis and cancer can coexist in various clinical situations that the clinician should be aware of. The risk of developing solid neoplasia or hematological malignancies, especially lymphomas, is increased in sarcoidosis patients. Sarcoidosis-lymphoma syndrome has to be considered in patients with previously known sarcoidosis and unexplained recurrence of deep or peripheral lymph nodes enlargement. Any atypical and unexplained symptom mimicking a sarcoidosis flare should encourage the clinician to be careful to differential diagnosis.The granulomatous reactions are not uncommon in the course of solid neoplasia and hematological malignancies. Recent therapeutic advances in cancer treatment, especially the emergence of immunotherapy with ICI, have reminded the possibility of drug induced SLR as it was previously known with older therapies . CS may help control ICI-induced SLR without holding cancer treatments.Differentiating sarcoidosis from cancer-associated granulomatosis is difficult. Atypical presentation of sarcoidosis  may alert the clinician. There is currently no alternative to the histological examination to differentiate sarcoidosis from neoplasia. New radiotracers (18F-FLT) and new acquisition techniques  are promising but currently not available in routine care.A careful and rigorous diagnosis process is required when encountering granulomatosis, on the one hand, because of the increased risk of neoplasia in sarcoidosis patients and, on the other hand, because of the sarcoidosis-like presentation of neoplasia. Discussing with the pathologist in order to sensitize the diagnosis  is fundamental.The sarcoidosis patients are also susceptible to present neoplasia as the general population. Diagnosis can be difficult maybe due to a greater propension to present a granulomatous reaction compared to the general population. Here again, it is essential to share and to discuss clinical presentation to ease the pathologist's work.TE contributed to bibliography, most of writing, and reviewing of the manuscript. PS, YJ, MG-V, and MP contributed to reviewing and writing the manuscript. All authors contributed to the article and approved the submitted version.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.


Phase modulation of light is the core of many optoelectronic applications, such as electro-optic switch, sensors and modulators. Graphene Surface plasmon polaritons (SPPs) exhibit unique properties in phase modulation including dynamic tunability, a small driving voltage and small device size. In this paper, the novel phase modulation capability of graphene SPPs in mid-infrared are confirmed through theory and simulation. The results show that graphene SPPs can realize continuous tuning of the phase shift at multiple wavelengths in mid-infrared, covering the phase range from 0° to 360°. Based on these results, a sandwich waveguide structure of dielectric–graphene–dielectric with a device length of 800 nm is proposed, which shows up to 381° phase modulation range at an operating wavelength of 6.55 µm, given a 1 V driving voltage. In addition, the structure size is much shorter than the wavelength in mid-infrared and can realize sub-wavelength operation. This work paves the way to develop graphene-based tunable devices for mid-infrared wave-front control. Surface plasmon polaritons (SPPs), the electromagnetic waves coupled to charge excitations on the surface of metal, are widely applied in sub-wavelength-scale optical processing . BecauseGraphene, a monolayer of carbon atoms arranged in a honeycomb lattice , has bee3, which have large device sizes and require high external driving voltages [The phase modulation of light is at the core of many applications and much research . Phase mvoltages ,23. Besivoltages . The carvoltages ,25. HoweIn this paper, we explore graphene SPPs phase modulation in mid-infrared by presenting a sandwich waveguide structure of dielectric–graphene–dielectric, which can realize phase modulation from 0° to 360° in situ. The structure length of 800 nm is much shorter than the free-space wavelength in mid-infrared, realizing sub-wavelength operation. Here, we provide a scattering theory for graphene SPPs’ propagating and phase modulation through theoretical derivation and software simulation. The modulation is achieved by controlling the voltage applied to the graphene where the spatial carrier density is tunable. This work constitutes a first step for the application of graphene phase modulation in photoelectric devices such as ultracompact modulators and sensors.Previous structural designs have employed metals directly patterned to graphene as gate electrodes ,27,28. Cx has the advantages of a low charge trap density and high mobility. It can contact graphene perfectly without destroying the carrier mobility of grapheme. As shown in 2) substrate [x isolation layer, monolayer graphene, HfAlOx dielectric layer with a thickness of d, and a 50 nm thick gold electrode. Here, Chemical Vapor Deposition (CVD) is used to grow monolayer grapheme, and then can be transferred to HfAlOx. As revealed in L, which is also the length of the optical path. In this structure, the HfAlOx dielectric layer serves as an effective high-k dielectric for graphene chemical potential tuning when external voltage (gV) is applied between graphene and the metal gate. Here, the 100 nm HfAlOx isolation layer isolates graphene from the environment, which is conducive to maintaining the long-term stability of graphene and preventing the accumulation of substances adsorbed on graphene [HfAlOubstrate , 100 nm graphene ,33,34,35Because SPPs are excited at the appropriate chemical potential, graphene has a strong response to mid-infrared electromagnetic waves . In addiσ is related to the radiation angular frequency ω, chemical potential μ, and relaxation time. The conductivity of monolayer graphene can be obtained from Kubo formula [1τ = 10 fs is the in-band relaxation time of graphene, and 2τ = 1.2 ps is the inter-band relaxation time of graphene. 0 = πe2/2hσ; ħ = 1.055 × 10−34 J·s is the reduced Planck’s constant.Graphene can be considered as a two-dimensional material, and its surface conductivity  formula (1)σintrBy solving simultaneous Equations (1)–(4), the dependence of electrical conductivity on chemical potential of graphene will be obtained. Given a working wavelength 6550 nm, the relationship between graphene electrical conductivity and chemical potential is shown in 0n0 = ε0·εr(v+v0)/(dn·e). fv = 1.1×106 m/s is the Fermi velocity. 0v is the offset voltage caused by natural doping, and its value is 0. 0ε and rε are dielectric constant in free space and relative dielectric constant of the substrate material, respectively. d is the thickness of graphene substrate (the dielectric between gate and graphene), and gV is the voltage applied to graphene.The chemical potential of graphene can be tuned by external applied voltage . The che1k and 2k are P-wave vectors of the SPPs wave in upper and lower dielectric layers, respectively. The relationship between P-wave vectors and the propagation constant of SPPs (β) can be expressed as: m2 = β2-εmk02k, where m = 1, 2. In the proposed structure, 1 = ε2 = εrε (relative dielectric constant of HfAlOx), and we can get the dispersion relation of graphene, as shown in Equation (7) [0k is the propagation constant of electromagnetic waves in air. 0η = 377 ohms is the impedance of free space.Graphene in the proposed sandwich structure can be regarded as a layer of the current. By solving Maxwell equations and the boundary conditions of Maxwell equations, we can obtain the dispersion relation of SPPs wave in TM mode as shown in the following Equation (6) (6)ε1k1+tion (7) (7)β=k0εx medium, it is not necessary to consider the spatial structure of the metal gate. From TM mode wave equation x(y) = Ameiβze-kmy,H it can be seen that different phases ϕ are accumulated after propagation through different path lengths. The phase shifts Δϕ in different optical transmission lengths can be calculated by optical path length L and the real part of β, which can be expressed asSince the attenuation length of SPPs wave is much shorter than the thickness of the HfAlOβ) can be tuned by different voltages applied to graphene and different thicknesses of HfAlOx. Thus, the phase shift of the graphene SPPs wave can be adjusted. The graphene SPPs phase shift is tunable in situ, and can be varied spatially, making it a unique platform for transformation optics in two dimensionsIt can be obtained from the above equations that the propagation constant in transmission direction (gV), HfAlOx dielectric thickness (d), incident wavelength, the dielectric constant of the HfAlOx (rε) and optical path length (L). To further research the influence of all the factors on phase shift, the classical control variable method is adopted here. L is fixed at 800 nm in this structure, which can guarantee a completely adjustable phase shift from 0° to 360° in a voltage range of 5 V. In the simulations, the relative permittivities of Si and SiO2 are 11.9 and 2.09, respectively [Through the discussions in the method section, we can conclude that the graphene SPPs phase shift is affected by a series of factors, including applied voltage  on incident wavelengths for different HfAlOx dielectric thickness  are shown in x used in this simulation is set at 14.3, which is in common use. As revealed in The plots of the simulated phase shift  is shown in To further confirm the theoretical results presented above, the phase modulation performance of the presented structure is simulated and verified using an RF module of COMSOL Multiphysics software. Here, the operating wavelength is 6550 nm with x and SiO2 was carried out to demonstrate the superiority of HfAlOx as a dielectric material. d). It can be observed clearly that HfAlOx has the obvious advantages of a low operating voltage compared with SiO2. Besides this, excellent phase modulation property and perfect contact with graphene make HfAlOx the best choice for dielectric material [In addition, the simulation comparison between HfAlOmaterial .x used in the previous simulations is 14.3. In order to prove that 14.3 is the optimal dielectric constant of HfAlOx under the design parameters of the presented structure, the influence of the dielectric constant of HfAlOx on the phase shift characteristics of the presented structure was discussed here. The value of the dielectric constant of HfAlOx is about between 9 and 20, which is dependent on the manufacturing process and the stoichiometric ratio of Hf, Al and O. Which dielectric constant is the optimal constant depends on other parameters, including applied voltage (gV) and HfAlOx dielectric thickness (d), and the relationship between them is expressed by the formulas shown in the methods. In this simulation, we set the incident wavelength at 6550 nm. As revealed in x, and the dielectric constant of HfAlOx at the maximum phase shift point is different when given different gV and d. This is mainly because the different graphene conductivity resulted from the different gV and d. The maximum of phase shift shows nonlinear changes, which depends on the nonlinear relationship between gV, rε and d. As revealed from x for the presented structure.The dielectric constant of HfAlOx, the dielectric thickness of 100 nm and drive voltage of 1 V, the proposed structure can realize a phase shift of 381° at 6.55 um, where only an 800 nm optical path is needed. The results in this paper confirm the unique properties of graphene SPPs in phase modulation and demonstrate the great potential of graphene SPPs phase modulation in mid-infrared, which can be widely applied to the design of on-chip interferometers and tunable modulators. In this paper, we investigate the phase modulation properties of graphene SPPs in detail. To numerically demonstrate the feasibility of graphene SPPs’ phase modulation, a sandwich waveguide structure of dielectric–graphene–dielectric is presented here. It is found that this structure can realize the continuous tuning of the phase shift in mid-infrared, covering the phase range from 0° to 360°. Given HfAlO


Dλ is not the main factor governing the effective nanoscale screening environment. We observed that the longer Dλ was not the determining characteristic for sensitivity increment and limit of detection (LoD) as demonstrated by different types and ionic strengths of measuring buffers. In the DNA hybridization study, our findings show the role of the additional salts present in PBS, as compared to PB, in increasing graphene electron mobility, electrostatic shielding, intermolecular forces and DNA adsorption kinetics leading to an improved sensitivity.Liquid-gated Graphene Field-Effect Transistors (GFET) are ultrasensitive bio-detection platforms carrying out the graphene’s exceptional intrinsic functionalities. Buffer and dilution factor are prevalent strategies towards the optimum performance of the GFETs. However, beyond the Debye length (λD), the role of the graphene-electrolytes’ ionic species interactions on the DNA behavior at the nanoscale interface is complicated. We studied the characteristics of the GFETs under different ionic strength, pH, and electrolyte type, e.g., phosphate buffer (PB), and phosphate buffer saline (PBS), in an automatic portable built-in system. The electrostatic gating and charge transfer phenomena were inferred from the field-effect measurements of the Dirac point position in single-layer graphene (SLG) transistors transfer curves. Results denote that  Among candidate 2D materials to act as sensing and transducing surfaces in biosensors, graphene is spotlighted for its paramount properties of outstanding electrical conductivity (1738 Siemens/m) [0 W/m/K) , and theuctivity 000 W/m/K0 W/m/K) ,7,8,9. I0 W/m/K) .GS) compared to the back-gated FET that involves the application of a much higher gate voltage [The graphene liquid-gated FET’s attractiveness lies in its simple operation, which applies a drop of buffer acting as a gate onto the modified substrate. The sensing area is generally defined by the patterned source (S) and drain (D), and the system typically requires lower gate potential , which defines the volume where charges are not entirely electrically screened, forming a space-charge layer [D is too solution composition-dependent [D [Electronically, the use of liquid-gated graphene FET is advantageous due to a high transconductance and considerably low noise ,20. Howege layer . The λD ependent ,24, and ndent [D . Althougndent [D ,26, the In this study, we discuss the effects of background electrolyte dilution along with the challenges and trade-off effects on the type of buffer, ionic strength, pH, and the presence of salts, on the limit of detection (LoD), dynamic range, and biomolecular immobilization and binding kinetics in DNA detection. The DNA hybridization detection was performed in a portable and real-time kinetic screening, integrating the multi-array GFET chip with a miniaturized Arduino output reader and an automatic micro-pump. Besides the importance of the ionic strength, we emphasized the significance of using PBS background in DNA detection for the interfacial charge-to-charge interaction on a FET system.2HPO4 and NaH2PO4; PBS tablet, NaCl and MgCl2 for hybridization buffer mixture, 1-Dodecanethiol (DDT) for Au layer passivation, ethanolamine (ETA) blocking agent, and 1-pyrene butyric acid succinimidyl ester (PBSE) for graphene surface linker and other solvents, such as acetone, ethyl acetate, were purchased from Sigma−Aldrich. A MilliQ system provided the deionized water used in the entire experiment (resistivity at 25 °C = 18.2 MΩ cm). Synthetic oligonucleotides representing the specific DNA from the most common grape varieties in Portuguese wines were used in the hybridization study. The 25-mer sequence of the probe DNA (pDNA) with 3′ C7-amino modification (5′- TCA TAA CCG GCG AAA GGC TGA AGC T-3′) and the complementary target DNA (tDNA) sequence of 5′-AGC TTC AGC CTT TCG CCG GTT ATG A-3′) were synthesized by Metabion International AG. Copper foil with high purity (>99.99%) to assist the graphene growth was purchased from Alfa Aesar or Goodfellow.The PB solution components including Na2 and 0.5 mm height is used to conduct a dynamic flow onto the sensor’s surface. The inlet dimension is 0.5 × 0.5 × 9 mm3, while the outlet is 0.5 × 0.5 × 6 mm3.Confocal Raman spectroscopy using a WITec Alpha300 R instrument equipped with a Zeiss microscope set of lenses is performed to characterize the graphene channel before using the entire study’s GFET chip. The determination of the Dirac point through the graphene transfer curve is obtained by plugging-in the GFET chip into the built-in credit-card-size Arduino board consisting of a microcontroller, 16-bit digital to analog converters (DAC), 8-bit digital potentiometer, and resistance-controlled current source of 1–100 µA and complementary metal-oxide-semiconductor (CMOS) matrices. The setup is connected to a desktop computer to monitor sensor arrays’ output signal up to twenty transistors. An automatic micropump of a microfluidic system is incorporated for the biomolecular binding kinetic study of the DNA in different electrolytes. A PDMS chamber fitting the layout of the chip with 7 mm2. A 5 nm Cr was used as an adhesion layer for 40 nm Au deposition. The source (S), drain (D), and gate (G) were patterned using photolithography. A multi-layer of SiO2 and 250 nm Si3N4 was patterned with reactive ion etching (RIE) for current lines passivation. The process was then continued with the single-layer graphene transfer described elsewhere [2 graphene channel, and the gate diameter was 2.8 mm. The layout of the chip is depicted in GFET chip is fabricated on a 200 mm Si wafer  covered with 200 nm SiOlsewhere  onto theGFET surface characterization is done by Raman spectroscopy to assess the graphene channel quality. The measurement is performed at room temperature in a backscattering geometry with 532 nm and 633 nm lasers excitation using a confocal Raman microscope at an output power of 1.5 mW and an objective ×50 lens, with a numerical aperture of 0.7. A 600 groove/mm grating for three acquisitions under 10 s acquisition time is set to collect the Raman spectra at different random points of the graphene channel to assure the graphene’s uniformity as also checked by Raman imaging.The performance of solution-gated graphene FETs can be affected by the content and the electrolyte solutions’ concentration. We performed the following experiments to study ionic strength’s effect on the solution-gated graphene FETs’ performance. The GFET chips were washed with acetone for photoresist removal, soaked in ethyl acetate for 2 h for a better cleaning step, and, for electronic reading in a portable device, wire-bonded onto a printed circuit board (PCB). Transfer curves (TCs) were collected using PB of different concentrations . On the other hand, to study the effect of pH on the performance of solution-gated graphene FETs, TCs were collected on a 10 mM PB buffer, and pH ranging from pH 5.0 to pH 9.0, where the pH is adjusted for each solution by adding small amounts of sodium hydroxide (NaOH) or hydrochloric acid (HCl).2 flow. The PBSE contains two binding sites; pyrene groups that attach to graphene through π−π interaction, and an ester group on the other side to capture the amine-tagged pDNA through NHS reaction. After modifying PBSE, a 10 µL of 10 µM pDNA is immobilized onto the PBSE modified graphene and kept in a humid chamber for 16 h at room temperature. To minimize the non-specific binding, a 10 µL of 10 mM ETA is added and stood for 30 min. A 10 µL of complementary tDNA is incubated for 1 h for the last stage’s hybridization process. The surface modification stages are illustrated in DS) under constant drain-source voltage (VDS) as a function of gate-source voltage (VGS).To optimize the DNA immobilization area on the graphene channel, the Au receded gate is passivated with 2 mM DDT in ethanol for 16 h a. Next, The GFET sensor chip and a PDMS flow cell fitting the sensor layout are assembled and inserted in the portable platform a. This s2 precisely flanked by two identical square Au source and drain large contacts covered with graphene, defining the channel length and providing an ohmic contact to the channel. In this way, efficient charge injection and collection from the channel are achieved in the biomolecular screening area even at low source-drain voltage.As displayed on the sensor’s layout in −1 [2 substrate exhibits the features of pristine monolayer graphene with negligible D peak at ~1351 cm−1, as well as a 2D (~2696 cm−1)-to-G (~1588 cm−1) intensity ratio (I2D/IG) of ~1.78. Subsequently, the Au surface blocking with DDT to eliminate the binding sites for the DNA/Au interaction was shown to have no impact on the monolayer graphene structure indicated by the spectral and intensity coincidence of the fingerprint peaks with those of the intact graphene. After PBSE functionalization, the I2D/IG dropped to ~1.11, which is indicative of the disorder on the graphene surface concomitantly producing defects, as seen by the appearance of the D peak (~1351 cm−1). The D’ peak at ~1624 cm−1 emerging as a G peak shoulder is related to the graphene’s surface’s impurities and charges. This behavior is similar to that reported by Tsang et al., 2019, who chemically modified a graphene sensor for exosome identification [2D/IG ratio of dominant value of ~1.8–2.5 with a scanning area of ~2.3 mm2  trapped at the graphene/substrate interface that act as scattering centers for the conduction electrons. At concentrations below 1 mM, PB could not provide adequate gate capacitance or trapped charge passivation for a high-mobility channel to form.The modulation of the channel conductance by the applied gate voltage is mediated by the capacitance of the interface graphene/liquid electrolyte, which depends on the solution’s ionic strength. But the ions and polar molecules that accumulate at the interface also have the effect of neutralizing any charges trapped at the graphene/silicon oxide substrate. DS-VGS curves towards lower gate voltages. This observation agrees well with previously reported work [DLC) formed at the graphene-electrolyte and electrolyte-gate interfaces. Since the Debye length (Dλ) which sets the thickness of the EDLs, is proportional to the square-root of the inverse ionic strength of the solution (see Equation (1) and reference [Dλ and larger EDL capacitance, requiring less GSV to accumulate a given amount of charge in the channel. The Dirac point shift presented in Another effect observable in ted work  and is eeference  herein),− groups, generating n-type doping of graphene, raising the electrons’ chemical potential in graphene. Therefore, with the more electron-donating species (high pH), the TCs shift to lower GSV. We also believe that defective sites in graphene could assist in the chemisorption of the OH− ions present in high concentration when the pH is above neutral, leading to charge tunneling onto the graphene and adding up to the charge transfer efficiency. The linear relation between Dirac point position and pH is depicted in In interfacial sensing with GFETs, the conductance is mainly influenced by two concurrent mechanisms: Local gating by charged molecules in the vicinity of graphene that perturb the EDL and locally change the gate capacitance, and electron transfer, which may oppose the former effect, giving rise to opposite Dirac point shift directions . In our Dλ for molecular binding events to occur inside the sensing interfacial volume [Dλ = ~21 nm). In effect, comparing Dλ with the size of the DNA molecule attached to the binder (DNA + PBSEl = ~10 nm), one sees that for high ionic strengths, the DNA duplex, which is more rigid than the single-stranded, becomes longer than the EDL , thus decreasing the sensitivity because some hybridization part occurs outside the EDL area.The selection of the liquid gate electrolyte plays an essential role in the overall performance of the GFET device, as discussed in the previous section. In a GFET biosensor, the electrolyte is typically a solution where the bio-compounds are maintained and is composed of buffer and salt species to keep the pH stable upon the presence of charged molecules in the solution. The counter ions in buffers influence the sensing mechanism in two ways: The adjustment of l volume  and the DLC by the negatively charged DNA molecules that induce an equal amount of positive charge in the graphene channel, further lowering the electron chemical potential (Fermi level). Therefore a larger VGS is required to raise the Fermi level into the conduction band, which occurs precisely at the Dirac point, as observed experimentally and is shown in In DNA detection with the GFET, the Dirac point shifts to progressively higher voltages upon increasing the concentration of tDNA to hybridize the pDNA. Similar trends are observed in the detection using PBS buffer with 0.01×, 0.1×, and 1× dilutions, as seen in mg for both the TC’s electron and hole branches. This fact emphasizes the salts’ effectivity in contributing to shielding charged impurities trapped in the SiO2 substrate and on the graphene surface [The transfer curves acquired after each surface functionalization step reveal a common Dirac point shift direction, measured in both PB and PBS, after DDT (Au blocking), PBSE (linker attachment), ssDNA (probe immobilization), and ethanolamine (blocking), respectively . Using a surface ,31. On t surface ,33. In D surface . The comD, LoD, linearity, and sensitivity, are presented in D of ~2.1 nm) provides the lowest sensitivity (9.22 mV/decade). In comparison, the highest sensitivity (16.47 mV/decade) is obtained in 0.1 mM PB (λD of ~21 nm). An extended dynamic range, one extra order of magnitude of concentration in the linear detection range of tDNA (10−18–10−15 M) than found in the detection with 10 mM PB (10−18–10−14 M), is also observed. Similar trends are found in the DNA hybridization detection with PBS. The lowest ionic strength (0.01× PBS) resulted in the highest sensitivity (26.69 mV/decade), which can be explained by the increase of Debye length. Nevertheless, in a comprehensive comparison of PB and PBS buffers, the Debye length is not the sole factor impacting the sensitivity. The measurement in 0.01× PBS (λD of ~7.6 nm) achieves ~62% higher sensitivity than that in 0.1 mM PB with higher Debye length (λD = ~21 nm).The calibration plots displayed in q + 1/CDL + 1/CDiff where Cq is graphene quantum capacitance [DL is the electrical double-layer capacitance, and CDiff is the capacitance at the diffusion layer [CT) in the Stern layer typically connected in parallel to the CDL [DL resulting from the accumulation of small-sized counterions penetrating in between the DNA strands, while the opposite occurs in DNA detection with the PB background. The trade-off effects of the Debye length over sensitivity are modeled in DL with a faster potential rise resulting in a shorter Debye length than that occurring in measurement with PB.The interfacial ionic density caused by additional salts’ presence in DNA detection is schematically depicted in acitance , CDL is on layer . It is s the CDL ,38. HoweD) is fundamentally linked to ionic strength, pH, and variation in the double-layer capacitance (CDL). Phosphate buffer (PB), made up of various ratio (R) of monobasic  has been widely used in various biomolecular detections such as proteins, lipids, oligonucleotides, and many more since its additional salts of NaCl and KCl may provide much improved in-vivo mimicking condition of an in-vitro ambiance. The concentration of the phosphate ions in PB can be predicted through the dissociation equilibrium below:The quantification of the limit of detection (LoD) of the DNA hybridization detection onto the GFET sensor under PB and PBS background is explained using the empirical model from the modified Hill’s function for the dose-response data. In the electrolyte gated FET configuration, the Debye length  is calculated as follows:The ionic strength λD= εFor the statistical analysis for the DNA hybridization study, all the standard deviations in the calibration plots were taken from triplicate measurement on three individual sensors belonging to the same chip under identical experimental condition. The modified Hill’s function from Origin 9 software  was applied to perform the non-linear regression of the recorded dose-response data with the fitting equation below: To estimate the limit of detection (LoD) of the GFET sensor, we calculated two initial parameters  to be neThe modified Hill’s function has been reported to fit well the correlation of the biosensor’s response to the binding activity . We founIn various DNA adsorption setups onto a sensor, the association constant significantly depends on the salts’ concentration . To compy refers to the dependent parameter, the Dirac point voltage, which is equivalent to fractional coverage (θ), typically used in the Langmuir adsorption isotherm realm. The x refers to the incubation time, and b is equal to the equilibrium constant K (d/kak) [ak and dk are the rate constants for adsorption and desorption, respectively. In this experiment, we focused on the immobilization of the probe DNA molecule; hence, the dk is considered the same value in both background electrolytes. With a constant number for dk, it is estimated that based on the obtained fitting variables, the pDNA adsorption, ak, in PBS background is greater than that in the PB , indicating faster isotherm properties.In this equation,  (kd/ka) ,44, wherDirac under PBS screening. This finding aligns well with the ionic gradient’s impact, penetration, and the electric potential explained in A series of interfacial ionic interactions on liquid-gated GFET sensors, operated in a miniaturized and portable DNA screening system, is described in detail using different background electrolytes’ employment. The ionic strength adjustment was the most critical stage in applying the GFET sensor. The single-layer graphene structure in a FET channel is sensible to pH change, due to a charge transfer mechanism. A distinct behavior of PB and PBS, the prevalently used background buffers in bio-detection, along with the impact of the dilution, was recorded. Carried out in DNA hybridization detection, both PB and PBS demonstrated the dilution’s effectivity in improving sensitivity and dynamic range. However, a significant finding is that Debye length is not the sole factor in the GFET device performance. Despite the longer estimated Debye length achieved in PB background, the sensitivity is not higher than in PBS background. The additional salts in PBS increase graphene carrier mobility due to more efficient charge impurity passivation by counterions at the interface than in PB. These crowding ions may penetrate more in-depth to the Stern layer at the sensor’s surface, significantly affecting the total surface potentials and reinforcing the DNA charges’ electrostatic shielding. The additional salts in PBS also accelerated the isotherm kinetics of the oligonucleotides adsorption onto the surface. The choice for a precise optimum buffer concentration is indeed different for different molecular targets due to the biomolecules’ intrinsic chemical functions. Here, some guidelines for the selection of the most suitable buffers were established.


Graphene-enhanced Raman scattering (GERS) on isotopically labelled bilayer and a single layer of pristine and partially hydrogenated graphene has been studied. The hydrogenated graphene sample showed a change in relative intensities of Raman bands of Rhodamine 6 G (R6G) with different vibrational energies deposited on a single layer and bilayer graphene. The change corresponds qualitatively to different doping of graphene in both areas. Pristine graphene sample exhibited no difference in doping nor relative intensities of R6G Raman peaks in the single layer and bilayer areas. Therefore, it was concluded that strain and strain inhomogeneities do not affect the GERS. Because of analyzing relative intensities of selected peaks of the R6G probe molecules, it is possible to obtain these results without determining the enhancement factor and without assuming homogeneous coverage of the molecules. Furthermore, we tested the approach on copper phtalocyanine molecules. One of the restrictions of this approach is the limited stability of the metals that are needed to achieve signal enhancement3. Recently, it was observed that graphene itself can provide significant enhancement of the Raman signal and the so-called graphene-enhanced Raman scattering (GERS)6 was established. Note that both SERS and GERS can contribute to the molecular Raman signal together7. Apart from the relatively good chemical stability of graphene, it was also found that graphene quenches photoluminescence8, which is important for practical experiments. The GERS was observed for various molecules11 and also for other 2D materials, which were employed as active substrate12. Furthermore, it was shown that the enhancement can be tuned by changing the Fermi energy of graphene 13, by substitutional doping with heteroatoms15, or by chemical functionalization17. More detailed studies demonstrated that the enhancement is also a function of the phonon energy of the specific vibration and also laser excitation energy10. The observed effects were rationalized by a simple theoretical approach taking into account several different resonance processes18.Enhancement of the signal in spectroscopy has crucial importance for detection and study of a low amount of species. For Raman spectroscopy, the surface-enhanced Raman scattering (SERS) technique is widely used16. The overall GERS enhancement depends on the laser excitation energy, lowest unoccupied molecular orbital (LUMO), and highest occupied molecular orbital (HOMO) energies of the probe molecules, the vibrational energy of the actual molecular Raman mode, and on the Fermi energy of graphene18. Specifically:EL and EH are the energies of the molecular LUMO and HOMO states, respectively, and EF is the Fermi energy of graphene.It was already shown previously that different doping of graphene induced by functionalization leads to a change in the relative intensities of individual GERS peaks of the probe molecules16.For a given vibrational energy of a given molecule, measured in resonance with a given laser, the enhancement depends only on the doping level of graphene. Because of the huge photoluminescence signal of R6G molecules that are not placed on graphene, it is not possible to measure Raman spectra and therefore it is impossible to calculate the enhancement factor. However, as shown previously, even without knowledge of the enhancement factor, the effect of different doping of graphene can be rationalized by comparing relative intensities of individual GERS peaks20. The effects of the substrate may include doping21, strain22, and/or mixing of electronic states23. The easiest approach to study the effect of the substrate is a comparison of the behavior of single-layer graphene and turbostratic graphene bilayer on SiO2/Si substrate24. Hence, one can compare graphene on Si/SiO2 vs graphene on graphene. To differentiate between the top and bottom layers of the graphene bilayer in the Raman spectra, one can employ isotopic labelling of the graphene layers: one graphene layer is prepared using natural methane gas while the other by 13C-enriched gas. The different atomic masses of 13C and 12C result in different Raman shifts of the Raman modes and therefore 12C and 13C graphene layer can be easily distinguished25.It was shown that the substrate significantly affects the graphene layer26, sensors based on graphene field-effect transistors28 or resistivity changes30 have been widely studied. However, the main drawback of graphene sensors is their low or zero selectivity. This can be improved by the modification of graphene32. Another approach is to involve multiple detection techniques. Hydrogenated graphene has been suggested recently as a platform for electrochemical sensing33. Therefore, combining electrochemical sensing with GERS could extend the possibilities of hydrogenated graphene for sensor applications. Therefore, understanding the GERS effect employing hydrogenated graphene is required. Furthermore, hydrogen in hydrogenated graphene can be replaced by other functional species34, opening a large area of possible functionalized graphene substrates for GERS that could achieve higher enhancement for specific molecules.Graphene as a monatomic layer has a potential for application in ultrasensitive sensor devices. Apart from photonic sensors employing the enhanced Raman signal2 substrates. We employed atomic force microscopy (AFM) and Raman spectroscopy to address the properties of the graphene, which enables us to correlate changes in graphene status with the changes of the GERS. Thanks to comparing the relative intensities of the Raman bands of R6G we were able to explain our results by theoretical predictions18 without determining the absolute enhancements factors and the density of the R6G molecules on individual substrates. Copper phtalocyanine molecules (CuPc) were tested on the SLG/BLG system as well.In this work, we compare the GERS effect on pristine and hydrogenated graphene using a probe molecule, R6G. We also addressed the effect of the substrate by evaluation of the GERS on hydrogenated graphene on graphene and SiO13C graphene layer partially covers Si/SiO2 substrate and 12C graphene layer is placed on top of that structure and finally, the R6G molecules are deposited. The region where the pristine 12C graphene layer is placed on the 13C graphene layer is labelled as R6G/P-BLG. The region where the pristine 12C graphene layer is placed directly on the Si/SiO2 substrate is labelled as R6G/P-SLG. In the second case, the graphene sample was hydrogenated before the deposition of R6G molecules and hydrogenated graphene bilayer region is labelled as R6G/H-BLG while hydrogenated single layer region is labelled as R6G/H-SLG.The layout of the samples is shown in Fig. 12C CVD graphene transferred over 13C CVD graphene. For the purpose of the measurement, we intentionally chose a spot with a crack in the bottom 13C graphene layer. Thus, we could study the samples with 13C/12C bilayer graphene  and 12C single-layer graphene  at the same time.The GERS is sensitive to the status of graphene, therefore, it is necessary to characterize graphene properties in detail. Both pristine and hydrogenated graphene samples consisted of 35. In the Raman signal from the isotopically labelled bilayer, the peaks coming from 13C graphene are shifted with respect to 12C graphene peaks . The more the peaks are separated, the bigger is the difference in their enhancement. This effect is schematically shown in Fig. 18. We assumed the Fermi energy of the intrinsic graphene layer to be at −4.6 eV and the LUMO and HOMO energies of the R6G molecules to be at −3.4 eV and −5.7 eV, respectively8. The data points shown in Fig. −1 and 1650 cm−1 on R6G/H-SLG. The light green squares, corresponding to R6G/H-BLG, are plotted for lower Fermi energy of graphene because the bottom layer of hydrogenated graphene showed higher doping level than the top one. From Fig. −1 related to the intensity of the R6G band at 610 cm−1 will be higher for more doped graphene.Because the GERS enhancement depends on the actual vibrational energyet al.40. When applying strain, the Raman shift of the 2D peak versus G peak is moving along the iso-doping line  from the point of neutral and unstrained graphene, while when applying doping, the shift is along the iso-strain line (slope of 0.742). The G peak upsifts for both n and p-doping43. In real samples, both effects are present and thanks to the known values of both iso-doping and iso-strain slopes, one can decouple the contribution of strain and doping. In case of an isotopically labelled bilayer prepared by sequential transfer, the individual layers do not electronically interact, which is demonstrated by unaffected shape of the 2D band44. Thus, doping and strain of individual layer can be analysed independently45. Effect of strain and doping on Raman spectra of interacting multilayer has been investigated previously for example by Jeon et al.46 In the case of pristine graphene sample  of Fig. 12C 2D graphene mode of pristine and hydrogenated graphene, respectively. In the case of both samples, the 2D FWHM is higher when the graphene layer is directly on the Si/SiO2 substrate than on the other (13C) graphene layer. The increased width of the 2D mode indicates sub-micron strain inhomogeneities47. The higher 2D width of graphene on Si/SiO2 substrate compared with the upper layer of isotopically labelled graphene bilayer is consistent with our AFM results, showing a higher relaxation of the top layer of BLG compared to SLG sample, which is consistent with previously published measurements49.In Fig. 48 and showed in Fig. 12C graphene layer is placed on 13C graphene layer than when directly placed on Si/SiO2 substrate. Graphene placed on another graphene layer is more likely to release strain, which is consistent with previously published data49. Since the size of the crack is larger than 10 μm, any effect on strain at the edges are expected to be negligible. Doping of the 12C graphene layer is higher for the R6G/H-SLG sample than with the R6G/H-BLG sample. This behaviour is consistent with published data as well50. However, in the case of pristine graphene, no significant change of doping is observed between R6G/P-SLG and R6G/P-BLG. Note that the p-doping is generally higher for pristine graphene, which is in agreement with previous findings. It was reported that partial hydrogenation induces n-doping in graphene51.Figure −1 (A610) relative to the intensity of the R6G peak at 1650 cm−1 (A1650) for pristine (a) and hydrogenated (b) graphene samples. One can immediately notice that while in the case of the pristine sample, the ratio (A610/A1650) is constant within the map, in the case of the hydrogenated sample the ratio (A610/A1650) is significantly lower in the R6G/H-SLG region.In Fig. −1 with respect to the R6G mode at 1650 cm−1. In the case of the hydrogenated graphene, one can apply a similar approach: (i) R6G Raman peaks with higher vibrational energy are more influenced by the GERS enhancement than the peaks with lower vibrational energy, (ii) more p-doped graphene layer will provide higher enhancement for the R6G Raman peaks. Therefore, higher doping of graphene provides higher sensitivity of the enhancement of the R6G Raman signal with respect to the vibrational energy of the particular Raman mode. In other words, with higher p-doping of graphene, the difference in enhancement between low-energy vibrational mode and high-energy vibrational mode will be higher than with less p-doped graphene. This is exactly what we observe in Figs. As shown in Fig. The observation that the ratio of the intensities of the R6G Raman peaks does not change for R6G/P-SLG and R6G/P-BLG areas provides us more information. This demonstrates that only doping of graphene and not a strain plays a role in GERS enhancement. For example, a single-layer graphene has a larger strain and broader 2D band Fig. . None of610/A1650 ratios is plotted in Fig. 610/A1650 ratio is decreasing. It is worth noticing that for higher p-doping the change of the A610/A1650 ratio is faster. This is again in very good qualitative agreement with the scheme in Fig. −1 and peaks at 780, 1180, 1360, and 1650 cm−1, respectively, on SLG region with respect to the BLG region  and bilayer graphene (R6G/P-BLG) and consequently, it also did not show any difference in the ratio of the R6G peaks. Because of the constant ratio of the R6G peaks, we can exclude the effect of strain and strain inhomogeneity on the GERS effect because the strain differed from single layer to bilayer graphene. The relative intensities of the R6G peaks are in agreement with the doping variations of graphene even when comparing pristine and hydrogenated graphene. Analysis of the relative intensities of all accessible R6G bands on SLG and BLG region of pristine and hydrogenated graphene confirmed the theoretical concept as well. Furthermore, we also probed CuPc molecule (SI). The change of relative intensities of CuPc Raman modes agrees with the theoretical expectations and the results with R6G, however, it is not so pronounced. Therefore we analyzed relative intensities of several peaks with respect to SLG and BLG part which confirmed the observed trend.In this work, we studied the GERS enhancement of the R6G molecules deposited on isotopically labeled graphene bilayer and single-layer graphene to address the effects of hydrogenation and substrate. In the case of the hydrogenated graphene sample, the different doping of the single-layer (R6G/H-SLG) and bilayer graphene (R6G/H-BLG) induced different enhancements of individual R6G Raman peaks. This difference was described as a ratio of the intensities of the R6G Raman peak at 610 cm52. Isotopically labelled graphene layer was prepared using 13CH4 as a precursor19. 13C graphene was transferred onto the Si substrate with a 300 nm thick SiO2 layer (Si/SiO2) using the nitrocellulose-assisted method53. Isotopically labelled graphene bilayer was prepared by subsequent transfer of 12C graphene using the same method. Isotopic labelling was used to be able to study individual layers independently using Raman spectroscopy. One of the samples was hydrogenated in a high-pressure autoclave as described elsewhere34. Briefly, the autoclave was flushed several times with hydrogen to remove air. Then, the autoclave was filled with hydrogen at a pressure of 5 bar. The temperature was increased from room temperature to 200 °C. The reaction was carried out for 2 hours at roughly 8 bar.Graphene was prepared by a chemical vapor deposition (CVD) method on copper foil−6 mol·l−1 aqueous solution for 2 minutes. The substrates were subsequently immersed in deionized water for 30 minutes to remove possible excess of the R6G molecules.The R6G molecules  were deposited onto graphene by soaking the substrate in a 10The Raman maps were measured with a Witec alpha300 R spectrometer equipped with a piezo stage. The excitation laser wavelengths of 532 nm and 633 nm with the laser power below 1 mW were used. The laser was focused on the sample with a 100× objective to a spot with a diameter of around 500 nm. All the Raman peaks were fitted using pseudo-Voigt functions.Supplementary Information.


Tribological properties of glass fiber-reinforced polymer (GFRP) composites used in reciprocating contact should be improved to secure the efficiency and safety because of risks of abrasion, adhesion, and fatigue deficiency amidst fiber, matrix, or interphase. This paper investigates the influence of graphene reinforcement on the wear resistance of a GFRP composite. Graphene was integrated into a typical GFRP composite as the surface coating using a modified resin film infusion method with the percolating paper assisted. Dry reciprocating sliding tests were performed against a stainless steel ball moving in a direction 45 degrees to the fiber orientation. The morphology of the worn surface was observed, and the corresponding wear mechanisms are discussed. Results suggest that the prepared graphene coating improves the wear resistance of the GFRP composite. The protected GFRP laminates remained intact during the first 20 min of the wear test and only a small fraction of fibers were broken after 60 min test. Furthermore, abrasive debris and fiber breaks originating from composite were markedly reduced, likely owing to the formation of a protective transfer film between the surface of the modified composite and the rubbing counterpart. Nowadays, GFRP composites are widely used in a variety of engineering applications, such as pipes in the petroleum and mining industries, helicopter rotor blades, pump impeller blades, high-speed vehicles, and aircraft parts ,2. Altho2O3) , silicon2O3) , and nan2O3) [2) ) can be 2O3) [2) . −3 mm3/Nm to 10−7 mm3 after incorporating graphene, which improved the fracture toughness and fatigue performance [Among the available fillers and reinforcements, graphene can endow composites with excellent self-lubricating properties by forming graphitic structures on the surface of the material . In addiformance . Graphenformance .Based on the discussion above, graphene has been shown to improve antifriction and antiwear performance synchronously. However, further improvements of wear performance by combining both the lubricating and reinforcing effects of graphene have not been evaluated. Furthermore, processability of composite structures remains an important issue to address. For instance, buckypaper and other films are not large enough to cover the surface of large-scale composite structures, such as turbine blades or the skin of an aircraft, mainly owing to the limitations of current manufacturing techniques . Also, tTo overcome these issues, this paper investigated the influence of graphene reinforcement on the wear resistance of a GFRP composite. Different forms of graphene (a coating preparation and embedded in interlayers) were compared in terms of their antiwear performance. To realize the designed structure, a modified percolating-assisted resin film infusion method was used to add an equivalent amount of graphene to preformed glass fiber-reinforced laminate. Finally, the results of dry reciprocating sliding tests were used to compare the effectiveness of each preparation.2, CW200XP, Taishan Fiberglass Inc. Taishan, China). All vacuum bagging materials were supplied by Sino-composite Co. Ltd. The epoxy matrix system used in this study was comprised of bisphenol A epoxy resin , phenolic epoxy resin , and polyethersulfone . The 4,4′-diamino-diphenylsulfone  was used as the curing agent. Large-diameter graphene with a length of 7–12 μm and 1–3 layers was obtained from Guosen Shenzhen company. The graphene was produced using a mechanical exfoliation method to maintain its stiffness and strength . BidirecThe multi-scale reinforced laminate was fabricated using percolating-assisted resin film infusion, according to a previously described protocol . Briefly2), the observations of the worn surface were focused on the middle section of the whole abrasion area that contained the deepest point in the worn surface, in order to give a representative damage of the worn morphology.The prepared coating samples were observed by digital optical camera  and scanning electron microscopy . The cross-sections of samples were prepared by grinding and polishing before the observation. Reciprocating sliding tests were performed to investigate the wear performance and the coefficient of friction (COF) of the composite. Prepared samples were tested on a multifunction wear tester  and a stainless steel ball  with a hardened and smoothly polished surface served as the counterpart. All samples were degreased and cleaned using acetone and ethanol before testing. Reciprocating tests were carried out at 23 °C in ambient air and testing cycles were implemented for 20 min and 60 min. A normal load of 30 N (Newton) was applied to the sample at a speed of 300 rpm and the total moving distance was 5 mm. To accelerate the wear behavior and obtain a relatively even surface morphology, prepared samples were fixed using a jig with an angle of 45° between bidirectional fibers and the sliding direction . The weaIdentical amounts of graphene (0.4 g) were introduced into GFRP laminates by either interlayer embedment or coating preparation. Surface morphology of prepared samples are shown in Enlarged images of the prepared samples (N-0.4 g and I-0.4 g) are presented in In Worn surface after the first 20 min of the friction test were presented a–c. The In contrast, the raw GFRP and the interlayer embedment samples exhibited a bumpy, worn surface. The worn surface profiles at the deepest point  characterization of the center of the worn surface can further explain the friction behavior . The worTo further study the antiwear resistance of the integrated surface coating, a typical buckypaper of graphene was selected as a surface coating and a comparative analysis was performed. The buckypaper coating containing an equivalent amount of graphene (0.4 g) was prepared using a previously described protocol , and co-Since the lowest depth of the worn surface (300 μm) exceeded the thickness of the surface coating b, it canFrom the discussion above, it is essential to supply a supportive transfer film between the composite and the counterpart to promote relative sliding friction and, thus, reduce wear. The protective effect was further examined by decreasing the thickness of the applied coating. After the 20-min reciprocating sliding test, the worn surface of C-0.05 g exhibited a blurred morphology indicating that a large quantity of fibers broke due to plowing and scuffing from the counterpart a. In conThe worn depth of the coating sample increased with thickness of the coating preparation. However, the real worn depth of the protected composite (after subtracting the coating thickness) exhibited the opposite trend e,f. In tWhen the test time was increased to 60 min, the C-0.4 g sample still maintained a smooth, worn surface, except for a small area of scratches a. The woDetails of the worn surface of the coating sample are presented in A lateral view of the worn integrated coating shows that fractures exhibited a flaky shape c,d, contIn The COF of the interlayer embedment sample followed a similar pattern b, but stThe buckypaper coating produced a COF curve similar to that of raw GFRP and interlayer embedment c. The seCompared to the buckypaper coating, the graphene coating in this paper led to continuous growth of the COF, which gradually increased up to 0.9 d, indicaThe results of this investigation demonstrate a feasible approach for improving the wear resistance of GFRP. Graphene was accumulated on the GFRP surface via filtration mechanisms using a modified percolating-assisted resin film infusion method. The obtained graphene coating exhibited superior antiwear resistance compared to interlayer embedment and the buckypaper coating. As the graphene content was increased in the coating preparation, the protective properties improved. The proposed coating sustained loading of 0.4 g while completely protecting the inner composite during the first 20-min sliding abrasion test, and continued to be protective for the following 40-min test. By analyzing the morphology of the worn surface and the tribological process, the wear mechanisms were revealed. Compared with other samples, the coating preparation can simultaneously provide a durable transfer film while promoting the pinning effect. Micrographs of the worn surface show that the layer of assembled graphene in the graphene coating was compacted by the counterpart to form a dense transfer film, which improved the wear behavior of the composite by preventing direct contact between surfaces of the composite and the rubbing counterpart.