P < 0.001). We concluded that IPF increases LC risk, and LC weakens survival outcomes in IPF. Close surveillance for LC development is mandatory for patients with IPF.Idiopathic pulmonary fibrosis (IPF) is an independent risk factor for lung cancer (LC) development; however, there are currently no clinical guidelines for LC surveillance in IPF. This study aimed to investigate the cumulative incidence and survival outcomes of LC in IPF. Using the National Health Insurance Service database, including medical information on people aged ≥ 40 years between 2011 and 2016, we identified IPF patients and confirmed the presence of comorbid LC. Patients diagnosed with IPF in 2011 were washed out, and mortality data were analyzed from 2012 to 2018. A total of 7277 newly diagnosed IPF patients were identified among Korean citizens aged ≥ 40 years (about 50 million people) between 2011 and 2016. Their average age was 71.5 years and 72.8% of them were male. The prevalence of LC in the IPF cases was 6.4%. The cumulative incidence rates of LC in IPF patients who did not have LC at the time of IPF diagnosis were 1.7%, 4.7%, and 7.0%, at 1, 3, and 5 years, respectively. The median time from IPF diagnosis to LC development was 16.3  months. The survival rate was significantly lower in the IPF with LC group than the IPF without LC group ( Epidemiological studies have revealed that IPF is an independent risk factor for lung cancer (LC) development after adjusting for shared risk factors. Hubbard et al. reported that the relative risk of developing LC in IPF is approximately eight times higher than in the general population, after adjusting for smoking history, based on United Kingdom healthcare databases3. The prevalence of LC in IPF was reported to be 4.4–13%, and up to 48.2% in an autopsy study of 83 usual interstitial pneumonia patients9. LC in IPF occurs more frequently in older male smokers and patients with combined emphysema10. Comorbid LC significantly affects survival in IPF. The mortality values are higher among IPF patients with LC than IPF patients without it13 and those with LC in the general population14. Additionally, the treatment of LC itself can cause acute IPF exacerbation, which is the most lethal life-threatening complication of IPF17.Idiopathic pulmonary fibrosis (IPF) is the most commonly occurring type of idiopathic interstitial pneumonia, characterized by chronic, progressive, fibrotic interstitial lung disease of an unknown cause and a histopathological pattern of usual interstitial pneumonia18. In the absence of an official recommendation for LC screening in IPF, a large number of IPF patients are diagnosed with advanced LC at the time of hospital visit due to symptom development over several years.Despite the presence of notable epidemiologic associations between LC and IPF, and poor survival outcomes, there are currently no clinical guidelines for the screening of LC in IPF; since the natural history of IPF is highly variable, some patients show a relatively stable disease course without symptoms and, therefore, do not routinely visit hospitalsIn this study, we investigated the demographic characteristics, cumulative incidence, and mortality associated with LC in IPF patients using nationwide data to suggest the direction of LC surveillance.P < 0.001) and average age was higher  in the IPF without LC group than in the IPF with LC group. Similar proportions of urban and rural area-dwelling patients were observed in both the IPF without LC and IPF with LC groups. More than 40% of the patients in both groups were included in the fifth quintile of household income, the lowest socioeconomic status, and the distributions of household income were similar between the groups. Of the 464 patients in the IPF with LC group, 254 (54.7%) were diagnosed with IPF before LC, 127 (27.4%) had a simultaneous diagnosis of IPF and LC, and 83 (17.9%) were diagnosed with LC before IPF. Patients were classified as having a “simultaneous diagnosis” if LC was diagnosed within 3 months of IPF being diagnosed. Patients diagnosed with IPF more than three months in advance of the LC diagnosis were classified into the “IPF in advance” group, while those who were diagnosed with LC more than three months in advance of IPF were classified into the “LC in advance” group. The baseline demographics of the IPF with LC group, according to the order of diagnosis, are shown in Supplementary Table A total of 7277 newly diagnosed IPF patients were identified between 2012 and 2016. Their average age was 71.5 years and 72.8% of the study population was male. Of the IPF patients, 464 (6.4%) were diagnosed with LC during the study period. The baseline demographics of the IPF patients with and without LC (IPF with LC and IPF without LC groups) were compared  and age at the diagnosis of IPF  were independent risk factors for mortality in IPF patients  months, and 81.8% of the IPF patients with LC developed LC in 3 years from IPF diagnosis8. However, each of the three aforementioned studies was conducted at a single center. Yoon et al. conducted a study based on interstitial lung disease registry data in the United States, which included 1108 IPF patients, and reported that the median time from IPF diagnosis to LC development was 53.0  months, and the incidence of LC increased in the first two years after IPF diagnosis, which persisted until year four13. The present study is the largest nationwide cohort study to date based on the NIHS database of almost all South Korean citizens aged ≥ 40 years (about 50 million people) and included 7277 IPF patients from this population. In this study, the cumulative incidence rates of LC in IPF at 1, 3, and 5 years of 1.7%, 4.7%, and 7.0%, respectively, were lower than those observed in previous studies. IPF shows a varied natural course after diagnosis18; therefore, patients who visit hospitals routinely and are enrolled in study registries from previous studies may have a relatively severe and rapid progressive disease course. This may be the reason for the lower incidence observed in our population-based study, which is based on the NHIS database of almost all Korean citizens, and also a strength of this study compared to previous studies.Few studies have reported on the incidence of LC during the follow-up period for IPF. Ozawa et al. reported cumulative LC incidence rates of 3.3%, 15.4%, and 54.7% at 1, 5, and 10 years, respectively, in 103 IPF patients13. The median time from IPF diagnosis to LC development tended to be shorter in those aged ≥ 60 years, but there was no significant difference between the age groups.The cumulative incidence graph showed a constant incidence rate over the 5-year study period, while previous studies reported that the incidence rate increased until 3–4 years from IPF diagnosis and then decreased25. Lederer et al., in another review, proposed that annual low-dose CT should be performed according to the U.S. Preventive Services Task Force criteria for LC screening, and nodules should be managed according to risk group based on the established guidelines of the Fleischner Society1.Although there is no official guideline for LC surveillance till date, various suggestions have been proposed in previous reviews. Tzouvelekis suggested the performance of high-resolution computed tomography (HRCT) once a year in all IPF patients. For nodules with a diameter smaller than 8 mm, HRCT is suggested every 3–6 months. If HRCT shows progression of the nodule, and for nodules with a diameter of at least 8 mm, positron emission tomography-CT is recommended3, and the fact that the cumulative incidence rate was kept constant during the study period, it is suggested that all IPF patients undergo close HRCT screening.Considering previous reports, which state that the LC incidence in IPF patients is approximately eight times higher than in the general population after adjusting for smoking history26. A retrospective study reported that the incidence of LC was lower in IPF patients receiving pirfenidone27. Nintedanib was first approved in combination with docetaxel as a second line treatment for advanced non-small cell LC28. The anti-cancer effect of these two antifibrotic agents should be further investigated in both therapeutic and protective aspects.Another challenge associated with IPF in LC, in real clinical practice, is the identification of whether the antifibrotic agents that are used to reduce the degree of forced vital capacity decline in IPF patients have anti-cancer effects. Nintedanib and pirfenidone are two antifibrotic agents that have been approved for IPF treatment. A preclinical experimental study revealed that a combination of cisplatin and pirfenidone increases cell death rates and decreases cancer progression rates29. However, IPF is classified as a rare intractable disease in Korea and strictly controlled by the Korean NHIS for medical cost reductions. This may lead physicians to enter the diagnostic code with care. Second, data on confounding factors that may have affected the incidence and mortality of both IPF and LC, such as smoking, pulmonary function , and concomitant emphysema, were not available in the study. Further study is needed to confirm whether close HRCT surveillance for LC in IPF will help improve the mortality of IPF patients with LC.This study has several limitations. First, we defined IPF using the ICD-10 code assigned by healthcare providers; this may have reduced the diagnostic accuracy owing to inconsistencies with the diagnostic criteria defined by the International Consensus Statement of the American Thoracic Society and European Respiratory Society in 2011In conclusion, the present study revealed that the prevalence of LC in IPF patients was 6.4% and the cumulative incidence rates were 1.7%, 4.7%, and 7.0% at 1, 3, and 5 years, respectively, after IPF diagnosis. The 5-year survival rate was 15.6% in the IPF with LC group, which was significantly lower than that in the IPF without LC group. Our findings suggest the need for close HRCT surveillance for LC in all IPF patients.The National Health Insurance Service (NHIS) in Korea has provided health insurance services to all Korean citizens living in Korea since 2000. Consequently, a large amount of health-related data has accumulated in the NHIS database. To offer relevant and useful data for health researchers, the NHIS established a population database including data on socioeconomic status (household income), medical treatments, medical care institutions, and general health examinations since 2002. From the NHIS database, we identified IPF and LC based on International Classification of Disease, Tenth Revision (ICD-10) diagnostic codes. This study was approved by the Institutional Review Board and Ethics Committee of National Health Insurance Service of the Ilsan Hospital (IRB number: NHIMC 2019-1-291). All methods were performed in accordance with the Declaration of Helsinki.30. The ICD-10 code C34 was used for malignant neoplasms of the bronchus and lung. To estimate the cumulative incidence of LC in patients with newly diagnosed IPF and the time from IPF diagnosis to LC development, we excluded patients who were diagnosed with IPF in 2011 and analyzed those who were newly diagnosed with IPF after 2012. Mortality data were analyzed from 2012 to 2018.The NHIS database includes medical data on almost all South Korean citizens aged ≥ 40 years (about 50 million people) between 2011 and 2016. From this population, we identified patients visiting medical institutions with a diagnosis of IPF, coded as J84.18 according to the ICD-10. We excluded patients with ICD-10 codes for both IPF and connective tissue disease, owing to the possibility of interstitial lung disease being related to connective tissue disease. The ICD-10 codes for connective tissue disease were as follows: M05 for rheumatoid arthritis, M07 for psoriatic and enteropathic arthropathies, M30 for polyarteritis, M31 for other necrotizing vasculopathies, M32 for systemic lupus erythematosus, M33 for dermatopolymyositis, M34 for systemic sclerosis, M35 for other systemic involvement of connective tissue, and M45 for ankylosing spondylitis. The code J84.18 was classified as a rare intractable disease, and patients assigned to this code receive medical cost reductions from the NHIS by up to 10% of the total cost. Owing to the financial problems associated with rare intractable diseases, the ICD for these diseases has high sensitivity and specificityP values < 0.05 were considered statistically significant. All statistical analyses were performed using the SAS program, version 9.4 .Continuous variables were analyzed using the Student’s t-test, and categorical variables using Chi-squared distribution. Cumulative time-to-event distributions were estimated using the Kaplan–Meier method. Log-rank test was used to compare survival curves, and Cox proportional hazards regression analyses were conducted to assess the impact of LC on survival in IPF. In all cases, This study was approved by the Institutional Review Board and Ethics Committee of National Health Insurance Service of the Ilsan Hospital (IRB number: NHIMC 2019-1-291). Written informed consent was waived as the nature of retrospective study by IRB.Supplementary Table S1.


Moreover, non-covalent functionalization proved to be impactful in imparting an overall enhancement of the nanocomposite mechanical properties due to good bonding between graphene and epoxy matrix, also showing a greater roughness which is decisive in influencing the interface adhesion efficiency.In this paper, a non-covalent π–π interaction between graphene nanoparticles (G) and a pyrene-based molecule (py) has been successfully accomplished to give the functionalized nanofillers (G-py). The proposed modification has proven to be a winning solution aimed at safeguarding the graphene’s notable electronic properties, while promoting a more effective nanofiller dispersion attributable to a decrease in viscosity with consequent improvement of the rheological properties of the formulated nanocomposites filled with G-py. The electrical current maps of the G-py based epoxy composites, loaded with filler weight percentages both above and below the electric percolation threshold (EPT), were obtained by tunneling atomic force microscopy (TUNA) technique. The possibility to detect low currents also for the sample at lower concentration (0.1 wt%) confirms the good electrical performance of the nanocomposites and, consequently, the successful performed functionalization. The non-covalent modification significantly improves the thermal stability of the unfunctionalized G of about 70 °C, thus causing an increase in the composite oxidative thermostability since the evolution of CO From a direct comparison between these conductivity values, it can be deduced that the non-covalent functionalization of G by pyrene derivative molecules to give G-py, not only preserves the electrical properties of the nanocomposites, but also leads to an increase in the value of the electrical conductivity of two orders of magnitude with respect to the resin loaded with the same 1 wt% of unfunctionalized G. The percentage of 1 wt%, calculated with respect to all the components of the epoxy matrix (R), has been chosen because it is above the electrical percolation threshold, which is in the range 0.025–0.1 wt% for the G based nanocomposites [−14 S/m. As main result of the morphological investigation, the chemical functionalization was found to be decisive in preventing the particle agglomeration during the dispersion phase, thus allowing optimization of the preparation process [Graphene is a two-dimensional spmaterial . Becausematerial , and higmaterial , graphenmaterial ,6,7,8,9.material . Howevermaterial . In thismaterial ,13. Covamaterial , substituctivity . Insteaductivity . In thismposites . The unf process ,19,20 of process  and also2 to shift to higher temperature values. Moreover, in this paper, non-covalent functionalization allows obtaining good mechanical properties as a result of an effective bond between the filler and the matrix, thus confirming its ability in acting as a strategic way to control the properties and improve the performance of graphene in various advanced applications [In addition, the rheological properties of the epoxy samples filled with unfunctionalized G and functionalized G-py nanoparticles are related to the material’s microstructure , the disications .2Cl2 dry. The functionalized G-py sample (1.080 g) was obtained after filtering, washing with 30 ml of the CH2Cl2, and drying throughout the night under vacuum the mixture which was kept under stirring for 2 h at room temperature.By exfoliating natural graphite characterized by a high surface area with an average diameter of 500 μm ), we obtained conductive graphene nanoparticles (G). In particular, the exfoliation procedure is based on intercalation of natural graphite in a solution of nitric and sulphuric acids, followed by an abrupt treatment at high temperature (900 °C) in a reactor to obtain the expansion of graphene layer spacing . The perBy mixing 80 wt% of the tetraglycidylmethylenedianiline (TGMDA) with 20 wt% of the reactive diluent 1-4 butanedioldiglycidyl ether (BDE) which is able to expedite the dispersion step of nanofiller , and, th−1. The Raman analysis was recorded at room temperature. An excitation wavelength of 514 nm and a laser power of 30 mW was used.A micro-Raman spectrometer Renishaw inVia  was used to perform a Raman spectral mapping of both the functionalized G-py and the pristine G in the range 100–3200 cmField emission scanning electron microscope (FESEM) pictures of the two nanofillers G and G-py and their corresponding nanocomposites were acquired using SEM . Before the examination by FESEM, thin slices of solid samples were cut and subjected to an etching procedure with an oxidizing solution ,10,17 toA Keithley 6517A multimeter and an ammeter HP34401A  were used to measure the direct current (DC) conductivity values reported in this paper for some of the graphene-based nanocomposites analyzed.−1 were used. TUNA control parameters such as DC sample bias between 1 and 3 V, 1pA/V current sensitivity, 0.500 Hz s−1 scan rate, 512 samples/line were set for image acquisition. It should be pointed out that the TUNA nanoelectrical characterization was realised without using conductive silver paste which guarantees suitable electrical contacts of the sample with the ground [TUNA exploration was accomplished in a contact mode on the graphene-based nanocomposites after the etching procedure. An electrically conductive tip of 20 nm and platinum-coated probes with nominal spring constants of 35 Nme ground ,21. BrukA Physica MCR 301 (Anton Paar) rotational rheometer  fitted with a parallel plate geometry  was used to carry out the rheological measurements on the liquid systems, before they undergo the curing process. In particular, in this work, we show the rheological results of the ternary TGMDA/BDE/DDS mixture (labelled R), of the RY%G dispersions, where the Y values are 0.5, 0.75 and 1 wt% of the unfunctionalized graphene content, G, and of the RY%G-py dispersion, where the Y values are 0.5, 0.75 and 1 wt% of G-py.The linear viscoelastic region was determined by strain sweep tests, at the frequency of 1 rad/s and at the temperatures of 25, 50, and 75 °C.The linear viscoelastic (LVE) limit for the uncured epoxy matrix R (TBD) is 40% at T = 25 °C, LVE limit = 30% at T = 50 °C, and LVE limit = 10% at T = 75 °C.The linear viscoelastic limit for R0.5%G based epoxy sample dispersions with unfunctionalized graphene G are: LVE limit for the R0.5%G = 1% at T = 25 °C, LVE limit for the R0.5%G = 2% at T = 50 °C, LVE limit for the R0.5%G = 10% at T = 75 °C.The linear viscoelastic limit for R0.75%G based epoxy sample dispersions with unfunctionalized graphene G are: LVE limit for the R0.75%G = 0.005% at T = 25 °C, LVE limit for the R0.75%G = 0.07% at T = 50 °C, LVE limit for the R0.75%G = 0.3% at T = 75 °C.The linear viscoelastic limit for R1%G based epoxy sample dispersions with unfunctionalized graphene G are:R1%G = 0.002% at T = 25 °C, LVE limit for the R1%G = 0.02% at T = 50 °C, LVE limit for the R1%G = 0.1% at T = 75 °C.Moreover, the linear viscoelastic limit the R0.5%G-py dispersion with pyrene-functionalized graphene G-py are: LVE limit for the R0.5%G-py = 5% at T = 25 °C, LVE limit for the R0.5%G-py = 5% at T = 50 °C, LVE limit for the R0.5%G-py = 30% at T = 75 °C.Then, the linear viscoelastic limit the R0.75%G-py dispersion with pyrene-functionalized graphene G-py are: LVE limit for the R0.75%G-py = 5% at T = 25 °C, LVE limit for the R0.75%G-py = 5% at T = 50 °C, LVE limit for the R0.75%G-py = 5% at T = 75 °C.Finally, the linear viscoelastic limit the R1%G-py dispersion with pyrene-functionalized graphene G-py are: LVE limit for the R1%G-py = 5% at T = 25 °C, LVE limit for the R1%G-py = 5% at T = 50 °C, LVE limit for the R1%G-py = 5% at T = 75 °C.−2 to 102 rad/s.Frequency sweep tests at 25 °C, 50 °C, and 75 °C were performed, within the linear viscoelastic region, varying the angular frequency from 103. A variable flexural deformation in three points bending mode was applied. The mechanical tests were carried out in a temperature range between −150 °C to 350 °C at the scanning rate of 3 °C min−2, frequency of 1 Hz, and displacement amplitude of 0.03 mm.Dynamic mechanical properties were measured with a Tritec 2000 DMA . The sample dimensions were 2 × 10 × 35 mm−1. The Cure Degree (DC) of the samples was assessed using the calorimetric data [A Mettler DSC 822 differential scanning calorimeter  in a flowing nitrogen atmosphere was used to carry out thermal characterization between 0 and 300 °C with a scan rate of 10 °C minric data ,22,26.A Mettler TGA/SDTA 851 thermobalance  was used to carry out the thermogravimetric analysis (TGA). The temperature range between 0 °C and 1000 °C at a 10 °C/min heating rate under both nitrogen and air flows was used to heat the formulated samples.The functionalized G-py nanoparticles were characterized by Raman spectroscopy. The G-py spectra were compared with those of unfunctionalized G to obtain information on the degree of structural ordering and therefore the bonding states of carbons in the graphene structure. −1, distinguishable with different intensity for all the samples. In the case of less crystalline graphite, further bands at ~1350–1355 cm−1, 1500 cm−1, and 1622 cm−1 are detectable. The D band at ~1350 cm−1 is induced by the disordered structure of graphene sheets. The presence in the second-order region (2200–3300 wavenumbers) of the 2D or G’ band at ~2700 cm−1, due to overtones and combinations of the disorder-induced bands, is characteristic of graphite crystallinities. G-py sample exhibits a pattern similar to the G sample. For both nanofillers, the very small difference in the intensity of the bands relative to each sample is due to the local region where the spectrum was detected. This difference is due to the fact that on the edge of the nanoparticles a greater number of defects is present. A general conclusion of this investigation is that the non-covalent modification did not destroy the layered structure of pristine G nanofiller, thus proving that non-covalently functionalized G-py can be successfully employed to formulate the functional nanocomposites for structural applications.In the Raman spectrum first-order region (1100–1800 wavenumbers), we can observe the main graphite band, named the G band, at ~1580 cmFESEM pictures of the pristine G and functionalized G-py nanofillers are shown in We can clearly observe that for both G and G-py samples, the exfoliated graphite sheets exhibit a highly fluffy morphology representative of thermally treated graphite. Furthermore, FESEM images show the folds and wrinkles present on the surface of the relatively large  and uniform graphene platelets. This confirms, as the Raman analysis, that the graphene-layered structure is not destroyed by non-covalent functionalization.The dispersion of the nanofiller in the polymeric matrix was analysed by the FESEM technique on sample surfaces that have previously undergone the acid attack of an etching solution which, by consuming the resin, allowed to discover the nanocharge. From −3 S/m obtained for the G based epoxy nanocomposite R1%G, loaded at the same loading concentration of 1 wt%, which corresponds to the percentage above the electrical percolation threshold. The enhancement in the electrical conductivity is most likely due to a better dispersion of the filler and the nature of the functionalizing py compound.Surface texture knowledge is an important question when aiming to comprehend the nature of the material surface and it is of primary importance when there is interest in verifying the adhesion effectiveness at the interface between the matrix and the nanoparticles. The mechanical interaction associated with the surface roughness can be effectively evaluated by means of TUNA technique which allows deriving quantitative measurements of roughness using two of the most significant height parameters, namely the roughness average (Ra), which is the arithmetic mean of the absolute values of the height of the surface profile, and the root mean square roughness (Rq) which is analogous to the roughness average (Ra), with the only difference being the mean squared absolute values of surface roughness profile. The Rq is more sensitive to peaks and valleys than the average roughness due to the squaring of the amplitude in its calculation .−1. Regarding the nanocomposite R0.1%G-py, the roughness values assessed for the TUNA pictures shown in the In this work, nanoscale roughness Ra and Rq values of the prepared composites R0.1%G-py see  and R1%GRegarding the nanocomposite R1%G-py, the roughness values assessed for the TUNA pictures shown in the In order to fully understand the influence of the non-covalently functionalized carbon nanofiller G-py on the mechanical behavior of the resin R and G-based nanocomposites, DMA was performed. In a context in which the hydrophobic nature of graphene makes it incompatible with most organic polymers and tend to irreversibly agglomerate itself, the modification of graphene nanoparticles by non-covalent method is becoming increasingly significant for the solution of this problem. In this regard, particular importance is given to π−π interactions because of their strength, comparable to covalent bonding  but withg) which is around 264 °C for the R0.5%G-py nanocomposite  in air of the unfunctionalized G and non-covalently functionalized G-py nanofillers is shown in In order to better understand and interpret the thermogravimetric data for the different analyzed systems, the TGA trend . This increase is most likely due to strong adsorption of nitrogen molecules, which are geometrically linear and characterized by small dimensions, on and among thin functionalized graphene layers.From the TGA curves, it can be clearly seen that for the functionalized sample G-py (see the black curve) the beginning of the thermodegradation phenomenon moves to a higher temperature of about 70 °C compared to unfunctionalized G (see the blue curve). More precisely, the non-covalent functionalization of graphene with pyrene derivative significantly improves the thermal stability of the starting unfunctionalized nanocharge G, effectively increasing the oxidative thermostability of the composite because the evolution of COThe curing degree (DC) has been gained in the dynamic and isothermal regime. For all the analyzed formulations, the curing reactions are active in the range between 125 °C and 250 °C in the dynamic regime. DC values of the pristine G and functionalized G-py based nanocomposites cured under isothermal heating conditions, shown in d) (in air and nitrogen) for cured (200 °C) epoxy resin (R) filled with G and G-py nanoparticles at different percentages by weight. In particular, the thermodegradation temperature (Td) referred to a sample weight loss of 5% for all the samples containing both pristine G and functionalized G-py nanofillers.d at about 360 °C in both inert and oxidative environment, as it can be clearly seen by observing the graph relating to the zoom of the initial values of Td.Samples cured in the oven at 200 °C show similar values of TThe rheological results for the liquid dispersions containing 0.5 wt%, 0.75 wt% and 1 wt% of the unfunctionalized (G) graphene nanoparticles in the R uncured resin, at the temperature of 50 °C, are shown in In The rheological results can also be analysed in terms of complex viscosity (η*) vs shear stress (τ) and they are shown in From the graphs shown in Moreover, it is noteworthy that the presence of edge-carboxylation of the graphitic material decreases the rheological percolation threshold to values similar to those observed for the mono-dimensional MWCNTs fillers .Finally, the complex viscosity (η*) vs. frequency (ω) for the liquid dispersions containing an amount of 0.5 wt% of the unfunctionalized (G) and functionalized (G-py) graphene nanoparticles in the R uncured matrix, at the temperatures of 25 °C, 50 °C, and 75 °C, are compared in 3). TUNA analysis was carried out using G-py weight percentages both below and above the EPT in order to investigate the electrical behavior of the conductive nanodomains of the epoxy/graphene systems. In particular, for the lowest concentration equal to 0.1 wt% of G-py, in most of the sample domains, no electrically conductive paths are observed, while for the highest concentration equal to 1 wt% of G -py, the presence of a conductive network at the nanoscale level with efficient adhesion to the interface clearly indicates that it is above the EPT. It is important to emphasize that the possibility to detect low currents also for the sample at lower concentration (0.1 wt%) confirms the good electrical performance of the nanocomposites and, consequently, the successful performed functionalization. These excellent electrical results are in perfect agreement with the rheological results. In fact, the inclusion of a functionalized G-py nanofiller amount of 0.5 wt% caused the decrease in the complex viscosity of the unfilled epoxy resin R, while instead the same quantity of unfunctionalized nanofiller G resulted in an increase of its viscosity. This aspect is of crucial importance from the industrial point of view since the use of non-covalently functionalized G-py allows to considerably simplify the steps of the preparation process of the nanocharged epoxy samples, thus favoring also the impregnation of the plies of carbon fiber fabrics. This is a problem that is by no means insignificant if we consider that nanofilled aeronautical resins used to impregnate carbon fibers contain a percentage of nano-charges capable of producing samples in the nanofiller’s concentration range beyond the EPT. A significant improvement in the thermal stability of the unfunctionalized graphene G of about 70 °C was registered, thus determining an increase in the composite oxidative thermostability since the evolution of CO2 shifts to higher values. Moreover, non-covalent functionalization proved to be particularly effective in conferring outstanding mechanical properties on the nanocomposites thanks to the strong interfacial adhesion between graphene-matrix and satisfactory dispersion of graphene nanoparticles inside the epoxy matrix.In this work, we have demonstrated that the non-covalent functionalization including mainly π–π interactions and hydrogen bonding represents a tactical way to control the properties and ameliorate the fulfillment of graphene nanoparticles characterized by carboxylated groups at the edge of graphene layers or graphitic blocks in advanced applications. Understanding the rheological behavior is of great importance for optimizing the manufacturing process of the structural nanofilled epoxy resins, where the amount of graphene is over the electrical percolation threshold (EPT) and for obtaining information about whether the structure is percolated. From the direct comparison between the direct current electrical conductivity values, we have found that the non-covalent functionalization of graphene G by pyrene derivative molecule, giving G-py sample, not only preserves the electrical properties of the nanocomposites, but also leads to an increase in the electrical conductivity value of two orders of magnitude with respect to the resin loaded with the same percentage of 1% by wt of unfunctionalized G nanofiller. The enhancement in the electrical conductivity is most likely due both to a more effective dispersion of the nanofiller in the matrix and the nature of the py functionalizing compound. In fact, the py compound is characterized by a structural nature very similar to a small portion of graphene. This small part of py compound may locally compensate for the reduced attitude in the electron conduction of zones of nanofiller characterized by structural defects (with a higher percentage of carbon atoms hybridized sp


Scaffold-based bone tissue engineering is the most relevant approach for critical-sized bone defects. It is based on the use of three-dimensional substrates to provide the appropriate biomechanical environment for bone regeneration. Despite some successful results previously reported, scaffolds were never designed for disease treatment applications. This article proposes a novel dual-functional scaffold for cancer applications, comprising both treatment and regeneration functions. These functions are achieved by combining a biocompatible and biodegradable polymer and graphene. Results indicate that high concentrations of graphene enhance the mechanical properties of the scaffolds, also increasing the inhibition on cancer cell viability and proliferation. To design effective PCL-based scaffolds, we investigated the degradation kinetics of such scaffolds as a function of scaffold topology,18 the effect of processing conditions on the morphological development/microstructure formation during the printing process,20 and surface modification strategies to improve cell attachment, proliferation, and differentiation.21 Due to the piezoelectric and reverse piezoelectric properties of bone, our group also developed strategies to induce electroconductive properties on PCL-based scaffolds by adding a low concentration of conductive materials such as graphene.16Novel dual-function scaffolds are mainly made with a biodegradable and biocompatible polymer. This polymer is poly, showing that toxic effects are concentration-, time- and shape-dependent.23 Graphene has been reported to induce oxidative stresses and cell function assays, and confocal microscopy images indicated that reactive oxygen species induced by the carbon atoms on the edge of graphene can damage DNA.24–26 Moreover, authors also reported that the few-layer graphene dispersions have a specific killing ability on monocytes.27 Graphene also showed an effective ability to inhibit the migration and invasion of human breast and prostate cancer cells, as well as mouse melanoma cells.28Previously reported studies demonstrated that graphene, 2D single-atom thick sheets of carbon atoms bound in hexagonal lattice structures, shows high affinity to glioblastoma cells leading to the adhesion of graphene to the cell's body and, consequently, cell membrane damage. Other studies also reported different levels of cytotoxicity both 14 will be gradually released, inducing the apoptosis of the remaining cancer cells. This effect can be controlled by the graphene content, and both crystallinity and crystal orientation of PCL in the printed fibers, which strongly depend on processing conditions. After the degradation of these initial layers that are responsible for the treatment function of the scaffold, PCL layers (core part of the scaffold) will be revealed. These layers must be able to provide the necessary biomechanical environmental conditions to sustain the recruitment of healthy cells (bone cells or stem cells) and cell attachment, proliferation, and differentiation (regeneration function).The potential cytotoxicity of high graphene contents on a PCL matrix are explored in this article to create the first layer of the novel dual-function scaffolds . Graphen9 The obtained graphene nanosheets were mixed with PCL pellets  through a melt-blending process by using different graphene concentrations . The PCL pellets and graphene nanosheets were heated to 150°C and mixed together in a crucible for 30 min. The material was stirred for 30 min to homogeneously disperse the graphene. After cooling down for 3 h, the mixed materials were then cut into pellets and prepared for printing.Graphene nanosheets were synthesized from graphite by water-assisted liquid-phase exfoliation, as reported earlier.14 The following design and processing parameters were considered:Design parameters:Laydown pattern: 0°/90°.Square pores.Pore size: 350 μm.Filament diameter: 330 μm.Slice thickness: 270 μm.Processing parameters:Melt temperature: 90°C.Screw rotation velocity: 8 rpm.Deposit velocity: 12 mm/s.Pressure: 6 bar.Scaffolds were produced by a screw-based additive manufacturing system 3DDiscovery™ Evolution Bench-top  , which allows to print fibers with a uniform dispersion of graphene as previously reported by micro-Raman spectroscopy.Thermogravimetric analysis (TGA) was used to determine the exact amount of graphene present in the scaffold. Tests were performed by using the Thermal Analysis Q500 analyzer (TA Instrument) with PCL scaffolds and graphene-loaded scaffolds. Scans were performed in an air atmosphere with an airflow of 60 mL/min and temperature ranging from 35°C to 560°C at a 10°C/min ranging rate. TGA tests were performed by using samples with around 1 g of weight placed in platinum pans. The weight change of the samples was monitored by using the TA Universal Analysis 2000 software (TA Instrument).Morphological characterization of the scaffolds was performed through scanning electron microscopy (SEM). The Hitachi S3000N system  was used to capture images of both the top surface and cross-section of the scaffolds, using an accelerating voltage of 10 kV. Before image capturing, the scaffolds were cut into 4 mm blocks and coated with a thin layer of metal (10 nm gold) by using the EMITECH K550X sputter coater . The obtained images were processed by ImageJ (NIH).F and corresponding displacement Δh were measured by sensors while the samples were compressed, and they were then transformed into stress σ and strain ɛ values. The compressive modulus and compressive strength of the scaffolds were calculated and plotted by Origin (OriginLab).Uni-axial compression tests were conducted on the INSTRON X testing system  with a 100 N load cell. The scaffolds were cut into blocks of 3 mm of width, 3 mm of length, and 4 mm of height. Compression tests were performed in dry state with the strain ranging from 0 to 0.3 mm/mm (30%) and a displacement rate of 0.5 mm/min. Force In vitro biological studies were conducted by using both human adipose-derived stem cells (hADSCs) (Invitrogen) and sarcoma osteogenic (Saos-2) cells (ATCC). Cells were cultured in the corresponding medium  in T75 cell culture flasks  at standard condition  in a New Brunswick® Galaxy 170 R incubator (Eppendorf). Cells were harvested at approximate 80% confluency with 0.05% trypsin-ethylenediaminetetraacetic acid (Invitrogen) before cell seeding. Cells ranging from passage 6 to 8 were considered for biological evaluation.Before cell seeding, scaffolds were sterilized in 80% ethanol (Thermo Fisher Scientific) for 4 h, transferred to a 24-well plate, and rinsed three times with Dulbecco's phosphate buffered saline (Thermo Fisher Scientific). Fifty-thousand cells (counted by Cellometer Auto 1000 Bright Field Cell Counter [Nexcelom Bioscience]) in 0.8 mL corresponding medium were seeded on each scaffold sample and empty well (control group).29 At each particular time point, 0.8 mL of medium containing 0.001% Alamar Blue  was added to each well and incubated for 4 h. Then, 150 μL fluid from each well was transferred into a 96-well plate and the fluorescence intensity was measured by a Multi-Detection Microplate Reader Synergy HT (BioTec) (excitation wavelength of 540 nm and emission wavelength of 590 nm).Cell viability was evaluated at 1, 3, and 7 days after cell seeding by using the Alamar Blue assay, which can quantitatively monitor the metabolism and cytotoxicity of the cells.The SEM images of both the top surface and cross-section of the scaffolds are presented in 30–33Biological evaluation results are presented in These results show that the addition of graphene fillers can reduce the survival rate of both hADSCs and Saos-2 cells, and the PCL/graphene scaffolds exhibit a greater inhibition ability on Saos-2 cells than on hADSCs. Besides, cells can grow and proliferate well on PCL scaffolds between days 1 and 7, showing no significant inhibition effect.in vitro studies and other assays  will be considered before the in vivo study. Further, long-term in vitro and in vivo degradation tests will also be performed. In general, results seem to indicate that the proposed dual-functional scaffold can be a valid solution for bone cancer applications, without the secondary effects of current clinical approaches focusing on treatment and not on both treatment and regeneration.This article proposes for the first time a novel dual-functional 3D scaffold for bone cancer treatment and regeneration post-treatment. These scaffolds comprise external layers made of PCL and high contents of graphene and internal PCL layers. Results show the inhibitory effect of graphene, particularly on Saos-2 cells, and the high load of cell attachment and proliferation on PCL. The addition of graphene also contributes to increasing the compressive modulus and compressive strength, thus making it possible to achieve values similar to the human trabecular bone. This is particularly relevant for the initial stages where the scaffold must be able to support the loads in the host environment. All scaffolds were produced by using the same processing conditions; the consequences of rheological changes due to modifications on the material composition, differences in terms of filament diameters and pore size between printed scaffolds and designed ones were observed. These will be solved in the future by adjusting the processing conditions depending on printability and rheological characterization of the material. Besides, a wider range of materials, including graphene oxide and selenium, will be further investigated. Surface modification will also be considered to allow the incorporation of biomolecules or targeted cancer treatment drugs into the scaffolds. In terms of biological performance, longer


Intense particle beams generated from the interaction of ultrahigh intensity lasers with sample foils provide options in radiography, high-yield neutron sources, high-energy-density-matter generation, and ion fast ignition. An accurate understanding of beam transportation behavior in dense matter is crucial for all these applications. Here we report the experimental evidence on one order of magnitude enhancement of intense laser-accelerated proton beam stopping in dense ionized matter, in comparison with the current-widely used models describing individual ion stopping in matter. Supported by particle-in-cell (PIC) simulations, we attribute the enhancement to the strong decelerating electric field approaching 1 GV/m that can be created by the beam-driven return current. This collective effect plays the dominant role in the stopping of laser-accelerated intense proton beams in dense ionized matter. This finding is essential for the optimum design of ion driven fast ignition and inertial confinement fusion. A detailed understanding of particle stopping in matter is essential for nuclear fusion and high energy density science. Here, the authors report one order of magnitude enhancement of intense laser-accelerated proton beam stopping in dense ionized matter in comparison with currently used models describing ion stopping in matter. Fast ignition (FI) relies even more on a detailed understanding of ultrahigh-current ion stopping in matter, which is therefore considered as a fundamental process of utmost importance to nuclear fusion. In the fast ignition scheme9, a short and intense pulse of energetic charged particles—electrons, protons, or heavy ions—generated by an ultra-high-intensity laser, is directed toward the pre-compressed fusion pellet. The charged-particle beam requirements to achieve ignition have been discussed and studied in detail previously14 based on single-particle stopping theory. However, the collective effects induced by high-current charged-particle beams could alter significantly the projected range, the magnitude of energy deposition, and therefore change the requirements for ignition correspondingly. Besides, in the cases of ion beam-driven inertial confinement fusion and high-energy density science, which require ultrahigh beam intensity from accelerators19, no collective effects on ion stopping processes due to high beam intensity are considered nor—to the best of our knowledge—were they reported in any previous experiments.Alpha-particle stopping in dense ionized matter is essential to achieve ignition in inertial confinement fusion25. In past decades, numerous theoretical models32, some of which can be considered to be further developments of the early work of Bethe28 and Bloch29, are built to describe individual charged particle stopping in dense ionized matter. Only recently experiments with sufficient precision were carried out with dense ionzied matter to distinguish between different models35. In these experiments, incident particles are generated from laser-induced nuclear reactions34, or from traditional accelerators35. Hence the beam intensity was low, and the individual ion stopping theories can be discriminated36.Since the discovery of alpha decay and the availability of energetic fission fragments, it became interesting to study fast particle stopping processes in matter18–1022 W/cm2) have opened up perspectives in many fields of research and application44. By irradiating a thin foil with ultra-high-intensity lasers, an ultrahigh accelerating field (1 TV/m) can be formed and multi-MeV ions with high intensity (1010 A/cm2) in short timescale (~ps) are produced53. Such beams provide experimental opportunities to investigate the beam-driven complex collective phenomena59. In particular, the stopping power for these intense beam could be orders of magnitude higher than that for individual particles if the beam intensity is high enough63. In our previous experiment, we sent the laser-accelerated ion beams directly into the plasma target, and observed that the energy spectra of the ions were significantly downshifted after passing though the dense plasma64. This energy downshift was far beyond the Bethe–Bloch predictions 26, standard stopping model (SSM)32. Through PIC simulation, we attribute the high degree of enhancement to a strong decelerating electric field induced by the intense proton beam. This collective effect is the primary cause for the enhanced stopping, and it is likely to have a major impact on nuclear fusion scenarios like fast ignition, alpha-particle self-heating, as well as ion driven inertial confinement fusion.In this article, we improve the precision of the measurement by using a magnetic dipole to trim out a quasi-monoenergetic proton beam. The dense ionized target is produced by irradiating a tri-cellulose acetate (TCA) foam sample with soft X-rays from a laser-heated hohlraum. Thus the temperature and density are homogeneous across the ionized target. This state can be maintained for a period of more than 10 ns. This period is two to three orders of magnitude longer than the beam duration and the beam-plasma interaction timescale. Therefore, the target can be considered to be quasi-static. This kind of experimental scenario allows for precise measurement of intense proton beam stopping in dense ionized matter. We observed that the energy loss is enhanced by one order of magnitude in comparison  to the predictions from individual-proton stopping theories, Bethe–Bloch1+) and carbon ions with different charge states . They originate at the backside of the target by means of the target normal sheath acceleration (TNSA). The predominant particle species is H1+, because the charge- to-mass ratio is maximum for this species, and is, therefore, more effectively accelerated than the lower charge-to-mass ratio species of carbon ions. The TNSA mechanism results in a broad range of particle energies, which is not favorable for quantitative analysis of the particle energy loss. A magnetic dipole, with entrance and exit slits, was used to generate a monoenergetic beam. The ions, spatially collimated by the 500 μm entrance slit, are dispersed laterally by the magnetic dipole according to their specific p/q value, where p and q are the particle momentum and charge, respectively. A second 500 μm exit slit, selects the quasi-monoenergetic ion pulses. The selected ions consist of different particle species, with similar p/q value, they have, however, different velocities and therefore arrive at the target pulse by pulse with different time delay. In the current case, the C4+ ion pulse lags behind proton pulse by about 30 ns at the plasma target, and C3+, C2+, and C1+ pulses are delayed more, therefore the laser-accelerated carbon ions have no influence on the proton beam stopping measurement.The experiment was carried out at the XG-III laser facility of Laser Fusion Research Center in Mianyang. The experimental layout is displayed in Fig. 9H16O8, density of 2 mg/cm3 and thickness of 1 mm) to produce ionized matter. The hydrodynamic response of the heated foam target under this kind of scheme has been very well-investigated and the state has been well characterized67. Once heated by soft X-rays from hohlraum radiation, the material expansion occurs inside the target between the sponge-like structures. This micro expansion leads to target homogenization, while the volume and density of the entire target stay constant for more than 10 ns. Therefore, homogeneous, ns-long-living, and quasi-static ionized matter is generated. Unlike producing ionized matter through direct heating by high-power lasers—in which case strong electromagnetic fields are generated in the target and will greatly influence the proton transportation behavior70—here the electromagnetic fields resulted from the heating process can be neglected.A gold hohlraum converter was used to generate soft X-rays by interaction of a ns laser pulse (150 J), with the hohlraum walls. The X-rays subsequently irradiated and heated the foam target E/dx = (dE/dx)collision + (dE/dx)collective. The first term (dE/dx)collision describes the collisional stopping induced by binary interaction of the individual projectiles with the individual particles in the plasma. The second term (dE/dx)collective describes the collective stopping induced by the beam-driven electric fields. (dE/dx)collision consists of contributions from free electrons and plasma ions. The ionic contributions for partially ionized plasma include two parts, bound electrons and nuclei. In the current regime, where the protons are much faster than the thermal electrons, the contribution of the nuclei to (dE/dx)collision can be neglected77. Here in this article the nuclear stopping is excluded.The energy loss of intense ion beam in ionized matter is composed of two terms as dIn Fig. 79.In order to understand this enhanced stopping, both collective electromagnetic effects and close particle–particle interactions need to be taken into account. The most appropriate tool to simulate the conditions of the experiment is the particle-in-cell method (PIC), which in recent years has established itself as a state-of-the-art method for solving problems of kinetic plasma physics80, which is able to simulate intense beam-plasma interaction in a self-consistent way, which contains both close collisions and collective electromagnetic fields (see details in “Methods”). The simulation assumes, the incident proton beam to have Gaussian distribution in space and time, with a beam duration of 1 ps and a transverse extension of 1 mm. The energy spectrum is also assumed to be Gaussian, with the peak of the energy distribution at 3.36 MeV and FWHM of 0.10 MeV. The measured ionized target parameters were used as simulation input. The simulation was carried out in Z–Y Cartesian geometry with beam propagating along the Z direction. The size of the simulation box was 1.2 mm × 2.5 mm, with a grid size of 0.75 μm × 25 μm.We used the recently developed PIC code LAPINS16 cm−3, which corresponds to high-current case of 3 × 107 A/cm2, Fig. Ez induced by the beam-driven return current after a propagation distance of about 0.3 mm. A strong decelerating field approaching 109 V/m is generated, and contributes to the proton stopping. The proton energy spectrum after passing through 1 mm of plasma is shown in Fig. 82, where the spatial structure of the electric field is determined by the plasma density. Here the plasma wakefield wavelength is much smaller than the beam length, therefore the wakefield-induced collective acceleration and deceleration cancel out. The central energy of proton spectrum is downshifted by 0.36 MeV after passing through the plasma. As shown in Fig. 11 cm−3 and 8 × 1015 cm−3, which are defined as low- and intermediate-current cases, respectively. For the low-current case, the beam-induced longitudinal electric field Ez after propagating for 0.3 mm in the plasma is shown in Fig. Given the incident proton beam with density of 8 × 10E/dx)collision and (dE/dx)collective. Bethe–Bloch, LP, SSM models, and PIC simulation for low-current case give similar predictions for (dE/dx)collision, which is one order of magnitude lower than the experimental data. PIC simulation for high-current cases shows that when sending a very dense ion bunch into the plasma, strong electric fields can be induced, and the ion bunch is imbedded in the deceleration field. This leads to a significant enhancement of the energy loss, which fairly well explains our observation.In all, the energy loss of laser-accelerated intense proton beam in dense ionized matter consists of  and then the velocity of each particle is replaced by the newly calculated one.In the calculations, three steps are made iteratively: (i) pair of particles are selected randomly in the cell, i.e., either electron–electron, electron–ion, or ion–ion pairs; (ii) for these pair of particles, the binary collisions are associated with changes in the velocity of the particles within the time interval In order to contain both bound and free electrons’ contribution into the binary collision model, we here take the collision frequency between ions and electrons, in the above (ii) step, as,A is the atomic number of stopping medium, Z is the ionization degree of background plasmas, ni is the nucleus density of stopping medium, me is the electron mass, γ is the relativistic factor of the projected ions, β is the velocity of projected ions, Zb is the effective charge state of injected ion beams, which equals ‘1’ for the case of protons in our present studies. In Eq. /Z defines the ratio of bound electrons’ contributions. For fully ionized plasmas, Z → A, the collision frequency between ions and electrons converges tomentclass2pt{minimZ → 0, in contrast, the frequency isFor neutral atoms, At the low-temperature limit, when all electrons are bound at the nucleus, the calculated stopping powers converge to the NIST ones with the average ionization degree approaching zero as the stopping powers of cold materials can be well calculated by Bethe–Bloch formula. With the increase of temperature, more and more bound electrons are ionized, giving rise to an increased stopping power to cold matter. When the temperature is further increased, with ionizations reaching the maximum, lowered stopping power is observed, which is due to the suppression of collision frequency between projected proton beam and hot plasmas in the target.79. To take into account collective electromagnetic effects, the background electron inertia is neglected, and instead the background return current is evaluated by the Ampere’s law Je = (1/2π) ∇ × B − (1/2π)∂E/∂t − Jb − Ji, where B is the magnetic field, E is the electric field, Jb is the injected beam current, and Ji is the background ion current. Applying the continuity equation  ∇ ⋅ J + ∂ρ/∂t = 0 with the total current J = Jb + Ji + Je, where ρ is the charge density, the Poisson equation  ∇ ⋅ E = 2πρ is rigorously satisfied. The electric fields are then obtained from Ohm’s law, E = ηJe − ve × B, where ve is the background electron velocity, and η is the resistivity. Taking advantage of the Monte Carlo collision model, resistivity η is obtained by averaging over all binary collisions at each time step for each simulation cell. Finally, Faraday’s law is used to obtain the magnetic fields ∂B/∂t = − ∇ × E. This field solver, which couples Ampere’s law, Faraday’s law, and Ohm’s law, can completely remove the numerical heating and reduces significantly the numerical expense. With these advantageous features a unique tool is at hand, which can self-consistently model transport and energy deposition of intense charged particles in dense ionized matter.Simulation of large scale plasmas often results in an intractable burden on computer power. Therefore, instead of solving the full Maxwell’s equations, we combine the PIC method with a reduced modelSupplementary InformationPeer Review File


Viral infections alone are a significant cause of morbidity and mortality worldwide and have a detrimental impact on global healthcare and socio‐economic development. The discovery of novel antiviral treatments has gained tremendous attention and support with the rising number of viral outbreaks. In this work, carbonaceous materials, including graphene nanoplatelets and graphene oxide nanosheets, were investigated for antiviral properties. The materials were characterized using scanning electron microscopy and transmission electron microscopy. Analysis showed the materials to be two‐dimensional with lateral dimensions ranging between 1 and 4 µm for graphene oxide and 110 ± 0.11 nm for graphene nanoplatelets. Antiviral properties were assessed against a DNA virus model microorganism at concentrations of 0.5, 1.0 and 2.0 wt/v%. Both carbonaceous nanomaterials exhibited potent antiviral properties and gave rise to a viral reduction of 100% across all concentrations tested. Graphene oxide nanosheets were then incorporated into polymeric fibres, and their antiviral behaviour was examined after 3 and 24 hr. A viral reduction of 39% was observed after 24 hr of exposure. The research presented here showcases, for the first time, the antiviral potential of several carbonaceous nanomaterials, also included in a carrier polymer. These outcomes can be translated and implemented in many fields and devices to prevent viral spread and infection. They cause infection by penetrating and reproducing inside living host cells, consequently causing cellular damage and illness. Viruses enter the body through all possible routes and spread from one person to another through direct or indirect contact with the pathogen Baron, . VirusesEfforts on the next generation of antivirals have been focused on nanomaterials, particularly metallic nanoparticles  were investigated. The carbonaceous nanomaterials were then incorporated into polymeric fibres, and the antiviral activity of the resulting fibres (carriers) was studied to determine whether or not the materials remain effective.In this research, the inhibitory effects of graphene nanoplatelets and graphene oxide nanosheets on 22.12.1.1Graphene oxide nanosheets were prepared from graphite powder following a modified Hummers' method  (PMMA)  and chloroform were acquired from Sigma‐Aldrich and used during fibre manufacture. All solvents and chemicals were of analytical grade and used as received.2.1.2Escherichia coli T4 bacteriophage (ATCC 11303‐TB4) was used as the model organism throughout these experiments. Freeze‐dried cultures were sourced from LGC Standards and cultured following manufacturers’ instructions. Stock cultures of E. coli ATCC 11303 were stored in a MicrobankTM at −20°C, while the bacteriophage was kept at 2°C. Antiviral activity was assessed against this microorganism as it is commonly available and safe to work with in Biosafety Level 2 laboratories.ATCC Medium 129 was prepared using sodium chloride, nutrient agar and nutrient broth sourced from Sigma‐Aldrich. Phosphate buffer saline was used in the antiviral studies and purchased from Sigma‐Aldrich.2.22.2.1Graphene oxide nanosheets were analysed using scanning electron microscopy , while graphene nanoplatelets were analysed using transmission electron microscopy . Graphene oxide nanosheets were sputter‐coated with gold  for 180 s prior to imaging, while graphene nanoplatelet suspensions were prepared and drop‐casted onto carbon grids before imaging. Average diameters were estimated by measuring the width of approximately 100 specimens using ImageJ software .2.2.2E. coli was prepared by incubating a single colony in sterile medium, and a plaque assay was performed to determine the virus concentration at 0, 3 and 24 hr.T4 bacteriophage suspensions containing 0.5, 1.0 and 2.0 w/v% of graphene nanoplatelets or graphene oxide nanosheets in PBS were incubated for up to 24 hr. An actively growing broth culture of 2.2.3PMMA fibres containing 2 wt% of either graphene nanoplatelets or graphene oxide nanosheets were manufactured using pressurized gyration as previously reported  exhibited viral reductions of 20.8 ± 1.6% and 22.4 ± 1.3% for graphene nanoplatelets and graphene oxide, respectively. Further increasing the loading to 4 wt % of graphene nanoplatelets or graphene oxide nanosheets resulted in viral reductions of 26.0 ± 1.7% and 28.9 ± 1.2%, respectively. Fibres containing 8 wt % graphene nanoplatelets or graphene oxide nanosheets displayed the strongest potencies with average viral reductions of 33.6 ± 0.9% and 38.7 ± 1.1%, respectively. These results indicate that the antiviral activity of the nanocomposite fibres is in fact concentration‐dependent. Increasing the loading increases the concentration of graphene‐based nanomaterials on the surface of the fibres. Therefore, more of the active agent is exposed for the virions to interact with. A study by Mori et al  showed aThough the antiviral properties of the graphene loaded fibres were less effective when compared to pure nanoparticles, incorporating them into a polymer broadens their applications and demonstrates how they can be translated into different applications. As the graphene nanomaterials are entrapped in the fibres and not free floating, viral deactivation through direct interaction is not plausible. Therefore, only the secondary mechanism of action, production of reactive oxygen species, is functioning (Matharu et al., 4In the present study, graphene nanoplatelets and graphene oxide nanosheets exhibited antiviral activity towards DNA viruses after 3 hr of exposure. The antiviral mechanism of both materials is attributed to physical and chemical interactions, with direct nanoparticle interaction being the predominant mode of action. Both graphene nanoplatelets and graphene oxide nanosheets showed comparable antiviral activity, suggesting the oxygen functional group is expendable in the antiviral mode of action.The graphene nanoplatelet and graphene oxide polymer fibres also showed antiviral activity. The fibres show much weaker antiviral activity than the pure nanomaterials, suggesting that direct physical interaction is important for antiviral activity.This study reports, for the first time, the antiviral activity of graphene nanoplatelets, graphene oxide and nanosheets and their resulting nanocomposite fibres with a proposal for a potential mechanism of action. As a result, nanocomposites with potent antiviral properties at low concentrations can be produced by exploiting multiple driving forces at nano‐biointerfaces due to functionalization. The data presented here shed light on antiviral development, thus helping push the industry further and alleviating the burden on global health.The authors declare no conflicts of interest. The funders had no role in the design of the study; collection, analyses or interpretation of data; manuscript writing; or decision to publish the results.R.K.M. conceptualized the study, contributed to methodology, involved in validation, performed formal analysis, involved in investigation, wrote the original draft, reviewed and edited the manuscript, visualized the data and involved in project administration. H.P. involved in investigation, provided resources, wrote the original draft, and reviewed and edited the manuscript. B.C. provided resources, wrote the original draft, and reviewed and edited the manuscript. L.C. provided resources, wrote the original draft, reviewed and edited the manuscript, and acquired funding. M.E. provided resources, wrote the original draft, reviewed and edited the manuscript, supervised the study, and acquired funding.


Graphene/hBN heterostructures are promising active materials for devices in the THz domain, such as emitters and photodetectors based on interband transitions. Their performance requires long carrier lifetimes. However, carrier recombination processes in graphene possess sub-picosecond characteristic times for large non-equilibrium carrier densities at high energy. An additional channel has been recently demonstrated in graphene/hBN heterostructures by emission of hBN hyperbolic phonon polaritons (HPhP) with picosecond decay time. Here, we report on carrier lifetimes in graphene/hBN Zener-Klein transistors of ~30 ps for photoexcited carriers at low density and energy, using mid-infrared photoconductivity measurements. We further demonstrate the switching of carrier lifetime from ~30 ps (attributed to interband Auger) down to a few picoseconds upon ignition of HPhP relaxation at finite bias and/or with infrared excitation power. Our study opens interesting perspectives to exploit graphene/hBN heterostructures for THz lasing and highly sensitive THz photodetection as well as for phonon polariton optics. Long carrier lifetimes are beneficial for graphene-based optoelectronics, but carrier recombination processes in graphene possess sub-picosecond characteristic times. Here, the authors report carrier lifetimes ~30 ps at low energy in graphene/hBN Zener-Klein transistors, attributed to interband Auger processes. Importantly, for applications they keep their valuable performance up to room temperature. Graphene/hBN heterostructures are very attractive for the development of interband semiconductor laser schemes at THz frequencies owing to the gap-less electronic band structure of graphene3 and the fine low-doping control. For the realization of a THz laser, carrier lifetimes of a few tens of picoseconds are needed to reach long-lived optical gain. In addition, sensitive THz photodetectors are achievable in graphene/hBN heterostructures owing to the high carrier mobility in encapsulated graphene and its broad absorption spectrum5. For a compromise between sensitivity and speed in such THz photoconductors, carrier lifetimes of a few tens of picoseconds are also required. More generally, the recombination dynamics of non-equilibrium carriers close to the Dirac point in the encapsulated graphene layer plays a crucial role in the performance of interband optoelectronic THz devices and recombination times of at least a few tens of picoseconds are often highly desirable8.Graphene/hBN heterostructures uniquely combine high-quality graphene owing to the use of encapsulating layers12. Mostly, femtosecond visible or near infrared pulses are used to generate hot non-equilibrium carriers of large density at high energies. After photoexcitation, the electron/hole populations are both redistributed (by energy-conserving intraband carrier–carrier scattering) and relaxed  within ∼50 fs. It results in two independent lower-energy broad electron and hole distributions, for which efficient interband Auger recombination processes leads to a single Fermi–Dirac distribution for conduction and valence populations within 100–200 fs. A subsequent cooling process occurs mediated by interband optical phonon emissions within 1–2 ps and by less efficient intraband acoustical phonon scattering13. Very recently, an additional recombination channel with picosecond decay time has been demonstrated in hBN encapsulated graphene relying on the coupling of hot carriers in graphene with hyperbolic phonon polaritons (HPhPs) in the hBN layers15. Few studies have used optical pump with energies lower than optical phonon energy and reported significant slowing of the carrier relaxation16. However, owing to the excitation of a large density of hot carriers, optical phonon emission remained the predominant relaxation channel17. In spite of intensive work, the investigation of recombination dynamic for carriers at low photon energy and fluence remains elusive in graphene, notably under dc bias control.The recombination dynamics of non-equilibrium carriers in graphene has been widely investigatedω = 117 meV) and set graphene at charge neutrality point (CNP) where transport is dominated by interband Zener tunneling19. This provides weak incident photon density and corresponds to a photon energy between the Fermi-level fluctuations  and the optical phonons of graphene and hBN (ℏΩ ≈ 170–200 meV). Focusing on this low-energy domain, we unveil on a strong photoconductive regime involving a remarkably long Auger recombination time (~30 ps) and a switching to a short HPhP emission time at a finite dc bias or mid-infrared optical power. It also allows to investigate the interplay between optical and electrical pumping.Here we use continuous mid-infrared laser excitation . The bottom hBN layer, of thickness 67 nm, limits electrostatic doping to the range ±0.15 × 1012 cm−2. The thickness of the Ni layer is set to 12 nm to be semi-transparent to mid-infrared light with a measured transmission of T = 10.9%. From low-bias resistance measurements at 4 K reported in Fig. 2/Vs, a residual carrier density of n0 = 4 × 1010 cm−2 ascribed to residual charge puddles due to disordered potential likely created by air gaps at the Ni–hBN interface, and a contact resistance Rc = 650 Ω. As discussed in Supplementary Note 20.We investigate a transistor Fig.  fabricatVDS (which follows VCNP = Const. + 0.56 VDS)19. The dark current, Idark, at the CNP and at 4 K follows a superlinear bias dependence  doping; to this end, we compensate for drain doping by a careful calibration of the gate voltage at the CNP as function of 2 laser of wavelength λ = 10.6 µm, i.e. photon energy of 117 meV), we investigated the photoresponse of the graphene/hBN transistor at energies below the in-plane optical phonon energy branch (170–200 meV) of both graphene and hBN. The laser spot diameter is focused on the device with a waist of 21.2 µm quasi-matching the sample length. Figure 22. By contrast, the photocurrent at finite source-drain bias is symmetric with a maximum at the sample center. It has the same polarity as the dark current and its maximum value is seven times larger than the maxima in the unbiased condition. The spatial profile of the photocurrent is well described by the convolution of a constant photoresponse along the channel with the Gaussian profile of the laser beam . As a result, the photoconductive effect, where photoexcited electrons and holes are accelerated in opposite directions by an electric field, dominates over alternative photocurrent mechanisms at the CNP and at finite source-drain bias. As mentioned above, the photocurrent that relies on photoconductive effect is strongly sensitive to electrostatic doping. This is illustrated in Fig. 25, these were in a regime of high-photon energy (>0.7 eV).Let us discuss the competing mechanisms responsible for this photocurrent at finite source-drain bias in grapheneIn the following, we investigate successively three relevant photoconductive regimes: (i) the linear regime where both bias and optical power are low, (ii) the non-linear regimes where either power or bias exceed the linear photoconductive limit, and finally (iii) the full photoconductive response including all regimes.23. The photocurrent reaches the µA range. From these measurements and electrical characterization, we extract the photoexcited carrier density JPC = µ = 3.2 m2/V/s and 9 to ~0.7 × 109 cm−2. Note that the photoinduced electron and hole densities given by 7 cm−2) in ideal intrinsic graphene at T = 4 K. However, it remains relatively weak compared to the residual carrier density. To attain insight into the efficiency of the recombination processes, we can estimate the photoexcited carrier recombination time from the photocarrier densities and light excitation conditions23. The carrier diffusion is disregarded since the illumination and electric field are nearly uniform and the diffusion time is in the nanosecond range, i.e. much longer than recombination times. From a rate-equation approach, it follows that the total number of photoexcited carriers, with average density α0 is the light absorption, Slaser the area of the laser spot, ℏω is the photon energy, τ is a phenomenological carrier lifetime, M is a carrier multiplication factor  and Po the laser power incident on the sample. Po is lower than the incident optical power Pinc by a factor 0.63 due the larger size of the optical Gaussian beam with respect to the sample dimension. The light absorption α0 by the graphene layer is calculated using the transfer matrix method considering the layered geometry of our device (the hBN dielectric film of ~67 nm thickness and the Ni back gate of 12 nm thickness). We calculate the ratio of the electric fields at the graphene plane Et and of the incident light E0 (see Supplementary Note α0 = A(Et/E0)2 = 0.11% where A = 2.3% is the interband absorption in free space of monolayer graphene (in the absence of Pauli blocking at the CNP). We verify that the transmitted light through the device and the semi-transparent Ni electrode is proportional to the incident optical power, indicating no absorption saturation effect. In our experimental conditions, M is predicted to be close to unity. Indeed Jago et al. have calculated that M is typically <1.2 when photocarriers, with initial energy of 0.65 eV, evolve in a dc electric field27. Moreover, Tomadin et al. have predicted that M tends to unity when pump photon energy is lowered below 0.5 eV in undoped graphene sample28. Figure M = 1). We report on an unprecedented carrier lifetime of >30 ps  is expected to be the remaining scattering mechanism involved in the recombination of non-equilibrium carriers (i.e. photoinduced carriers in excess to the dark ones) in hBN/graphene/hBN transistors  with eV0 ~ (ℏΩII – ℏω) ≈ 54–84 meV. We therefore attribute the additional recombination channel to the emission of HPhPs in hBN layer41, consistent with previous works on similar hBN-encapsulated graphene where picosecond HPhP cooling times were reported42. In particular, a similar threshold was observed in noise thermometric experiments using samples of similar mobility19. Indeed, h-BN supports large number of propagating HPhP modes  that can be very efficiently coupled to the carriers in graphene via near-field coupling (i.e. super-Planckian coupling)41. These previous works have also demonstrated that recombination of electron–hole pairs in graphene through the direct coupling with intrinsic optical phonon in graphene (of comparable energy ħΩOP = 170–200 meV) plays a minor role in hBN/graphene heterostructures. This is because non-polar optical phonons are coupled to electrons via the deformation potential, giving rise to a smaller relaxation rate.We now turn to non-linear regimes to further explore the hBN/graphene heterostructure-based devices. At low-incident optical power, we observe in Fig. Γ, dominating over impurity scattering rate (τ < 0.3 ps deduced from the mobility). In graphene, carrier–carrier scattering is prominently collinear (due to momentum/energy conservation), meaning that it preserves momentum direction with respect to electric field orientation. Considering that Fermi velocity is energy independent in single layer graphene, the effect of electric field in carrier acceleration is independent of energy relaxation and therefore reminiscent of a ballistic case. In this picture, the electric field (bias) dependence maps the photocarrier energy distribution with respect to the HPhP energy. Figure eV0 = ℏΩ − ℏω < 0.1 eV. The bias dependence thus provides an energy spectroscopy of the local carrier energy distribution.Figure Δnphoto coupled to the HPhP, which falls in the range of 109 cm−2 for Popt = 1 mW, and the corresponding power drained away by HPhP emission given by PHPhP = ΔnphotoℏωHPhP/τ, which scales with the µW level.As discussed in Supplementary Note Psat ≈ 15 mW, independent of the graphene bias, corresponding to an absorbed optical power of 10 μW. To explain this non-linearity, let us consider that under large illumination, intraband carrier–carrier interactions (with ultrashort relaxation times of ∼20 fs) become more efficient, leading to a broadening of the hot carrier distribution within the electron and valence bands. Some fraction of hot carriers gain energy, potentially exceeding ℏΩII, enabling some photoexcited electron–hole pairs to efficiently recombine in the hyperbolic optical phonon modes of the hBN layer. Consequently, we attribute the photocurrent saturation observed at high incident optical power to the enhancement of photoexcited carrier rates that efficiently recombine into HPhPs. As shown in Supplementary Note Δnphoto coupled to the HPhP  and Popt , respectively. We deduce V0 = 0.07 V, P0 = 0.5 mW, 1/Γ1 ≈ 35 ps, and a unique −1/Γ2 ≈ 0.7 ps for both fits. Remarkably, the two different determinations of the threshold, from the onset in Fig. Finally, we enlarge scope to the full photoconductive response including bi-non-linear effects. Figure Pabs. The linear regime appears as a red plateau; the non-linear regimes of Fig. Figure In conclusion, using mid-infrared photoconductivity measurements we have investigated recombination processes of carriers photoexcited at low density and energy in graphene/hBN Zener–Klein transistors. We have shown remarkable long carrier lifetime, ~30 ps, in quasi-intrinsic graphene, ultimately limited by interband Auger processes. Long carrier lifetime in graphene/hBN heterostructures could have important implications for THz lasing and highly sensitive THz photodetection. We have also unveiled the possibility to switch on at finite dc bias or mid-infrared optical power the very efficient electron–hyperbolic phonon recombination channel. This allows the carrier lifetime control, which falls below a few picoseconds upon ignition of HPhP relaxation. Investigating recombination processes for non-equilibrium carriers at low density and energy in alternative materials such as bilayer graphene and topological insulators could provide unique basic physic knowledge. Furthermore, we have investigated the interplay between optical and electrical pumping and demonstrated the opto-electrical pumping of HPhPs in the hBN layer at high Joule power and high optical power. These works could promote graphene/hBN heterostructures as a platform for phonon polariton optics and nanoscale thermal management.2/Si substrates. We identified monolayer graphene sample by optical contrast and Raman spectroscopy, and clean hBN flakes were chosen after bright- and dark-field optical microscopy. Afterwards, we composed the hBN/graphene/hBN van der Waals heterostructures using a hot pick-up technique and we transferred the sandwich on the top of a 12-nm-thick Ni electrode. We localized the encapsulated graphene using Raman spectroscopy and we measured the hBN thickness and roughness using atomic force microscopy. After the sample characterization, we performed e-beam lithography on the heterostructure in order to define the design of the device (W × L = 10.4 µm × 20 µm) on the cleanest region of the sandwich and to obtain an HSQ resist mask. This mask was used to etch (Reactive Ion Etching) the top hBN layer in order to connect the graphene with one-dimensional edge contacts43. The last step of the device fabrication was the e-beam lithography to design the source, drain, and gate electrodes and metal evaporation (Cr-Au).The monolayer graphene and hexagonal BN flakes were produced by micro-mechanical exfoliation of bulk crystals on SiO2 laser delivering 10.6 µm wavelength light modulated at 5 kHz. The laser light is focused on the sample using an aspheric Ge lens. The sample is placed within a liquid He cryostat with ZnSe optical window. The photocurrent signal is measured with a lock-in amplifier. A photovoltaic multiple junction detector is used to measure the mid-infrared light transmitted through the hBN/graphene heterostructure-based device.The experiment is based on a COSupplementary Information


Urogenital sarcoidosis is very rare. PubMed search for “testicular sarcoidosis” returned only 26 articles. It usually affects the epididymis, followed by testis and vas deferens. It typically occurs in young adults. Symptoms are usually asymptomatic unilateral or bilateral scrotal swelling, testicular pain. Testicular sarcoidosis could be diagnosed in patients whose chief complaint is infertility. In the article by Kimura The differential diagnosis of urogenital sarcoidosis includes testicular tuberculosis, malignant lymphoma and testicular tumor.Diagnosis routine usually involves ultrasound examination of scrotum. Gallium‐67 scintigraphy also can be done. Sonographic examination of the scrotum usually reveals multifocal well‐defined, round, hypoechoic intratesticular lesions.The association between infertility and sarcoidosis is unknown. There are several reports on azoospermia and oligozoospermia in patients with sarcoidosis. Several causative explanations are possible. First is replacement of testicular tissue with granulomas. Another is sarcoidosis of epididymis resulting in obstructive azoospermia. Local effect of granuloma on spermatogenesis or systemic manifestation of sarcoidosis as secondary hypogonadism might also happen. Steroid treatment alleviating symptoms of sarcoidosis usually result in improvements in sperm count.Chronic sarcoidosis tends to relapse. Thus, exacerbation of symptoms in patients with testicular sarcoidosis could happen after remission period.The author declares no conflict of interest.