Observation of Strong Anisotropic Interlayer Excitons.

Anisotropic interlayer excitons had been theoretically predicted to exist in two-dimensional (2D) anisotropy/isotropy van der Waals heterojunctions. However, experimental results consolidating the theoretical prediction and exploring the related anisotropic optoelectronic response have not been reported so far. Herein, strong photoluminescence (PL) of anisotropic interlayer excitons is observed in a symmetric anisotropy/isotropy/anisotropy heterojunction exemplified by 3L-ReS2/1L-MoS2/3L-ReS2 using monolayer (1L) MoS2 and trilayer (3L) ReS2 as components. Sharp interlayer exciton PL peaks centered at ∼1.64, ∼1.61, and ∼1.57 eV are only observed at low temperatures of ≤120 K and become more pronounced as the temperature decreases. These interlayer excitons exhibit strong anisotropic PL intensity variations with periodicities of 180° as functions of the incident laser polarization angles. The polarization ratios of these interlayer excitons are calculated to be 1.33-1.45. Our study gives new insight into the manipulation of excitons in 2D materials and paves a new way for a rational design of novel anisotropic optoelectronic devices.

Association of per- and polyfluoroalkyl substances with hepatic steatosis and metabolic dysfunction-associated fatty liver disease among patients with acute coronary syndrome.

Etiology of hepatic steatosis and metabolic dysfunction-associated fatty liver disease (MAFLD) among acute coronary syndrome (ACS) remains unclear. Existing studies suggested the potential role of per- and polyfluoroalkyl substances (PFAS) in comorbidity of hepatic steatosis among ACS patients. Therefore, we conducted a cross-sectional study based on the ACS inpatients to assess the associations of plasma PFAS congeners and mixtures with hepatic steatosis and MAFLD. This study included 546 newly diagnosed ACS patients. Twelve PFAS were quantified using ultra-high-performance liquid chromatography-tandem mass spectrometry. Hepatic steatosis was defined by hepatic steatosis index (HSI). MAFLD was defined as the combination of hepatic steatosis based on the risk factor calculation with metabolic abnormalities. Generalized linear model was used to examine the associations of PFAS congeners with HSI and MAFLD. Adaptive elastic net (AENET) was further used for PFAS congeners selection. Mixture effects were also assessed with Bayesian kernel machine regression model (BKMR). Congeners analysis observed significant greater percent change of HSI for each doubling in PFOS (1.82%, 95% CI: 0.87%, 2.77%), PFHxS (1.17%, 95% CI: 0.46%, 1.89%) and total PFAS (1.84%, 95% CI: 0.56%, 3.14%). Moreover, each doubling in PFOS (OR=1.42, 95% CI: 1.13, 1.81), PFHxS (OR=1.31, 95% CI: 1.09, 1.59) and total PFAS (OR=1.43, 95% CI: 1.06, 1.94) was associated with increased risk of MAFLD. In AENET regression, only PFOS presented significant positive associations with HSI. Mixture analysis indicated significant positive associations between PFAS mixtures and HSI. This is the first study to demonstrate associations of PFAS congeners and mixtures with hepatic steatosis and MAFLD among ACS patients, which provides hypothesis into the mechanisms behind comorbidity of hepatic steatosis among ACS patients, as well as tertiary prevention of ACS.

Regioselective Tip-Enhanced Raman Spectroscopy of Lipid Membranes with Sub-Nanometer Axial Resolution.

Noninvasive and label-free analysis of cell membranes at the nanoscale is essential to comprehend vital cellular processes. However, conventional analytical tools generally fail to meet this challenge due to the lack of required sensitivity and/or spatial resolution. Herein, we demonstrate that tip-enhanced Raman spectroscopy (TERS) is a powerful nanoanalytical tool to analyze dipalmitoylphosphatidylcholine (DPPC) bilayers and human cell membranes with submolecular resolution in the vertical direction. Unlike the far-field Raman measurements, TERS spectra of the DPPC bilayers reproducibly exhibited a uniquely shaped C-H band. These unique spectral features were also reproducibly observed in the TERS spectrum of human pancreatic cancer cells. Spectral deconvolution and DFT simulations confirmed that the TERS signal primarily originated from vibrations of the CH3 groups in the choline headgroup of the lipids. The reproducible TERS results obtained in this study unequivocally demonstrate the ultrahigh sensitivity of TERS for nanoanalysis of lipid membranes under ambient conditions.

Association of metabolic dysfunction-associated fatty liver disease, type 2 diabetes mellitus, and metabolic goal achievement with risk of chronic kidney disease.

Background: Although type 2 diabetes mellitus (T2DM) plays a significant role in the association between metabolic dysfunction-associated fatty liver disease (MAFLD) and chronic kidney disease (CKD), how T2DM development and glycemic deterioration affect CKD and its renal function indicators, estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR), remains unknown. We aimed to assess the association between MAFLD, along with T2DM, and risk of CKD, and then evaluate the effect of metabolic goal achievement in MAFLD on the risk of CKD. Methods: In this cross-sectional study, 5,594 participants were included. Multivariate logistic regression and linear regression were used to examine the association between MAFLD with its T2DM status and metabolic goal achievement and risk of CKD, as well as eGFR and UACR. Results: The MAFLD group had a higher prevalence of CKD (16.2 vs. 7.6%, P < 0.001) than the non-MAFLD group. MAFLD was independently associated with an increased risk of CKD (odds ratio [OR]: 1.35, 95% CI: 1.09-1.67) and increased eGFR and UACR. Among the three MAFLD subtypes, only the T2DM subtype exhibited significant associations with increased risk of CKD (OR: 2.85, 95% CI: 2.24-3.63), as well as increased eGFR and UACR. Glycemic deterioration in MAFLD was dose-dependently associated with an increased risk of CKD (P-trend < 0.001). Achieved metabolic goals in MAFLD decreased the risk of CKD, eGFR, and UACR; MAFLD with 2 or 3 achieved metabolic goals was not significantly associated with the risk of CKD (OR: 0.81, 95% CI: 0.59-1.12) and albuminuria. Conclusion: MAFLD was independently associated with an increased risk of CKD, as well as increased eGFR and UACR. This association is strongly driven by T2DM status. Glycemic deterioration in MAFLD was dose-dependently associated with an increased risk of CKD. Achieved metabolic goals in MAFLD decreased the risk of CKD by reducing the risk of albuminuria.

Tip-enhanced nanoscopy of two-dimensional transition metal dichalcogenides: progress and perspectives.

The optoelectronic properties of two-dimensional (2D) transition metal dichalcogenide (TMD) thin layers prepared by exfoliation or chemical vapour deposition are strongly modulated by defects at the nanoscale. The mediated electronic and optical properties are expected to be spatially localised in a nanoscale width neighbouring the defects. Characterising such localised properties requires an analytical tool with nanoscale spatial resolution and high optical sensitivity. In recent years, tip-enhanced nanoscopy, represented by tip-enhanced Raman spectroscopy (TERS) and tip-enhanced photoluminescence (TEPL), has emerged as a powerful tool to characterise the localised phonon and exciton behaviours of 2D TMDs and heterojunctions (HJs) at the nanoscale. Herein, we first summarise the recent progress of TERS and TEPL in the characterisation of several typical defects in TMDs, such as edges, wrinkles, grain boundaries and other defects generated in transfer and growth processes. Then the local strain and its dynamic control of phonon and exciton behaviours characterised by TERS and TEPL will be reviewed. The recent progress in characterising TMD HJs using TERS and TEPL will be subsequently summarised. Finally, the progress of TERS and TEPL combined with optoelectronic sensitive electronic scanning probe microscopy (SPM) in the applications of TMDs will be reviewed.

A bibliometric analysis of graphene in acetaminophen detection: Current status, development, and future directions.

Acetaminophen is a widely used analgesic throughout the world. Detection of acetaminophen has particular value in pharmacy and clinics. Electrochemical sensors assembled with advanced materials are an effective method for the rapid detection of acetaminophen. Graphene-based carbon nanomaterials have been extensively investigated for potential analytical applications in the last decade. In this article, we selected papers containing both graphene and acetaminophen. Bibliometrics was used to analyze the relationships and trends among these papers. The results show that the topic has grown at a high rate since 2009. Among them, the detection of acetaminophen by an electrochemical sensor based on graphene is the most important direction. Graphene has moved from being a primary sensing material to a substrate for immobilization of other active ingredients. In addition, the degradation of acetaminophen using graphene-modified electrodes is also an important direction. We analyzed the research history and current status of this topic through bibliometrics. Authors, institutions, countries, and key literature were discussed. We also proposed perspectives for this topic.

MoS2/WSe2 vdW Heterostructures Decorated with PbS Quantum Dots for the Development of High-Performance Photovoltaic and Broadband Photodiodes.

van der Waals heterostructures (vdWHs) overcoming the lattice and processing limitations of conventional heterostructures provide an opportunity to develop high-performance 2D vdWH solar cells and photodiodes. However, it is challenging to improve the sensitivity and response speed of 2D vdWH photovoltaic devices due to the low light absorption efficiency and electron/hole traps in heterointerfaces. Here, we design a PbS/MoS2/WSe2 heterostructure photodiode in which a light-sensitive PbS quantum dot (QD) layer combined with a MoS2/WSe2 heterostructure significantly enhances the photovoltaic response. The electron current in the heterostructure is increased by the effective collection of photogenerated electrons induced by PbS QDs. The device exhibits a broadband photovoltaic response from 405 to 1064 nm with a maximum responsivity of 0.76 A/W and a specific detectivity of 5.15 × 1011 Jones. In particular, the response speed is not limited by multiple electron traps in the PbS QDs/2D material heterointerface, and a fast rising/decaying time of 43/48 µs and a -3 dB cutoff frequency of over 10 kHz are achieved. The negative differential capacitance and frequency dependence of capacitance demonstrate the presence of interface states in the MoS2/WSe2 heterointerface that hamper the improvement of the response speed. The scheme to enhance photovoltaic performance without sacrificing response speed provides opportunities for the development of high-performance 2D vdWH optoelectronic devices.

Visualizing Surface Phase Separation in PS-PMMA Polymer Blends at the Nanoscale.

Phase-separated polymer blend films are an important class of functional materials with numerous technological applications in solar cells, catalysis, and biotechnology. These technologies are underpinned by the precise control of phase separation at the nanometer length-scales, which is highly challenging to visualize using conventional analytical tools. Herein, we introduce tip-enhanced Raman spectroscopy (TERS), in combination with atomic force microscopy (AFM), confocal Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), as a sensitive nanoanalytical method to determine lateral and vertical phase-separation in polystyrene (PS)-poly(methyl methacrylate) (PMMA) polymer blend films. Correlative topographical, molecular, and elemental information reveals a vertical phase separation of the polymers within the top ca. 20 nm of the blend surface in addition to the lateral phase separation in the bulk. Furthermore, complementary TERS and XPS measurements reveal the presence of PMMA within 9.2 nm of the surface and PS at the subsurface of the polymer blend. This fundamental work establishes TERS as a powerful analytical tool for surface characterization of this important class of polymers at nanometer length scales.

Probing Nanoscale Exciton Funneling at Wrinkles of Twisted Bilayer MoS2 Using Tip-Enhanced Photoluminescence Microscopy.

In twisted bilayer (t2L) two-dimensional (2D) transition metal dichalcogenides, local strain at wrinkles strongly modulates the local exciton density and PL energy resulting in an exciton funneling effect. Probing such exciton behaviors especially at nanometer length scales is beyond the limit of conventional analytical tools due to the limited spatial resolution and low sensitivity. To address this challenge, herein we applied high-resolution tip-enhanced photoluminescence (TEPL) microscopy to investigate exciton funneling at a wrinkle in a t2L MoS2 sample with a small twist angle of 0.5°. Owing to a spatial resolution of <10 nm, excitonic behavior at nanoscale sized wrinkles could be visualized using TEPL imaging. Detailed investigation of nanoscale exciton funneling at the wrinkles revealed a deformation potential of -54 meV/%. The obtained results provide novel insights into the inhomogeneities of excitonic behaviors at nanoscale and would be helpful in facilitating the rational design of 2D material-based twistronic devices.

Electrochemical detection of Sudan red series azo dyes: Bibliometrics based analysis.

Sudan red azo dyes are banned from food because of their carcinogenic properties. It is necessary to establish a method for the detection of Sudan azo dyes in food. Among them, electrochemical sensing technology has become a very potential analytical method for food detection because of its fast, sensitive and low price. In this paper, we analyze the electrochemical detection of Sudan red azo dyes by bibliometric method. A total of 161 articles were analyzed from 2007 to 2021. The geographical and institutional distribution of these papers is used to understand the form of collaboration on this topic. Keyword analysis in these papers is used to understand the different directions in which the topic is studied at different stages. The results show that the topic reached its peak in 2015. The development of novel materials with excellent electrochemical activity has promoted the research on this topic. As detection limits continue to be lowered and sensors continue to be optimized, this topic currently does not continue to attract much attention.

Graphene-based electrochemical sensors for antibiotic detection in water, food and soil: A scientometric analysis in CiteSpace (2011-2021).

The residues of antibiotics in the environment pose a potential health hazard, so highly sensitive detection of antibiotics has always appealed to analytical chemists. With the widespread use of new low-dimensional materials, graphene-modified electrochemical sensors have emerged as an excellent candidate for highly sensitive detection of antibiotics. Graphene, its derivatives and its composites have been used in this field of exploration in the last decade. In this review, we have not only described the field using traditional summaries, but also used bibliometrics to quantify the development of the field. The literature between 2011 and 2021 was included in the analysis. Also, the sensing performance and detection targets of different sensors were compared. We were able to trace not only the flow of research themes, but also the future areas of development. Graphene is a material that has a high potential to be used on a large scale in the preparation of electrochemical sensors. How to design a sensor with selectivity and low cost is the key to bring this material from the laboratory to practical applications.

Polymer-buried van der Waals magnets for promising wearable room-temperature spintronics.

The demand for high-performance spintronic devices has boosted intense research on the manipulation of magnetism in van der Waals (vdW) magnets. Despite great efforts, robust ferromagnetic transitions above room temperature still face significant hurdles. Strain engineering can reversibly regulate magnetic exchange, but the degree of regulation is still impractical for most magnetic applications. Hereby we employ a large-strain transferrer to produce tunable strains of up to 4.7%, which induces authentic room-temperature ferromagnetism in large-area Fe3GeTe2 nanoflakes with 20-fold improvement in magnetization. The record increment of the Curie temperature (TC) of well above 400 K originates from the strain-enhanced magnetic anisotropy and excellent magnetoelastic coupling. The correlation between the emerging ferromagnetism and Raman spectral evolution is also established, which complements well the TC phase diagram in a large-strain region. In addition, an unusual exchange bias effect with a vertical magnetization shift is tracked for the first time upon bending, which reveals the hidden competition between antiferromagnetic and ferromagnetic coupling. The reversible strain manipulation of single-domain ferromagnetic order in a single nanoflake further opens up a route to develop low-power wearable spintronic devices. The findings here provide vast opportunities to exploit the possibility of practical applications of more vdW magnets.

Oligothiophene molecular wires at graphene-based molecular junctions.

The use of graphene as a new type of electrode at molecular junctions has led to a renewal of molecular electronics. Indeed, the symmetry breaking induced by the graphene electrode yields different electronic behaviors at the molecular junction and in particular enhanced conductance for longer molecules. In this respect, several studies involving different molecular backbones and anchoring groups have been performed. Here in the same line, we consider oligopthiophene based hybrid gold-graphene junctions and we measure their electrical properties using the STM-I(s) method in order to determine their attenuation factor and the effect of specific anchoring groups. The results are supported by density functional theory (DFT) calculations, and exhibit a similar behavior to what is observed at alkane-based junctions.

Visualising structural modification of patterned graphene nanoribbons using tip-enhanced Raman spectroscopy.

Graphene nanoribbons (GNRs) fabricated using electron beam lithography are investigated using tip-enhanced Raman spectroscopy (TERS) with a spatial resolution of 5 nm under ambient conditions. High-resolution TERS imaging reveals a structurally modified 5-10 nm strip of disordered graphene at the edge of the GNRs. Furthermore, hyperspectral TERS imaging discovers the presence of nanoscale organic contaminants on the GNRs. These results pave the way for nanoscale chemical and structural characterisation of graphene-based devices using TERS.

Early sex determination of Ginkgo biloba based on the differences in the electrocatalytic performance of extracted peroxidase.

Ginkgo biloba is a dioecious plant. Male ginkgoes are mainly used in landscaping, while females are mainly used for fruit production. However, sex identification of ginkgo is a difficult task, especially at the seedling stage. In this work, we present for the first time the use of electrochemical techniques for the identification of ginkgo sex based on the differences in peroxides within male and female ginkgos. Graphene was used to concentrate peroxides in ginkgo extract, thereby improving electrochemical signal sensitivity. The electrochemical reduction of hydrogen peroxide catalyzed by peroxidase was used as a prob for sex determination in ginkgo. This electrochemical identification technique can be used not only for the analysis of adult ginkgo, but also successfully for the analysis of tissue culture seedlings and live seedlings. This electrochemical sensor has excellent discrimination ability due to the difference in peroxidase content in the leaves and petiole of ginkgo of different sexes. This electrochemical sensor allows for a rapid identification of the sex of ginkgo and has a very strong potential for field analysis.

Multimodal Nanoscopic Study of Atomic Diffusion and Related Localized Optoelectronic Response of WS2/MoS2 Lateral Heterojunctions.

The atomic diffusion in transition metal dichalcogenides (TMDs) van der Waals heterojunctions (HJs) strongly modifies their optoelectronic properties in the nanoscale. However, probing such localized properties challenges the spatial resolution and the sensitivity of a variety of analytic tools. Herein, a multimodal nanoscopy (based on tip enhanced Raman spectroscopy (TERS) and photoluminescence (TEPL)) combined with the Kelvin probe force microscopy (KPFM) method was used to probe such nanoscale localized optoelectronic properties induced by atomic diffusion. Chemical vapor deposition (CVD)-grown lateral bilayer (2L) WS2/MoS2 HJs were imaged with a spatial resolution better than 40 nm via TERS and TEPL mapping by using intrinsic Raman and photoluminescence (PL) peaks. The contact potential difference (CPD), capacitance, and PL variation in a nanoscale vicinity of the HJ interface can be correlated to the local stoichiometry variation determined by TERS. The diffusion coefficients of W and Mo were obtained to be ∼0.5 × 10-12 and ∼1 × 10-12 cm2/s, respectively, by using Fick's second law. The obtained results would be useful to further understand the localized optoelectronic response of the TMDs HJs.

Photoluminescence properties of cuprous phosphide prepared through phosphating copper with a native oxide layer.

Although cuprous phosphide (Cu3P) has been widely studied and applied in other fields, its photoluminescence (PL) properties are rarely investigated. Herein, we report that Cu3P can emit near-infrared light at 750 nm. We show that the annealing and the presence of cuprous oxide can enhance the PL emission. The mechanism of the PL enhancement is the improvement of crystal quality and the formation of a space charge region. Our results provide a reference for improving the PL properties of p-type semiconductors.

Development of an electrochemical biosensor for phylogenetic analysis of Amaryllidaceae based on the enhanced electrochemical fingerprint recorded from plant tissue.

A biosensor has been developed based on disposable screen-printed electrode for recording the electrochemical fingerprint of plant leaf tissue. A thin layer of polydopamine functionalized graphene sheets was coated on the plant tissue modified electrode for signal enhancement. The voltammetric data recorded under different buffer solutions can be derived as patterns for species identification. As the distribution of electrochemical active compounds in plants is controlled by genes, these fingerprints can reflect differences at the genetic level between species. Therefore, the electrochemical fingerprint of plant tissues can be used for phylogenetic research without qualitative analysis. 19 species of Amaryllidaceae including A. africanus, Clivia miniata, Clivia nobilis, Crinum firmifolium, Crinum latifolium, Crinum moorei, Curculiga gracilis, Cyrtanthus breviflorus, Habranthus robustus, Haemanthus albiflos, Haemathus multiflorus, Hippeastrum rutilum, Hymenocallis littoralis, Leucojum aestivum, Sprekelia formosissima, Tulbaghia violacea, Zephyranthes grandiflora, Zephyranthes macrosiphon and Zephyranthes minima have been selected deliberately. The dendrogram deduced from the electrochemical fingerprint was compared with the molecular phylogenetics. The results indicate the electrochemical fingerprint-based phylogenetic study is a persuasive methodology for plant phylogenetic analysis.

Interaction between PHB2 and Enterovirus A71 VP1 Induces Autophagy and Affects EV-A71 Infection.

Enterovirus A71 (EV-A71) is a major pathogen that causes severe and fatal cases of hand-foot-and-mouth disease (HFMD). HFMD caused by EV-A71 seriously endangers children's health. Although autophagy is an important antiviral defense mechanism, some viruses have evolved strategies to utilize autophagy to promote self-replication. EV-A71 can utilize autophagy vesicles as replication scaffolds, indicating that EV-A71 infection is closely related to its autophagy induction mechanism. VP1, a structural protein of EV-A71, has been reported to induce autophagy, but the underlying mechanism is still unclear. In this study, we found that the C-terminus (aa 251-297) of VP1 induces autophagy. Mass spectrometry analysis suggested that prohibitin 2 (PHB2) interacts with the C-terminus of the EV-A71 VP1 protein, and this was further verified by coimmunoprecipitation assays. After PHB2 knockdown, EV-A71 replication, viral particle release, and viral protein synthesis were reduced, and autophagy was inhibited. The results suggest that PHB2 interaction with VP1 is essential for induction of autophagy and the infectivity of EV-A71. Furthermore, we confirmed that EV-A71 induced complete autophagy that required autolysosomal acidification, thus affecting EV-A71 infection. In summary, this study revealed that the host protein PHB2 is involved in an autophagy mechanism during EV-A71 infection.

Electrochemical Sex Determination of Dioecious Plants Using Polydopamine-Functionalized Graphene Sheets.

The rapid identification of sex has potential uses involving dioecious commercial plants. In this work, we first propose a rapid electrochemical analysis method for plant sex determination using the signal difference generated by the electrochemically active substances in plant tissue. Polydopamine-functionalized graphene was wrapped around plant tissue. The introduction of polydopamine-functionalized graphene could solve the problem of the instability of plant tissue immobilization and enhance the electrochemical signals from plant tissue. Taxus × media, Dioscorea zingiberensis, and Dioscorea bulbifera were deliberately selected as dioecious plant models due to their pharmaceutical applications. The sex of the plant was not obvious after simply comparing the electrochemical voltammograms. Scatter patterns and 3D surface patterns were generated based on the voltammograms recorded after different solvent extractions. Sex determination was successfully achieved by pattern recognition.