Chemical methods for the production of graphenes

Ready-made chlorpyrifos sensor using an agarose-based gel electrolyte on a reduced graphene oxide/cellulose acetate-modified screen-printed carbon electrode

A ready-made electrochemical sensor has been developed as an innovative platform for detecting nonaqueous chlorpyrifos (CPF), a water-insoluble organophosphate pesticide. Despite its effectiveness, CPF is among the most frequently detected pesticides in food and water and poses severe health risks, including neurological disorders and acute poisoning. As a tool for potentially limiting the harm caused by CPF, this study introduces a CPF sensor designed for simplified sample preparation, enhanced safety, and rapid monitoring in environmental and agricultural samples. The sensor integrates an agarose-based gel electrolyte with a cellulose acetate/reduced graphene oxide-modified screen-printed carbon electrode. The gel electrolyte was prepared by dissolving agarose in a methanol-tetraethylammonium iodide solution and casting it onto the electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) confirmed excellent linearity (R2 > 0.999) over 0.05-8.00 mM and 0.10-2.00 mM, respectively, with LoDs of 0.166 mM (CV) and 34.3 μM (0.012 mg/kg, DPV). This allows reliable quantitative analysis and detection below CPF residue limits set by the U.S. EPA and Thai Agricultural Standards. The recoveries for the application of ready-made sensor in environmental and agricultural samples achieved recoveries of 89.8-106.6 % with %RSD below 5 %, demonstrating high feasibility for CPF detection. This sensor enables direct CPF detection in organic solvents without complex preparation or electrochemical expertise. Its agarose gel matrix enhances safety by immobilizing the electrolyte, minimizing leakage, and improving stability, making it suitable for portable use. This ready-made sensor provides a reliable, user-friendly solution for CPF monitoring in agriculture and food safety.

Bifunctional sheets reduce the microbe and endotoxin contamination of tissue-derived collagen

Tendon-derived type I collagen is an essential biomaterial for various biomedical devices due to its inherent bioactivity and favorable environment for cells. Correspondingly, microbial and endotoxin contamination can be easily introduced during the collagen extraction process, which is generally overlooked in fundamental scientific research, especially the endotoxin residue. Conventional approaches for mitigating endotoxin exhibit limited effectiveness when applied to biomacromolecule products because of viscosity, clogging, and diminished bioactivity. In this study, we developed a bifunctional sheet that can simultaneously reduce the microbe and endotoxin contamination in collagen solution by co-incubation and subsequent magnetic separation, avoiding the issues of blockage and bioactivity impairment. The bifunctional sheet was successfully fabricated by modifying the magnetic graphene oxide with histamine. Collagen products treated by sheets exhibited reduced microbial and endotoxin contamination while maintaining their bioactivity for encapsulated cell growth. Additionally, inflammatory stimulation of collagen was decreased in vitro and in vivo after treatment. This work may present a facile approach for diminishing microbe and endotoxin residues in collagen products in basic research, obviating the non-essential use of a sterile workshop and facilitating the development of tissue-derived collagen research.

Electrochemically Reduced Graphene Oxide Covalently Bound Sensor for Paracetamol Voltammetric Determination

Designing a highly sensitive and efficient functionalized electrode for precise drug analysis remains a significant challenge. In this work, an electrochemical sensor based on a glassy carbon electrode (GCE) modified with phenyl diazonium salts (ph) and electrochemically reduced graphene oxide (ERGO), labeled GCE/ph/ERGO, was developed for the detection of paracetamol (PAR) in pharmaceutical matrices using square wave voltammetry (SWV). The modified electrode was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Compared to the bare GCE, the GCE/ph/ERGO sensor demonstrated significantly improved conductivity and anodic current peak for PAR over two orders of magnitude higher, indicating a substantial enhancement in electrochemical performance. Under optimized conditions, the developed sensor exhibited a low detection limit of 18.2 nM and a quantification limit of 60.6 nM. Precision studies yielded relative standard deviations (RSDs) below 8%. The sensor demonstrated excellent selectivity in the presence of common pharmaceutical excipients and high accuracy in the analysis of generic pharmaceutical formulations, with results comparable to those obtained by the HPLC technique. These findings confirm the sensor's reliability, stability, robustness, and suitability for routine analysis of PAR in pharmaceutical samples.

Phase transitions and morphology control of Langmuir Blodget (LB) films of graphene oxide

HYPOTHESIS

Understanding the Langmuir film formation process of flexible and soft materials like graphene oxide (GO) is essential, as it shows different trends compared to the conventional surface pressure-area (π-A) and compressional modulus (ε) isotherms of hard materials. Additionally, the size distribution and mechanical properties of the GO are assumed to affect the distinctive Langmuir-Blodgett (LB) film morphologies, such as overlaps and wrinkles.

EXPERIMENT

To gain a deeper insights of phase transitions in GO LB films, we propose a novel analysis of elastic tensile modulus versus surface pressure (|ε|-π) isotherms. This approach involves applying adequate compression to the GO sheets to generate an elastic force, followed by measuring the |ε|-π isotherms during the film's expansion. Additionally, we compared the surface morphology of GO LB films deposited under identical conditions using various GO colloidal solutions, each containing sheets with different size distributions.

FINDING

Upon expanding the GO Langmuir film after sufficient compression, a rapid stress release is observed leading to a clear inflection in the |ε|-π isotherms, indicating a phase transition from solid to liquid. Therefore, this study provides comprehensive insights into the behavior of GO Langmuir films. Furthermore, we demonstrated that morphological features, such as wrinkles and overlaps in GO LB films, can be effectively controlled by adjusting the size distribution and mechanical properties of GO sheets in the colloidal solution.

Advances in Graphene-Transition Metal Selenides Hybrid Materials for High-Performance Supercapacitors: A Review

Supercapacitors have attracted significant attention as energy storage devices due to their high power density, rapid charge-discharge capability, and long cycle life. Their performance is primarily influenced by electrode materials, electrolytes, and operational voltage windows. Among these, the development of advanced electrode materials is crucial for enhancing energy density, specific capacitance, and cyclic stability. This review focuses on recent advancements in graphene-based hybrid materials, particularly their integration with transition metal selenides (TMSs) for supercapacitor applications. Combining graphene and its derivatives with TMSs, which possess multiple oxidation states and high theoretical capacitance, results in hybrids with superior electrochemical performance. Studies show that these materials achieve higher specific capacitance, energy density, and power density compared to graphene composites with carbides, nitrides, phosphides, and oxides. Key findings include synthesis strategies, structural modifications, and electrochemical properties of graphene-TMS hybrids. Notably, these hybrids have demonstrated specific capacitances exceeding 3105 F/g at 1 A/g, power densities up to 5597.77 W/kg, and energy densities reaching 126.3 Wh/kg, making them highly promising for next-generation supercapacitors. This review critically evaluates the current state-of-the-art, explores the synergistic effects between graphene and TMSs, such as improved charge transfer kinetics and structural stability, and identifies challenges and future directions in graphene-TMS hybrid supercapacitors.

Nanomaterials for targeted therapy of kidney diseases: Strategies and advances

The treatment and management of kidney diseases pose a significant global burden. Due to the presence of blood circulation barriers and glomerular filtration barriers, drug therapy for kidney diseases faces challenges such as poor renal targeting, short half-life, and severe systemic side effects, severely hindering therapeutic progress. Therefore, the research and development of kidney-targeted therapeutic agents is of great clinical significance. In recent years, the application of nanotechnology in the field of nephrology has shown potential for revolutionizing the diagnosis and treatment of kidney diseases. Carefully designed nanomaterials can exhibit optimal biological characteristics, influencing various aspects such as circulation, retention, targeting, and excretion. Rationally designing and modifying nanomaterials based on the anatomical structure and pathophysiological environment of the kidney to achieve highly specific kidney-targeted nanomaterials or nanodrug delivery systems is both feasible and promising. Based on the targeted therapy of kidney diseases, this review discusses the advantages and limitations of current nanomedicine in the targeted therapy of kidney diseases, and summarizes the application and challenges of current renal active/passive targeting strategies, in order to further promote the development of kidney-targeted nanomedicine through a preliminary summary of previous studies and future prospects.

Gold Nanoparticle Incorporated Graphene Oxide as a SERS Platform for Ultratrace Antibody Free Sensing of the Cancer Biomarker CEA

A simple, fast, low-cost, and efficient method is designed for the synthesis of graphene oxide (GO) (20 nm) from graphite using a strong oxidant Ce(IV). GO is further modified with gold nanoparticles (AuNPs) (5-8 nm) to generate a AuGO nanocomposite (25 nm). Raman spectral analyses confirm that the synthesized AuGO has a potential selective sensing ability for the cancer biomarker carcinoembryonic antigen (CEA) in serum. Sensing assays are also carried out in the presence of high concentrations of glucose, cholesterol, and insulin using this method, which become significantly elevated in conditions of different pathophysiological disorders. Ultratrace antibody free sensing of CEA in serum is achieved using surface-enhanced Raman spectroscopy with an amazing LOD of 12.5 fg/mL. The interaction between CEA and AuGO is further established using Raman, fluorescence, circular dichroism spectroscopy, and theoretical studies. The specificity of sensing is tested by checking the response in the presence of other cancer biomarkers, such as CA 19-9, CA 125, and PSA, which do not show any signal enhancement with AuGO in Raman spectroscopy.

Graphene-Based Impregnation into Polymeric Coating for Corrosion Resistance

This review explores the development and application of the impregnation of graphene-based materials into polymeric coatings to enhance corrosion resistance. Derivatives of graphene, such as graphene oxide (GO) and reduced graphene oxide (rGO), have been increasingly integrated into polymer matrices to enhance polymers' mechanical, thermal, and barrier properties. Various synthesis approaches, viz., electrochemical deposition, chemical reduction, and the incorporation of functionalised graphene derivatives, have been explored for improving the dispersion and stability of graphene within polymers. These graphene-impregnated coatings have shown promising results in improving corrosion resistance by enhancing impermeability to corrosive agents and reinforcing mechanical strength under corrosive conditions. While the addition of graphene notably enhances coating performance, challenges remain in achieving uniform graphene dispersion and addressing the trade-offs between thickness and flexibility. This review highlights current advancements, limitations, and future directions, with a particular emphasis on optimising the synthesis techniques to maximise corrosion resistance while maintaining coating durability and economic feasibility.

Graphene and its modifications for enhanced adhesion in dental restoratives: a molecular docking and dynamics study

Graphene has attracted significant attention in dentistry due to its structural and adhesive properties, enhancing the mechanical performance of dental composites. This study investigates the behavior and interaction of monomers and graphene-based adhesives using molecular docking and molecular dynamics (MD) simulations. Binding energies and interactions between monomers and graphene derivatives were assessed using molecular docking, while MD simulations with the Forcite module and COMPASS II force field provided insights into the mechanical properties of the composites. The simulations involved energy minimization, NVT/NPT ensembles, and equilibration for 50 ns. The binding energies of the monomer-graphene complexes ranged from - 16.27 to -18.55 kcal/mol, with the Bis-GMA-Graphene Quantum Dot complex showing the most stable interaction. Mechanical properties such as Young's modulus, shear modulus, and flexural strength were calculated for selected complexes: Bis-GMA-Graphene Quantum Dot (14.74 GPa, 9.32 GPa, 120.51 MPa), EBPADMA-Graphene Quantum Dot (14.28 GPa, 9.13 GPa, 118.22 MPa), HEMA-Nitrogen-doped Graphene (9.85 GPa, 6.86 GPa, 95.7 MPa), TEGDMA-Graphene Oxide (11.96 GPa, 8.12 GPa, 110.23 MPa), and UDMA-CCOOH Functionalized Graphene (13.82 GPa, 8.43 GPa, 115.4 MPa). The Bis-GMA-Graphene Quantum Dot complex showed the highest stability with 20 hydrogen bonds. These results highlight graphene quantum dots and functionalized graphene derivatives as promising candidates for high-performance dental composites, offering strong adhesive properties and improved mechanical strength. Future research may focus on further optimizing these interactions and exploring additional graphene modifications.

Photo-induced degradation of toxic recalcitrant compounds from surface water: Insights into advanced nanomaterials, hybrid photocatalytic systems, and real applications

The rapid increase in toxic recalcitrant organic compounds (ROCs) from various industrial, residential, and agricultural sources poses a significant public health concern and threatens environmental preservation. The presence of these toxic ROCs weakens the effectiveness of conventional water and wastewater treatment systems. As a result, numerous physicochemical and biological treatment processes have been explored, each demonstrating varying removal efficiencies depending on experimental conditions. Given the limitations of existing treatment methods, research has increasingly focused on advanced oxidation processes, particularly photocatalysis. Photocatalysis is a prominent treatment technique due to its low sludge production, non-toxic nature, reusable characteristics, and ability to harness visible light. This review comprehensively examines the ecotoxicological effects of ROCs, existing biological and physicochemical treatment methods, advancements in photocatalyst synthesis, the transition from conventional to advanced photocatalysts, and hybrid treatment systems. In the context of photocatalytic removal of ROCs, the review also addresses several influencing parameters, including initial pollutant concentration, solution pH, light intensity, catalyst dose, and catalyst type. Global case studies focusing on the mechanisms of photocatalytic degradation of ROCs are highlighted. The documented photocatalysts for removing ROCs from water and wastewater have shown promising results. Moreover, integrating photocatalysis with advanced physicochemical and biological processes has effectively removed various dissolved (e.g., ROCs) and suspended impurities, showcasing its practical applications. Thus, this study could serve as a valuable resource for researchers and engineers working on the treatment of various micropollutants, such as ROCs, in real wastewater.

Advances in graphene-based nanomaterials for heavy metal removal from water: Mini review

The environment and public health are seriously at risk from the increasing levels of heavy metal (HM) pollution in water bodies, hence efficient remediation techniques must be developed. Unique physicochemical properties of graphene (Gn) such as its enormous surface area, chemical stability, and extraordinary adsorption capabilities have made it a promising candidate for application in various adsorption processes. Recent studies indicate the heavy metal removal capabilities of Gn-based materials such as Gn oxide (GO) and reduced GO (rGO) reach 99% efficiency rates for lead (Pb2+), cadmium (Cd2+), and mercury (Hg2+) through strong electrostatic bonds and metal coordination along with π-π stacking interactions. In addition, the selective nature of Gn-based adsorbents grows better through functionalization because it incorporates thiol, amine, and sulfonic acid groups. The integration of Gn-based materials with metal-organic frameworks (MOFs) combined with magnetic nanoparticles along with bio-based polymers enhances adsorption efficiency and increases stability while offering recyclability features. The conclusion of this study discusses the current obstacles such as cost, scalability, environmental impact, and selectivity and potential future developments for the widespread use of Gn-based adsorbents in water treatment, highlighting the significance of continued research to improve these substances for useful environmental applications. PRACTITIONER POINTS: Graphene-based materials exhibit high capacity for adsorbing various heavy metals, enhancing water purification. Functionalization of graphene improves its ability to selectively target and remove specific heavy metals like mercury and lead. Graphene derivatives can achieve heavy metal removal within minutes, making them efficient for water treatment. Despite high synthesis costs, graphene's superior performance may lower long-term operational costs in wastewater treatment.

Graphene Nanopore Fabrication and Applications

Graphene is a revolutionary material with excellent optical, electrical and mechanical properties and has garnered significant attention in the realm of nanopore technology. Devices incorporating graphene nanopores leverage the material's atomic thickness to enhance detection precision in solid-state nanopores. These nanopores exhibit high spatial resolution and ion selectivity, making them promising sensors for biomolecular detection. Additionally, their unique characteristics suggest their considerable potential for applications in material separation and osmotic power generation. In recent years, several literature reviews on graphene nanopores have been published; however, some have not fully addressed certain important aspects, such as the depth of theoretical analysis, the extent of coverage on technological advancements, and the exploration of potential applications. This paper reviews current fabrication methods, including "top-down" etching and "bottom-up" synthesis, highlighting their advantages and limitations. We also summarize diverse applications of graphene nanopores, such as in biomolecule detection and water desalination. Our findings emphasize the need for a deeper exploration of these aspects, advancing the field by showcasing the broader potential of graphene nanopores in addressing various technological challenges.

Nanocarbons Reinforcement Effect into Polyethylene Nanocomposites: γ-Ray Attenuation Potential and Hardness Improvement by the Taguchi Method

High-density polyethylene (HDPE) is a light and low-cost polymer widely explored as an excellent barrier material for γ-ray and neutron radiation in situations of high exposure (e.g., aerospace). Nevertheless, this polymer is not a suitable structural material due to its low mechanical resistance. Herein, amino-functionalized carbon nanotubes (CNTs) and graphene oxide (GO) were incorporated into HDPE and statistically studied through a Taguchi design of experiments (DoE) model that investigated their synergistic effect. After incorporating these nanocarbons, microscopy images suggest their homogeneous distribution into HDPE. Furthermore, X-ray diffraction shows that the HDPE crystallinity degree increased due to a nucleation effect caused by the nanofillers. Additionally, all nanocomposites presented improved microhardness resistance (up to 69%), particularly when both nanocarbons were incorporated into the matrix. The nanocomposite with higher microhardness resistance had the γ-ray attenuation potential, exhibiting a similar radiation shielding effect to HDPE, with a linear attenuation coefficient higher than Aluminum, a reference material. Hence, this study shows that the synergy between these nanocarbons can be explored to improve HDPE hardness without negatively affecting its attenuation ability. Therefore, these nanocomposites with improved hardness and γ-ray shielding are potential materials for applications requiring surface durability and radiation resistance, such as in air-/spacecraft systems.

Graphene-based nanomaterials applications for agricultural and food sector

In the past decade, graphene-based nanomaterials (GBNs) have been considerably investigated in agriculture due to their exceptionally enriched physicochemical properties. Productivity in the agricultural sector relies significantly on agrochemicals. However, conventional systems suffer from a lack of application efficiency, resulting in environmental pollution and associated problems. Due to high surface area, easy functionalization, high chemical stability, biocompatibility, and ability to adhere to biological structures, GBNs become a promising candidate for agro-delivery carriers. A comprehensive review on developments of GBNs for pesticide delivery, nutrient delivery, food packaging and preservation, and their impacts on plant growth and development are missing in the literature. To address this, here we presented a detailed review on the material design, agrochemicals loading, release or diffusion kinetics, in-vivo applications, and effects of GBNs on plants. The GBNs found to improve the efficacy of existing agrochemicals and food preservatives, aiming to decrease the overall burden of these substances. The incorporation of GBNs in biocompatible and biodegradable polymers is reported to improve their oxygen barrier and mechanical properties for food packaging applications, targeting to reduce the use of petroleum-derived polymers based current food packaging materials, which leads to serious environmental impacts. In the context of plant nanobionics, GBNs has been found to boost the plant growth at low concentrations. Here, recommendations for future research have been deliberated, drawing reference from the relevant area to gain a deeper understanding of the underlying science, and to develop better delivery and packaging applications approaches. Additionally, discussions on recommendations regarding the safe concentration of GBNs for plant nanobionics are presented to facilitate their secure and effective utilization.

Potential of Graphene-Functionalized Polymer Surfaces for Dental Applications: A Systematic review

Graphene, a two-dimensional carbon nanomaterial, has garnered widespread attention across various fields due to its outstanding properties. In dental implantology, researchers are exploring the use of graphene-functionalized polymer surfaces to enhance both the osseointegration process and the long-term success of dental implants. This review consolidates evidence from in-vivo and in-vitro studies, highlighting graphene's capacity to improve bone-to-implant contact, exhibit antibacterial properties, and enhance mechanical strength. This research investigates the effects of incorporating graphene derivatives into polymer materials on tissue response and compatibility. Among 123 search results, 14 articles meeting the predefined criteria were analyzed. The study primarily focuses on assessing the impact of GO and rGO on cellular function and stability in implants. Results indicate promising improvements in cellular function and stability with the use of GO-coated or composited implants. However, it is noted that interactions between Graphene derivatives and polymers may alter the inherent properties of the materials. Therefore, further rigorous research is deemed imperative to fully elucidate their potential in human applications. Such comprehensive understanding is essential for unlocking the extensive benefits associated with the utilization of Graphene derivatives in biomedical contexts.

Advancements in Cancer Treatment: Harnessing the Synergistic Potential of Graphene-Based Nanomaterials in Combination Therapy

Combination therapy, which involves using multiple therapeutic modalities simultaneously or sequentially, has become a cornerstone of modern cancer treatment. Graphene-based nanomaterials (GBNs) have emerged as versatile platforms for drug delivery, gene therapy, and photothermal therapy. These materials enable a synergistic approach, improving the efficacy of treatments while reducing side effects. This review explores the roles of graphene, graphene oxide (GO), and graphene quantum dots (GQDs) in combination therapies and highlights their potential to enhance immunotherapy and targeted cancer therapies. The large surface area and high drug-loading capacity of graphene facilitate the codelivery of multiple therapeutic agents, promoting targeted and sustained release. GQDs, with their unique optical properties, offer real-time imaging capabilities, adding another layer of precision to treatment. However, challenges such as biocompatibility, long-term toxicity, and scalability need to be addressed to ensure clinical safety. Preclinical studies show promising results for GBNs, suggesting their potential to revolutionize cancer treatment through innovative combination therapies.

Graphene/carbohydrate polymer composites as emerging hybrid materials in tumor therapy and diagnosis

Despite the introduction of various types of treatments for cancer control, cancer therapy faces several challenges such as aggressive behavior, heterogeneous characteristics, and the development of resistance. In contrast, the methods have depended on the creation and formulation of nanoparticles to impede tumor growth. Carbon nanoparticles have attracted considerable attention for cancer therapy, with graphene nanoparticles emerging as promising vehicles for delivering drugs and genes. Moreover, graphene composites can enhance immunotherapy, phototherapy, and combination therapies. Nonetheless, the biocompatibility and toxicity of graphene composites present difficulties. Consequently, this manuscript assesses the alteration of graphene nanocomposites using carbohydrate polymers. Altering graphene composites with carbohydrate polymers such as chitosan, hyaluronic acid, cellulose, and starch can enhance their efficacy in cancer treatment. Furthermore, graphene composites functionalized with carbohydrate polymers for tumor ablation induced by phototherapy. Graphene oxide and graphene quantum dots have been modified with carbohydrate polymers to enhance their therapeutic and diagnostic uses. These nanoparticles can transport gene therapy techniques like siRNA in the treatment of cancer. Despite the breakdown of these nanoparticles within the body, they maintain excellent biosafety and biocompatibility.

Atomistic Study on the Mechanical Properties of HOP-Graphene Under Variable Strain, Temperature, and Defect Conditions

HOP-graphene is a graphene structural derivative consisting of 5-, 6-, and 8-membered carbon rings with distinctive electrical properties. This paper presents a systematic investigation of the effects of varying sizes, strain rates, temperatures, and defects on the mechanical properties of HOP-graphene, utilizing molecular dynamics simulations. The results revealed that Young's modulus of HOP-graphene in the armchair direction is 21.5% higher than that in the zigzag direction, indicating that it exhibits greater rigidity in the former direction. The reliability of the tensile simulations was contingent upon the size and strain rate. An increase in temperature from 100 K to 900 K resulted in a decrease in Young's modulus by 7.8% and 2.9% for stretching along the armchair and zigzag directions, respectively. An increase in the concentration of introduced void defects from 0% to 3% resulted in a decrease in Young's modulus by 24.7% and 23.1% for stretching along the armchair and zigzag directions, respectively. An increase in the length of rectangular crack defects from 0 nm to 4 nm resulted in a decrease in Young's modulus for stretching along the armchair and zigzag directions by 6.7% and 5.7%, respectively. Similarly, an increase in the diameter of the circular hole defect from 0 nm to 4 nm resulted in a decrease in Young's modulus along both the armchair and zigzag directions, with a corresponding reduction of 11.0% and 10.4%, respectively. At the late stage of tensile fracture along the zigzag direction, HOP-graphene undergoes a transformation to an amorphous state under tensile stress. Our results might contribute to a more comprehensive understanding of the mechanical properties of HOP-graphene under different test conditions, helping to land it in potential practical applications.

Graphene Oxide and its Composites: Advanced Membranes for Selective Water Permeation

Graphene oxide (GO) membranes have gained significant attention as a promising material for separation by selective permeation processes due to their advantageous structural and chemical properties, including high water permeability, chemical resistance, and mechanical strength. In this study, we explore the potential applications of GO membranes in pervaporation to separate liquid mixtures. The layered structure and hydrophilic nature of GO membrane facilitate rapid and selective water transport through angstrom-scale interlayer spacings, resulting in superior performance over conventional polymeric and inorganic membranes. The unique mass transport mechanisms - slip flow and molecular alignment - enable GO membranes to selectively permeate water over organic solvents. For chemical dehydration, GO membranes are the most potential candidates. Furthermore, advancements in composite GO membranes and cross-linking techniques that improve their stability and separation performance are discussed. This study highlights the advantages of GO membranes and their potential to replace or complement existing technologies, by emphasizing their role in advancing membrane-based separation and promoting environmental sustainability. Future research is expected to optimize the fabrication techniques for GO membranes and expand their application scope.

Applicability of a green nanocomposite consists of reduced graphene oxide and β-cyclodextrin for electrochemical tracing of methadone in human biofluids validated by international greenness indexes

Background

Detecting methadone (MET) is crucial due to its severe side effects.

Method

Herein, a green nanocomposite based on reduced graphene (rGO) and β-cyclodextrin (β-CD) has been introduced to modify a glassy carbon electrode (GCE) for real-time measurement of MET. This eco-friendly sensing interface has synergistically benefited from both advantages of rGO and β-CD including excellent electron transfer tunneling and surface area enhancement to selectively trap MET based on its shape and size.

Significant findings

The developed sensor electrochemically detected MET at 0.8 V in buffer phosphate with a pH value of 7 under a wide linear concentration range (1 μM-830 μM), including a MET concentration level alarmed based on the consumer opioid tolerance according to the WHO's report. The limit of detection and analytical sensitivity values were calculated to be 333.33 nM and 0.0502 μA μM-1. The acceptable performance of the sensor to detect MET in various real human biofluids including serum, urine, and saliva samples, which is a bonus for the real-time and on-site measurement of MET, may open up a route for noninvasive routine tests in clinical samples. Moreover, the greenness profile of this strategy has been well evaluated by two common international metrics.

Exploring the landscape of FRET-based molecular sensors: Design strategies and recent advances in emerging applications

Probing biological processes in living organisms that could provide one-of-a-kind insights into real-time alterations of significant physiological parameters is a formidable task that calls for specialized analytic devices. Classical biochemical methods have significantly aided our understanding of the mechanisms that regulate essential biological processes. These methods, however, are typically insufficient for investigating transient molecular events since they focus primarily on the end outcome. Fluorescence resonance energy transfer (FRET) microscopy is a potent tool used for exploring non-invasively real-time dynamic interactions between proteins and a variety of biochemical signaling events using sensors that have been meticulously constructed. Due to their versatility, FRET-based sensors have enabled the rapid and standardized assessment of a large array of biological variables, facilitating both high-throughput research and precise subcellular measurements with exceptional temporal and spatial resolution. This review commences with a brief introduction to FRET theory and a discussion of the fluorescent molecules that can serve as tags in different sensing modalities for studies in chemical biology, followed by an outlining of the imaging techniques currently utilized to quantify FRET highlighting their strengths and shortcomings. The article also discusses the various donor-acceptor combinations that can be utilized to construct FRET scaffolds. Specifically, the review provides insights into the latest real-time bioimaging applications of FRET-based sensors and discusses the common architectures of such devices. There has also been discussion of FRET systems with multiplexing capabilities and multi-step FRET protocols for use in dual/multi-analyte detections. Future research directions in this exciting field are also mentioned, along with the obstacles and opportunities that lie ahead.

Density functional theory and molecular dynamics simulation of water molecules confined between two-dimensional graphene oxide surfaces

In this work, the interaction potentials of water molecule with the two-dimensional graphene oxide (GO) surfaces containing epoxy groups have been determined using the M06-2X/6-31g (d,p) level of theory at different orientations and separations and fitted to the Born-Huggins-Meyer (BHM) potential. Good agreements were found between the computed and the well-known OPLS-AA and Dreiding potentials. We have also used some calculated potentials and the well-known models in the molecular dynamics (MD) simulations. Our results showed that some of the calculated force fields for both 2D GO structures almost represent similar results of average number of hydrogen bonds (), radial distribution functions (RDF), self-diffusion coefficient, and angle distribution function (ADF) with the OPLS-AA and Dreiding models which are due to their agreements of the interaction potentials. However, some models in both GO systems represent different results because of their shifted potentials to the larger distances. Our results also showed that the confined water molecules tend to orient toward the epoxy groups on the GO surfaces and the distributions at the angles of θ = 0o (or θ = 180o) is more than the other distributions. The water molecules confined between the bent GO surfaces showed less diffusion coefficients than the flat structure.

Graphene oxide, starch, and kraft lignin bio-nanocomposite controlled-release phosphorus fertilizer: Effect on P management and maize growth

This study focuses on the synthesis and practical application of bio-nanocomposite films made from a mixture of starch (ST) and Kraft lignin (KL) with graphene oxide (GO) nanoparticles. FTIR, XRD, Raman, SEM, and TEM analysis confirmed the synthesis's success of GO. The bio-nanocomposites were used as advanced coatings for triple superphosphate (TSP) fertilizers, and their implications for maize (Zea mays L.) plant growth were examined. Incorporating GO into the composite matrix is a significant accomplishment of this study, as demonstrated by the noticeable changes observed in the FTIR spectra, indicating consequent structural changes. Morphological analyses conducted by SEM reveal changes in the surface characteristics of the ST/KL films, providing essential information about the structural details of the bio-nanocomposite. The utilization of precision-coated TSP fertilizers leads to a significant enhancement in mechanical strength, as demonstrated by the improved crush resistance. Furthermore, these formulations guarantee a gradual release of phosphorus, showcasing their potential for efficient nutrient management in agricultural settings. The study examines the practical application of coated TSP fertilizers in agriculture and their positive effects on various growth parameters of Maize (Zea mays L.) plants. Using these fertilizers promotes sustainable and efficient agricultural practices, contributing to developing innovative agrochemical solutions.

Graphene via Microwave Expansion of Graphite Followed by Cryo-Quenching and its Application in Electrostatic Droplet Switching

Monoelemental atomic sheets (Xenes) and other 2D materials offer record electronic mobility, high thermal conductivity, excellent Young's moduli, optical transparency, and flexural capability, revolutionizing ultrasensitive devices and enhancing performance. The ideal synthesis of these quantum materials should be facile, fast, scalable, reproducible, and green. Microwave expansion followed by cryoquenching (MECQ) leverages thermal stress in graphite to produce high-purity graphene within minutes. MECQ synthesis of graphene is reported at 640 and 800 W for 10 min, followed by liquid nitrogen quenching for 5 and 90 min of sonication. Microscopic and spectroscopic analyses confirmed the chemical identity and phase purity of monolayers and few-layered graphene sheets (200-12 µm). Higher microwave power yields thinner layers with enhanced purity. Molecular dynamics simulations and DFT calculations support the exfoliation under these conditions. Electrostatic droplet switching is demonstrated using MECQ-synthesized graphene, observing electrorolling of a mercury droplet on a BN/graphene interface at voltages above 20 V. This technique can inspire the synthesis of other 2D materials with high purity and enable new applications.

Laser-induced graphene gas sensors for environmental monitoring

Artemesia tridentata is a foundational plant taxon in western North America and an important medicinal plant threatened by climate change. Low-cost fabrication of sensors is critical for developing large-area sensor networks for understanding and monitoring a range of environmental conditions. However, the availability of materials and manufacturing processes is still in the early stages, limiting the capacity to develop cost-effective sensors at a large scale. In this study, we demonstrate the fabrication of low-cost flexible sensors using laser-induced graphene (LIG); a graphitic material synthesized using a 450-nm wavelength bench top laser patterned onto polyimide substrates. We demonstrate the effect of the intensity and focus of the incident beam on the morphology and electrical properties of the synthesized material. Raman analyses of the synthesized LIG show a defect-rich graphene with a crystallite size in the tens of nanometers. This shows that the high level of disorder within the LIG structure, along with the porous nature of the material provide a good surface for gas adsorption. The initial characterization of the material has shown an analyte response represented by a change in resistance of up to 5% in the presence of volatile organic compounds (VOCs) that are emitted and detected by Artemisia species. Bend testing up to 100 cycles provides evidence that these sensors will remain resilient when deployed across the landscapes to assess VOC signaling in plant communities. The versatile low-cost laser writing technique highlights the promise of low-cost and scalable fabrication of LIG sensors for gas sensor monitoring.

Advancing Albumin Isolation from Human Serum with Graphene Oxide and Derivatives: A Novel Approach for Clinical Applications

This study introduces a novel, environmentally friendly albumin isolation method using graphene oxide (GO). GO selectively extracts albumin from serum samples, leveraging the unique interactions between GO's oxygen-containing functional groups and serum proteins. This method achieves high purification efficiency without the need for hazardous chemicals. Comprehensive characterization of GO and reduced graphene oxide (rGO) through techniques such as X-ray diffraction (XRD) analysis, Raman spectroscopy, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) confirmed the structural and functional group transformations crucial for protein binding. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry analyses demonstrated over 95% purity of isolated albumin, with minimal contamination from other serum proteins. The developed method, optimized for pH and incubation conditions, showcases a green, cost-effective, and simple alternative for albumin purification, promising broad applicability in biomedical research and clinical applications.

Recent Research Progress of Porous Graphene and Applications in Molecular Sieve, Sensor, and Supercapacitor

Porous graphene, including 2D and 3D porous graphene, is widely researched recently. One of the most attractive features is the proper utilization of graphene defects, which combine the advantages of both graphene and porous materials, greatly enriching the applications of porous graphene in biology, chemistry, electronics, and other fields. In this review, the defects of graphene are first discussed to provide a comprehensive understanding of porous graphene. Then, the latest advancements in the preparation of 2D and 3D porous graphene are presented. The pros and cons of these preparation methods are discussed in detail, providing a direction for the fabrication of porous graphene. Moreover, various superior properties of porous graphene are described, laying the foundation for their promising applications. Owing to its abundant morphology, wide distribution of pore size, and remarkable properties benefited from porous structure, porous graphene can not only promote molecular diffusion and electron transfer but also expose more active sites. Consequently, a serious of applications containing gas sieving, liquid separation, sensors, and supercapacitors, are presented. Finally, the challenges confronted during preparation and characterization of porous graphene are discussed, offering guidance for the future development of porous graphene in fabrication, characterization, properties, and applications.

Revisiting oxidation and reduction reactions for synthesizing a three-dimensional hydrogel of reduced graphene oxide

An improvement to Hummers' method involving a cascade-design graphite oxidation reaction is reported to optimize safety and efficiency in the production of graphite oxide (GrO) and graphene oxide (GO). Chemical reduction using highly alkaline ammonia solution is a novel approach to synthesizing reduced graphene oxide (RGO). In this original research, we revisit the oxidation and reduction reactions, providing significant findings regarding the synthetic pathway to obtain a bioinspired water-intercalated hydrogel of RGO nanosheets. Influential factors in the graphite oxidation reaction, typically the exothermic reaction temperature and hydrogen peroxide effect, are described. Furthermore, the chemical reaction of GO reduction using highly alkaline ammonia solution (pH 14) was investigated to produce hydrated RGO nanosheets assembled in a hydrogel structure (97% water). Three-dimensional assembly and water intercalation are key to preserve the non-stacking state of RGO nanosheets. Therefore, ultrasound transmission to aqueous channels in the macroscopic RGO hydrogel vibrated and dispersed the RGO nanosheets in water. Analytical results revealed the single-layer nanostructures, functional groups, optical band gaps, optimized C/O ratios, particle sizes and zeta potentials of GO and RGO nanosheets. The reversible self-assembly of RGO hydrogels is essential for many applications, such as RGO coatings and polymer/RGO nanocomposites. In a water purification application, the RGO hydrogel was dispersed in aqueous solution by simple agitation and showed a high capacity for organic dye adsorption. After the adsorption, the RGO/dye particles were easily removed by filtration through ordinary cellulose paper. The process of adsorption and filtration is effective and inexpensive for practical environmental remediation. In summary, a bioinspired structure of RGO hydrogel is conceptualized for prospective nanotechnology.

Effects of size and shape of hole defects on mechanical properties of biphenylene: a molecular dynamics study

The distinctive multi-ring structure and remarkable electrical characteristics of biphenylene render it a material of considerable interest, notably for its prospective utilization as an anode material in lithium-ion batteries. However, understanding the mechanical traits of biphenylene is essential for its application, particularly due to the volumetric fluctuations resulting from lithium ion insertion and extraction during charging and discharging cycles. In this regard, this study investigates the performance of pristine biphenylene and materials embedded with various types of hole defects under uniaxial tension utilizing molecular dynamics simulations. Specifically, from the stress‒strain curves, we obtained key mechanical properties, including toughness, strength, Young's modulus and fracture strain. It was observed that various near-circular hole (including circular, square, hexagonal, and octagonal) defects result in remarkably similar properties. A more quantitative scaling analysis revealed that, in comparison with the exact shape of the defect, the area of the defect is more critical for determining the mechanical properties of biphenylene. Our finding might be beneficial to the defect engineering of two-dimensional materials.

High-precision Helicobacter pylori infection diagnosis using a dual-element multimodal gas sensor array

Helicobacter pylori (H. pylori) is a globally widespread bacterial infection. Early diagnosis of this infection is vital for public and individual health. Prevalent diagnosis methods like the isotope 13C or 14C labelled urea breath test (UBT) are not convenient and may do harm to the human body. The use of cross-response gas sensor arrays (GSAs) is an alternative way for label-free detection of metabolite changes in exhaled breath (EB). However, conventional GSAs are complex to prepare, lack reliability, and fail to discriminate subtle changes in EB due to the use of numerous sensing elements and single dimensional signal. This work presents a dual-element multimodal GSA empowered with multimodal sensing signals including conductance (G), capacitance (C), and dissipation factor (DF) to improve the ability for gas recognition and H. pylori-infection diagnosis. Sensitized by poly(diallyldimethylammonium chloride) (PDDA) and the metal-organic framework material NH2-UiO66, the dual-element graphene oxide (GO)-composite GSAs exhibited a high specific surface area and abundant adsorption sites, resulting in high sensitivity, repeatability, and fast response/recovery speed in all three signals. The multimodal sensing signals with rich sensing features allowed the GSA to detect various physicochemical properties of gas analytes, such as charge transfer and polarization ability, enhancing the sensing capabilities for gas discrimination. The dual-element GSA could differentiate different typical standard gases and non-dehumidified EB samples, demonstrating the advantages in EB analysis. In a case-control clinical study on 52 clinical EB samples, the diagnosis model based on the multimodal GSA achieved an accuracy of 94.1%, a sensitivity of 100%, and a specificity of 90.9% for diagnosing H. pylori infection, offering a promising strategy for developing an accurate, non-invasive and label-free method for disease diagnosis.

Ultrasensitive detection of 5-hydroxymethylcytosine in genomic DNA using a graphene-based sensor modified with biotin and gold nanoparticles

Ten-eleven translocation (TET) proteins orchestrate deoxyribonucleic acid (DNA) methylation-demethylation dynamics by oxidizing 5-methylcytosine to 5-hydroxymethylcytosine (5hmC) and are frequently inactivated in various cancers. Due to the significance of 5hmC as an epigenetic biomarker for cancer diagnosis, pathogenesis, and treatment, its rapid and precise quantification is essential. Here, we report a highly sensitive electrochemical method for quantifying genomic 5hmC using graphene sheets that were electrochemically exfoliated and functionalized with biotin and gold nanoparticles (Bt-AuNPs) through a single-step electrical method. The attachment of Bt-AuNPs to graphene enhances the specificity of 5hmC-containing DNA and augments the oxidation of 5hmC to 5-formylcytosine in DNA. When coupled to a gold electrode, the Bt-AuNP-graphene-based sensor exhibits exceptional sensitivity and specificity for detecting 5hmC, with a detection limit of 63.2 fM. Furthermore, our sensor exhibits a remarkable capacity to measure 5hmC levels across a range of biological samples, including preclinical mouse tissues with varying 5hmC levels due to either TET gene disruption or oncogenic transformation, as well as human prostate cancer cell lines. Therefore, our sensing strategy has substantial potential for cancer diagnostics and prognosis.

Graphene and its hybrid nanocomposite: A Metamorphoses elevation in the field of tissue engineering

In this discourse, we delve into the manifold applications of graphene-based nanomaterials (GBNs) in the realm of biomedicine. Graphene, characterized by its two-dimensional planar structure, superconductivity, mechanical robustness, chemical inertness, extensive surface area, and propitious biocompatibility, stands as an exemplary candidate for diverse biomedical utility. Graphene include various distinctive characteristics of its two-dimensional planar structure, enormous surface area, mechanical and chemical stability, high conductivity, and exceptional biocompatibility. We investigate graphene and its diverse derivatives, which include reduced graphene oxides (rGOs), graphene oxides (GOs), and graphene composites, with a focus on elucidating the unique attributes relevant to their biomedical utility. In this review article it highlighted the unique properties of graphene, synthesis methods of graphene and functionalization methods of graphene. In the quest for novel materials to advance regenerative medicine, researchers have increasingly turned their attention to graphene-based materials, which have emerged as a prominent innovation in recent years. Notably, it highlights their applications in the regeneration of various tissues, including nerves, skeletal muscle, bones, skin, cardiac tissue, cartilage, and adipose tissue, as well as their influence on induced pluripotent stem cells, marking significant breakthroughs in the field of regenerative medicine. Additionally, this review article explores future prospects in this evolving area of study.

Synergistic effect of Al2O3-decorated reduced graphene oxide on microstructure and mechanical properties of 6061 aluminium alloy

In this study, Al6061 alloy matrix composites reinforced Al2O3-decorated reduced graphene oxide (Al2O3/RGO) with 0.1, 0.3 and 0.5 weight present (wt%) were successfully fabricated using high energy ball milling and hot extrusion techniques. The microstructures of these Al2O3/RGO/Al6061 aluminum matrix composites (Al MMCs) were characterized. The results showed that Al2O3/RGO were uniformly distributed within the Al6061 matrix and tightly bonded to the matrix. Al2O3 encapsulation on RGO surface would prevent the formation of Al4C3 brittle phase in matrix, ensuring that there was no reaction between the reinforcement and the matrix Al6061. Tensile strength and Vickers hardness tests demonstrated that the mechanical properties of Al MMCs significantly increased with addition of Al2O3/RGOs. Remarkably, Al MMCs with 0.1 wt% reinforcement showed tensile yield and tensile strengths of 270 MPa and 286 MPa, respectively, which were 49% and 43% higher than those of pure Al6061 prepared using the same process. Furthermore, the 0.1 wt% Al2O3/RGO composite also showed the best plastic deformation capability in considering of the strength.

Effect of a solvothermal method using DMF on the dispersibility of rGO, application of rGO as a CDI electrode material, and recovery of sp2-hybridized carbon

Graphene is prized for its large surface area and superior electrical properties. Efforts to maximize the electrical conductivity of graphene commonly result in the recovery of sp2-hybridized carbon in the form of reduced graphene oxide (rGO). However, rGO shows poor dispersibility and aggregation when mixed with other materials without hydrophilic functional groups, This could lead to electrode delamination, agglomeration, and reduced efficiency. This study focuses on the impact of solvothermal reduction on the dispersibility and capacitance of rGO compared with chemical reduction. The results show that the dispersibility of rGO-D obtained through solvothermal reduction using N,N-dimethylformamide improved compared to that obtained through chemical reduction (rGO-H). Furthermore, when utilized as a material for CDI, an improvement in deionization efficiency was observed in the AC@rGO-D-based CDI system compared to AC@rGO-H and AC. However, the specific surface area, a key factor affecting CDI efficiency, was higher in rGO-H (249.572 m2 g-1) than in rGO-D (150.661 m2 g-1). While AC@rGO-H is expected to exhibit higher deionization efficiency due to its greater specific surface area, the opposite was observed. This highlights the effect of the improved dispersibility of rGO-D and underscores its potential as a valuable material for CDI applications.

Exploration of isoelectronic substitution in graphene dioxide for photocatalytic and photovoltaic applications - an ab-initio study

Herein, we propose graphene dioxide (GDO) derivatives as promising materials for green hydrogen production by photocatalytic water splitting. The optoelectronic and photocatalytic properties of GDO, an insulator with a wide band gap, are tuned by designing new compositions through isovalent substitution of S/Se at the O site, Si and (B,N) at the C site. The newly predicted GDO derivatives were studied using hybrid functional calculations and our results show that several of these materials exhibit semiconducting behavior with a direct band gap value higher than 1.23 eV, hence appropriate for visible light-driven photocatalytic water splitting. The structural stability of these materials was analyzed by total energy and lattice dynamical calculations. The photo generated charge carriers possess lower effective mass and hence higher carrier mobility resulting in suppressed recombination rate and hence improving the water splitting efficiency. Apart from low excitonic binding energy, the electronic structure analysis shows that in several of these compounds the electrons and holes reside in two different atomic sites ensuring further reduction in recombination rate. The relatively higher absorption coefficient of GDO derivatives in the visible part of the solar spectrum indicates enhanced photoconversion efficiency suitable for solar cell applications also and it was further determined by photovoltaic performance parameter analysis. The band edge potential of GDO derivatives is well straddled by the water redox potential at different pHs, suggesting their potential for water splitting along with the possibility of CO2 reduction. Our findings indicate that the newly predicted compositions hold significant promise for photocatalytic as well as photovoltaic applications.

Effect of strain on the photoelectric properties of molybdenum ditelluride under vacancy defects: a DFT investigation

CONTEXT

This study explores the impact of deformation on the electrical and optical characteristics of monolayer cadmium telluride (MoTe2) with vacancies, using the foundational principles of density functional theory. It was discovered that both strain and imperfections alter the electrical characteristics of monolayer MoTe2. Under VTe-MoTe2, a direct-to-indirect band-gap transition occurs. In DTe-MoTe2, the band-gap value reduces dramatically, the conduction band changes downward, and the carrier concentration rises. The DVTe-induced band gap state is closer to the Fermi energy level than the VTe-induced band gap state. In this paper, DTe-MoTe2 is chosen for tensile deformation. The results show that the band-gap value tends to decrease by increasing tensile deformation. When the stretching value reaches 10%, the lower bound of the conduction band and the top of the valence band overlap, and the system is converted from a semiconductor to a metal. Considering the density of states, the missing state MoTe2 is mainly contributed by the participation of Te-s, Te-p, and Mo-d orbitals. In terms of optical qualities, the absorption and reflection peaks are red-shifted and blue-shifted, respectively. It is hoped that these effects on the optoelectronic properties will be widely applied.

METHODS

In this study, we utilize the generalized gradient approximation plane-wave pseudopotential method, incorporating Perdew-Burke Ernzerhof (PBE) generalized functions and following the fundamental principles of the density functional theory framework. A 3 × 3 × 1 supercell was constructed as an undoped model based on a MoTe2 monolayer, which consists of 9 Mo atoms and 18 Te atoms. The vacuum flat plate was set to 15 Å along the z-direction to avoid interactions between the monolayers. For electronic structure calculations, the energy cutoff was set to 450 eV. Each model's computational process and structural optimization were carried out using the Monkhorst-Pack specialized K-point sampling approach. Crystal optimization computations used a 3 × 3 × 1 Monkhorst-Pack K-point grid for molybdenum ditelluride monolayers and a 9 × 9 × 1 K-point grid for electronic system analysis, analyzing state density and optical characteristics, respectively. For the structural optimization, the convergence requirements for maximum force, maximum atom displacement, maximum stress, and energy change were defined at 0.03 eV/Å, 0.001 Å, 0.05 Gpa, and 1.0 × 10-5 eV/atom, respectively.

Research Progress of Natural Rubber Wet Mixing Technology

The performance of natural rubber (NR), a naturally occurring and sustainable material, can be greatly enhanced by adding different fillers to the NR matrix. The homogeneous dispersion of fillers in the NR matrix is a key factor in their ability to reinforce. As a novel method, wet mixing technology may effectively provide good filler dispersion in the NR matrix while overcoming the drawbacks of conventional dry mixing. This study examines the literature on wet mixing fillers, such as graphene, carbon nanotubes, silica, carbon black, and others, to prepare natural rubber composites. It also focuses on the wet preparation techniques and key characteristics of these fillers. Furthermore, the mechanism of filler reinforcement is also examined. To give guidance for the future development of wet mixing technology, this study also highlights the shortcomings of the current system and the urgent need to address them.

Toward Humidity-Independent Sensitive and Fast Response Temperature Sensors Based on Reduced Graphene Oxide/Poly(vinyl alcohol) Nanocomposites

Flexible temperature sensors are becoming increasingly important these days. In this work, we explore graphene oxide (GO)/poly(vinyl alcohol) (PVA) nanocomposites for potential application in temperature sensors. The influence of the mixing ratio of both materials, the reduction temperature, and passivation on the sensing performance has been investigated. Various spectroscopic techniques revealed the composite structure and atomic composition. These were complemented by semiempirical quantum chemical calculations to investigate rGO and PVA interaction. Scanning electron and atomic force microscopy measurements were carried out to evaluate dispersion and coated film quality. The temperature sensitivity has been evaluated for several composite materials with different compositions in the range from 10 to 80 °C. The results show that a linear temperature behavior can be realized based on rGO/PVA composites with temperature coefficients of resistance (TCR) larger than 1.8% K-1 and a fast response time of 0.3 s with minimal hysteresis. Furthermore, humidity influence has been investigated in the range from 10% to 80%, and a minor effect is shown. Therefore, we can conclude that rGO/PVA composites have a high potential for excellent passivation-free, humidity-independent, sensitive, and fast response temperature sensors for various applications. The GO reduction is tunable, and PVA improves the rGO/PVA sensor performance by increasing the tunneling effect and band gap energy, consequently improving temperature sensitivity. Additionally, PVA exhibits minimal water absorption, reducing the humidity sensitivity. rGO/PVA maintains its temperature sensitivity during and after several mechanical deformations.

Composites of Titanium-Molybdenum Mixed Oxides and Non-Traditional Carbon Materials: Innovative Supports for Platinum Electrocatalysts for Polymer Electrolyte Membrane Fuel Cells

TiO2-based mixed oxide-carbon composite support for Pt electrocatalysts provides higher stability and CO tolerance under the working conditions of polymer electrolyte membrane fuel cells compared to traditional carbon supports. Non-traditional carbon materials like graphene nanoplatelets and graphite oxide used as the carbonaceous component of the composite can contribute to its affordability and/or functionality. Ti(1-x)MoxO2-C composites involving these carbon materials were prepared through a sol-gel route; the effect of the extension of the procedure through a solvothermal treatment step was assessed. Both supports and supported Pt catalysts were characterized by physicochemical methods. Electrochemical behavior of the catalysts in terms of stability, activity, and CO tolerance was studied. Solvothermal treatment decreased the fracture of graphite oxide plates and enhanced the formation of a reduced graphene oxide-like structure, resulting in an electrically more conductive and more stable catalyst. In parallel, solvothermal treatment enhanced the growth of mixed oxide crystallites, decreasing the chance of formation of Pt-oxide-carbon triple junctions, resulting in somewhat less CO tolerance. The electrocatalyst containing graphene nanoplatelets, along with good stability, has the highest activity in oxygen reduction reaction compared to the other composite-supported catalysts.

Lithium-Ion Dynamic and Storage of Atomically Precise Halogenated Nanographene Assemblies via Bottom-Up Chemical Synthesis

Graphene has received much scientific attention as an electrode material for lithium-ion batteries because of its extraordinary physical and electrical properties. However, the lack of structural control and restacking issues have hindered its application as carbon-based anode materials for next generation lithium-ion batteries. To improve its performance, several modification approaches such as edge-functionalization and electron-donating/withdrawing substitution have been considered as promising strategies. In addition, group 7A elements have been recognized as critical elements due to their electronegativity and electron-withdrawing character, which are able to further improve the electronic and structural properties of materials. Herein, we elucidated the chemistry of nanographenes with edge-substituted group 7A elements as lithium-ion battery anodes. The halogenated nanographenes were synthesized via bottom-up organic synthesis to ensure the structural control. Our study reveals that the presence of halogens on the edge of nanographenes not only tunes the structural and electronic properties but also impacts the material stability, reactivity, and Li+ storage capability. Further systematic spectroscopic studies indicate that the charge polarization caused by halogen atoms could regulate the Li+ transport, charge transfer energy, and charge storage behavior in nanographenes. Overall, this study provides a new molecular design for nanographene anodes aiming for next-generation lithium-ion batteries.

Sensitive and selective electrochemical aptasensing method for the voltammetric determination of dopamine based on AuNPs/PEDOT-ERGO nanocomposites

In this study, the effects of phosphate buffered saline (PBS) and graphene oxide (GO) as supporting electrolytes and dopants on the electropolymerization process of 3,4-ethylenedioxythiophene (EDOT) on glassy carbon electrode (GCE) were investigated. It was found that the PEDOT-ERGO nanocomposites obtained by a simple one-step electrochemical redox polymerization method using GO as the only supporting electrolyte and dopant possess excellent electrochemical properties. Then, the PEDOT-ERGO nanocomposites were used as electrode substrate to further modify with AuNPs, and an electrochemical aptasensor based on AuNPs/PEDOT-ERGO nanocomposites was successfully constructed for the sensitive and selective determination of dopamine (DA). Comparison of the cyclic voltammetric response of different neurotransmitters before and after aptamer assembly showed that the aptamer significantly improved the selectivity of the sensor for DA. The low detection limit of 1.0 μM (S/N = 3) indicated the good electrochemical performance of the PEDOT-ERGO nanocomposite film. Moreover, the aptasensor showed good recoveries in 50-fold diluted fetal bovine serum with RSD values all less than 5 % (n = 5), indicating that the PEDOT-ERGO nanocomposites and the electrochemical aptasensor have promising applications in other neurochemicals assay and biomedical analysis.

Facile Preparation of High-Performance Reduced Graphene Oxide (RGO)/Copper (Cu) Composites Based on Pyrolysis of Copper Formate

Graphene has attracted much interest in many scientific fields because of its high specific surface area, Young's modulus, fracture strength, carrier mobility and thermal conductivity. In particular, the graphene oxide (GO) prepared by chemical exfoliation of graphite has achieved low-cost and large-scale production and is one of the most promising for Cu matrix composites. Here, we prepared a high strength, high electrical conductivity and high thermal conductivity reduced graphene oxide (RGO)/Cu composite by directly heating the GO/copper formate. The oxygen-containing functional groups and defects of RGO are significantly reduced compared with those of GO. The tensile yield strength and thermal conductivity of RGO/Cu composite with RGO volume fraction of 0.49 vol.% are as high as 553 MPa and 364 W/(m·K) at room temperature, respectively. The theoretical value of the tensile yield strength of the composite is calculated according to the strengthening mechanism, and the result shows that it agrees with the experimental value. After hot-rolling treatment, the ductility and conductivity of the composite materials have been greatly improved, and the ductility of the RGO/Cu composite with RGO volume fraction of 0.49 vol.% has been increased to four times the original. This work provides a highly efficient way to fabricate a high-performance RGO-reinforced Cu composite for commercial application.

One-Pot Synthesis of Functionalised rGO/AgNPs Hybrids as Pigments for Highly Conductive Printing Inks

This work provides a method for the development of conductive water-based printing inks for gravure, flexography and screen-printing incorporating commercial resins that are already used in the printing industry. The development of the respective conductive materials/pigments is based on the simultaneous (in one step) reduction of silver salts and graphene oxide in the presence of 2,5-diaminobenzenesulfonic acid that is used for the first time as the common in-situ reducing agent for these two reactions. The presence of aminophenylsulfonic derivatives is essential for the reduction procedure and in parallel leads to the enrichment of the graphene surface with aminophenylsulfonic groups that provide a high hydrophilicity to the final materials/pigments.

Enhanced Mass Activity and Durability of Bimetallic Pt-Pd Nanoparticles on Sulfated-Zirconia-Doped Graphene Nanoplates for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cell Applications

Developing highly active and durable Pt-based electrocatalysts is crucial for polymer electrolyte membrane fuel cells. This study focuses on the performance of oxygen reduction reaction (ORR) electrocatalysts composed of Pt-Pd alloy nanoparticles on graphene nanoplates (GNPs) anchored with sulfated zirconia nanoparticles. The results of field emission scanning electron microscopy and transmission electron microscopy showed that Pt-Pd and S-ZrO2 are well dispersed on the surface of the GNPs. X-ray diffraction revealed that the S-ZrO2 and Pt-Pd alloy coexist in the Pt-Pd/S-ZrO2-GNP nanocomposites without affecting the crystalline lattice of Pt and the graphitic structure of the GNPs. To evaluate the electrochemical activity and reaction kinetics for ORR, we performed cyclic voltammetry, rotating disc electrode, and EIS experiments in acidic solutions at room temperature. The findings showed that Pt-Pd/S-ZrO2-GNPs exhibited a better ORR performance than the Pt-Pd catalyst on the unsulfated ZrO2-GNP support and with Pt on S-ZrO2-GNPs and commercial Pt/C.

Synthesis of rGO/CoFe2O4 Composite and Its Magnetorheological Characteristics

In this study, composite particles of rGO/CoFe2O4 were synthesized using a solvothermal method to fabricate a low-density magnetorheological (MR) material with enhanced sedimentation stability. The morphology and crystallographic features of rGO/CoFe2O4 were characterized via SEM, TEM, and XRD, and its magnetic properties were tested using VSM. The MR fluid was formulated by blending rGO/CoFe2O4 particles into silicone oil. Under different magnet strengths (H), a rotational rheometer was used to test its MR properties. Typical MR properties were observed, including shear stress, viscosity, storage/loss modulus, and dynamic yield stress (τdy) following the Herschel-Bulkley model reaching 200 Pa when H is 342 kA/m. Furthermore, the yield stress of the MR fluid follows a power law relation as H increases and the index changes from 2.0 (in the low H region) to 1.5 (in the high H region). Finally, its MR efficiency was calculated to be about 104% at H of 342 kA/m.

2D graphene-based advanced nanoarchitectonics for electrochemical biosensors: Applications in cancer biomarker detection

Low-cost, rapid, and easy-to-use biosensors for various cancer biomarkers are of utmost importance in detecting cancer biomarkers for early-stage metastasis control and efficient diagnosis. The molecular complexity of cancer biomarkers is overwhelming, thus, the repeatability and reproducibility of measurements by biosensors are critical factors. Electrochemical biosensors are attractive alternatives in cancer diagnosis due to their low cost, simple operation, and promising analytical figures of merit. Recently graphene-derived nanostructures have been used extensively for the fabrication of electrochemical biosensors because of their unique physicochemical properties, including the high electrical conductivity, adsorption capacity, low cost and ease of mass production, presence of oxygen-containing functional groups that facilitate the bioreceptor immobilization, increased flexibility and mechanical strength, low cellular toxicity. Indeed, these properties make them advantageous compared to other alternatives. However, some drawbacks must be overcome to extend their use, such as poor and uncontrollable deposition on the substrate due to the low dispersity of some graphene materials and irreproducibility of the results because of the differences in various batches of the produced graphene materials. This review has documented the most recently developed strategies for electrochemical sensor fabrication. It differs in the categorization method compared to published works to draw greater attention to the wide opportunities of graphene nanomaterials for biological applications. Limitations and future scopes are discussed to advance the integration of novel technologies such as artificial intelligence, the internet of medical things, and triboelectric nanogenerators to eventually increase efficacy and efficiency.

Influence of Defects and Charges on the Colloidal Stabilization of Graphene in Water

Mastering graphene preparation is an essential step to its integration into practical applications. For large-scale purposes, full graphite exfoliation appears as a suitable route for graphene production. However, it requires overpowering attractive van der Waals forces demanding large energy input, with the risk of introducing defects in the material. This difficulty can be overcome by using graphite intercalation compounds (GICs) as starting material. The greater inter-sheet separation in GICs (compared with graphite) allows the gentler exfoliation of soluble graphenide (reduced graphene) flakes. A solvent exchange strategy, accompanied by the oxidation of graphenide to graphene, can be implemented to produce stable aqueous graphene dispersions (Eau de graphene, EdG), which can be readily incorporated into many processes or materials. In this work, we prove that electrostatic forces are responsible for the stability of fully exfoliated graphene in water, and explore the influence of the oxidation and solvent exchange procedures on the quality and stability of EdG. We show that the amount of defects in graphene is limited if graphenide oxidation is carried out before exposing the material to water, and that gas removal of water before the incorporation of pre-oxidized graphene is advantageous for the long-term stability of EdG.

Multifaceted experiments and photothermal simulations based analysis of laser induced graphene and its fibers

The interaction of CO2 laser with polyimide results in the formation of laser-induced graphene (LIG) and other morphological transitions based on laser parameters, such as Laser-induced fibers (LIF) on the surface. However, a fundamental investigation of LIF, its properties and potential have not been explored until now. We aim therefore to provide novel insights into the LIF by characterization of its structural, electrical, electrochemical, and mechanical properties. Four different morphologies were identified depending on the laser parameters and the temperature required for their formation were quantified by FEM model. Minimum temperatures of 1800 K were required to form LIG and around 2600 to 5000 K to form LIF. High heterogeneity of the LIF along thickness due to temperature gradients, and the existence of sheet structures underneath the fibers were identified. Due to the loosely bound nature of fibers, LIF dispersion was prepared by ultrasonication to functionalize the carbon electrode for electrochemical characterization. The modification with LIF on the electrodes enhanced the electrochemical response of the electrode towards standard redox couple which confirmed the conductive nature of the fibers. This work provides a solid basis for the versatile tuning of the behavior and properties of LIF for potential applications.