Graphene Oxide Composites Research Articles

Microneedle Electrode Patch Modified with Graphene Oxide and Carbon Nanotubes for Continuous Uric Acid Monitoring and Diet Management in Hyperuricemia.

Hyperuricemia is a common disorder induced by purine metabolic abnormality, which will further cause chronic kidney disease, cardiovascular disease, and gout. Its main pathological characteristic is the high uric acid (UA) level in the blood, so that the detection of UA is highly important for hyperuricemia diagnosis and therapy. Herein, we report a biocompatible and minimally invasive microneedle electrode patch (MEP) for continuous UA monitoring and diet management in hyperuricemia. The composite of graphene oxide and carboxylated multiwalled carbon nanotubes was modified on the microneedle electrode surface to enhance its sensitivity, selectivity, and stability, thus realizing the continuous detection of UA in the interstitial fluid to accurately predict the UA level in the blood. This further allowed us to study the hypouricemic effect of anthocyanins on the hyperuricemia model mouse. It was found that anthocyanins extracted from blueberry can effectively inhibit the activity of xanthine oxidase to reduce the production of UA. The UA level of hyperuricemia model mice fed with anthocyanins is ∼1.7 fold lower than that of the control group. We believe that this MEP offers enormous promise for continuous UA monitoring and diet management in hyperuricemia.

Preparation and Characterisations of Acrylic Epoxy/Polyethylene Glycol/Graphene Oxide Nanocomposites for Antibacterial Coating Applications

This study addresses the urgent need for antibacterial coatings amid escalating concerns about pathogen contamination on various surfaces, particularly in healthcare settings and public spaces where infection control is critical. The development of durable and effective antibacterial coatings could significantly reduce harmful bacteria transmission and improve overall hygiene standards. Graphene oxide (GO) had exceptional antibacterial properties against a wide spectrum of bacteria. Here, the researchers explored the composite of GO with acrylic epoxy (AE) through the use of polyethylene glycol (PEG) to become AE/PEG/GO tertiary nanocomposites in enhancing GO’s antibacterial efficacy. The objectives of this study were to prepare and characterise AE/PEG/GO nanocomposites and then investigate their antibacterial abilities against escherichia coli (E. coli) and staphylococcus aureus (S. aureus) bacteria. The GO was prepared using the modified Hummers method, which was mechanically stirred with AE and PEG to produce the AE/PEG/GO nanocomposites. This was followed by characterisations of the nanocomposites via ultraviolet-visible (UV-Vis) spectrophotometer, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometer and scanning electron microscope (SEM). The nanocomposites were then tested against E. coli and S. aureus bacteria by measuring the diameter of the inhibition zone (DIZ). The results showed that the absorption peak of GO was obtained at a wavelength of 236 nm. The diffraction pattern of the AE/PEG/GO nanocomposites showed amorphous structure with a small and wide peak at 2 around 23°. The IR spectrum of the AE/PEG/GO nanocomposites indicated the presence of –OH, –CH3, –CH2, C=O, C–H, C–O and C=C functional groups. The surface morphology showed well-distributed nanocomposite coating onto glass slides with some micro islands. The nanocomposites exhibited promising antibacterial performance revealing higher efficacy against S. aureus compared to E. coli. This was shown by the performance of AE/PEG/GO coating in inhibiting S. aureus bacteria with 1.55 mm larger DIZ compared to the positive control. However, the AE/PEG/GO coating exhibited smaller DIZ than the positive control with a difference of 3.68 mm in inhibiting E. coli bacteria. This study unveiled a simple and straightforward approach in producing nanocomposites for antibacterial coatings shedding light on their potential applications in safeguarding surfaces against bacterial contamination.

Electrochemical immunosensor for the predictive cancer biomarker SLFN11 using reduced graphene oxide/MIL-101(Cr)-NH2 composite

SLFN11 is a predictive cancer biomarker essential for identifying tumors that are sensitive to DNA-damaging agents, facilitating more personalized and effective treatment approaches. Detecting this biomarker can guide therapeutic decisions and improve outcomes for cancer patients. However, existing detection methods for SLFN11 are complex and require advanced techniques. In this study, we introduce the first immunosensor designed for on-site detection of SLFN11. An advanced electrochemical immunosensor platform utilizing a composite of graphene oxide (GO) and chromium-based metal organic framework (MIL-101 (Cr)-NH2) was developed. The integration of GO and MIL-101(Cr)-NH2 was characterized through FT-IR, XRD, SEM, and XPS, affirming the formation of the composite. The subsequent electrochemical reduction to rGO/MIL-101(Cr)-NH2 significantly improved the electrochemical performance and stability. A glutaraldehyde cross-linker was then utilized to attach the SLFN11-specific antibody to the amine groups of the MOF-modified electrodes. This led to the development of rapid, sensitive, portable, and cost-effective immunosensor for SLFN11 at concentrations as low as 8.9 pg/mL which holds promise for early cancer diagnosis. High specificity was achieved, with minimal cross-reactivity observed with other cancer biomarkers such as pepsinogen I, claudin 18.2 and Programmed cell death protein 1. Demonstrating practical applicability, the electrochemical immunosensor validated by commercial ELISA kit showed successful detection in serum samples with high recovery rates and reproducibility. This research highlights the potential of rGO/MOFs composites in electrochemical biosensors developments for early cancer diagnostics and personalized medicine.

Development of a reagent-free electrochemical disposable sensor strip for the quantification of sweat chloride

In this work, we developed a reagent-free disposable sweat chloride sensor using silver platinum reduced graphene oxide composite. The sensing mechanism involves the silver chloride formation from electro-oxidized silver in the presence of chloride ions. The combination of platinum with silver and reduced graphene oxide resulted in an approximately sixfold increase in sensitivity, significantly enhancing the sensor performance. The developed disposable strip exhibited an excellent sensitivity of 6.592 ± 0.007 and 17.420 ± 0.011 mA (log mM)−1 cm−2 for 5–40 mM and 40–200 mM chloride concentration ranges, respectively with a detection limit of 12 µM. The developed sensor exhibited exceptional selectivity against interfering molecules in sweat samples. The practical applicability of the developed sensor was evaluated in sweat samples, revealing an outstanding sensitivity of 0.901 ± 0.007 mA (log mM)−1 cm−2 for detecting sweat chloride ions. The estimated chloride concentrations are in good agreement with the clinically tested values with a relative error of less than 1.5%. The performance of the fabricated Ag-Pt/rGO/SPE sensor opens advanced point-of-care testing opportunities through non-invasive, and convenient analysis.

Graphene Oxide and Natural Silk as Reinforcements for Epoxy Resin Matrix: Fabrication, Sample Preparation, and Testing

The integration of graphene oxide (GO) and natural silk into epoxy matrices offers a promising approach to developing high-performance composites for structural applications. This study examines the fabrication processes, focusing on sample preparation and testing of GO and natural silk-reinforced epoxy composites. A comprehensive literature review spanning 1990 to 2024 provides insights into the necessity of Vacuum-Assisted Resin Transfer Molding (VARTM) at 30 PSI, the role of ultrasonication in achieving homogeneous GO dispersion, strategies to prevent agglomeration, optimal reinforcement proportions, and challenges encountered during hybridization. Key findings, including the impact of high silk volume fractions (60–70%) on mechanical properties, are incorporated, offering a comprehensive guide for composite fabrication. The findings underscore the critical parameters for successful composite fabrication and performance enhancement. Key Words: Graphene Oxide, Natural Silk, Epoxy Composites, VARTM, Ultrasonication, Hybrid Reinforcements, Structural Applications

Graphene oxide and hydroxyapatite-based composite extracted from fish scale: Synthesis, characterization and water treatment application

In this study the removal of hydrocarbon pollutants from refinery waste water has been described through a convenient adsorption technique using a novel composite of graphene oxide (GO) and n-hydroxyapatite (n-HAp). The main aim was to synthesized composite which are not only sustainable and biodegradable but also exhibit high adsorption capacity and selectivity for hydrocarbon pollutants. Both the HAp and GO were synthesized from fish scales in the laboratory. The synthesized material was then characterized by XRD, FTIR, SEM, and EDX. At 40 °C and 80 min of reaction time, the adsorbent utilized in a batch mode study attained a maximum 97 % organic pollutant adsorption rate. The adsorption activity was spontaneous, exothermic, useful, and it adhered to the pseudo-2nd order kinetic model. without noticeably losing its activity, the adsorbent retained a high level of efficiency over four consecutive cycles. Adsorption of hydrocarbon wastes using composite adsorbent was carried out under batch mode of adsorption experiments. We also studied the effect of dose, temperature, time and pH of the solution on adsorption. Ethanol was used to regenerate the adsorbent, and it was then dried at 70 °C for re-use. The SEM investigation showed that the morphology of huge caves is rough, layered, and wrinkled. The oxygen and phosphate containing groups were found via FT-IR analysis. Freundlich and Langmuir kinetic models were used to measure the adsorption behavior by applying them to the adsorption data. The results demonstrated a strong correlation between the Freundlich isotherm model and the real data. This study showed a highly effective and cost-efficient methodology for the removal of toxic hydrocarbon contaminants in refinery wastewater.

Harnessing carbon-based adsorbents for poly- and perfluorinated substance removal: A comprehensive review

Poly- and perfluoroalkyl substances (PFAS) are synthetic, highly fluorinated chemicals commonly used in products like water-resistant materials, personal care items, non-stick cookware, and cleaning agents. Due to the strength of their CF bonds, PFAS are extremely persistent in the environment, creating significant challenges for pollution control. Traditional degradation methods often prove ineffective, making adsorption a promising alternative for PFAS removal from contaminated water. Carbon-based adsorbents, valued for their sustainability and efficiency, are particularly effective for this purpose. This review provides a detailed analysis on PFAS properties and their removal using various carbon-based adsorbents, including activated carbon, biochar, graphene oxide, carbon nanotubes, and magnetic composites. Adsorption capacities of these materials were seen vary significantly, from as low as 10.7 mg/g for Fe3O4-hybrid biochar, to as high as 713.85 mg/g for functionalized graphene-based adsorbent, highlighting the superior adsorption efficiency of modified graphene adsorbents compared to traditional biochar and activated carbons. Most of these adsorbents fit the Langmuir isotherm model and pseudo-second-order kinetic model with high coefficient of determination, indicating efficient monolayer adsorption and strong interaction with PFAS. The review also explores different adsorption mechanisms, the effects of process parameters on adsorption efficiency, strategies for adsorbent regeneration, and concludes with a bibliometric analysis that highlights key research gaps. These insights are intended to guide future advancements in the development of effective, scalable PFAS remediation technologies using carbon-based adsorbents.

Synthesis, and structural characterization of FeMoO4/r-GO nanocomposite as an electrode material for energy storage application

Improving the energy density of electrochemical supercapacitors requires the urgent development of novel electroactive materials. Metal molybdate-based nanostructures are promising candidates as effective electrode materials for the next generation of energy storage solutions. In the present work, a FeMoO4/r-GO nanocomposite was synthesized via the hydrothermal method and used as anode material for supercapacitor application. The structural, and topographical properties were investigated by XRD, FE-SEM, and TEM analysis. Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission electron microscope (TEM) images of FeMoO4/reduced graphene oxide (r-GO) composites show an irregular, rod-like structure coated with r-GO sheets. The FeMoO4/r-GO nanocomposite electrode material exhibited a remarkable specific capacitance of 240 F/g at the current density of 1 A/g, which is significantly higher than the 167 F/g capacitance of pure FeMoO4. The continued charge–discharge (GCD) (5,000) life cycle performance of FeMoO4/r-GO was the retention and coulombic efficiency of 90 % to 86 % after 10 A/g.

Modifying metal ion ratios in nickel-aluminum layered double hydroxide/reduced graphene oxide composites for selective electrochemical detection of antibiotics

Antimicrobial resistance (AMR) is a global threat that occurs as microorganisms evolve to resist antibiotic (ATB) overuse. To monitor this overuse, inexpensive, affordable, and adaptable sensors are required. While electrochemical sensors are promising, they cannot often distinguish between overlapping electrochemical interactions from multiple ATBs, resulting in poor analyte selectivity. To overcome this challenge, we design electrocatalysts consisting of nickel aluminum layered double hydroxides (NiAl-LDH) and their composites by altering the metal ion ratio to adjust the surface properties and selectivity of sensors. Synthesis of LDH and its graphene oxide (GO) composites is conducted using a low-temperature hydrothermal method. The prepared materials are characterized using various morphological and structural characterization techniques. Electrochemical characterization confirms that tuning the metal ion ratio allows sensors to differentiate between electrochemical reactions, improving the selective detection of amoxicillin and tetracycline from their mixtures. Addition of graphene oxide also enhances sensing capabilities. The optimized sensor has sensitivities of 137.6 nA µM−1 cm−2 and 161.4 nA µM−1 cm−2, and lower detection limits of 4.3 nM and 3.6 nM, respectively, for amoxicillin (Amx) and tetracycline (TC). Interferents have no significant effect on the detection of relatively low concentrations (10 µM) of the two ATBs. The electrodes can also detect the two analytes in tap water samples. This sensor methodology can potentially improve environmental antibiotic detection to mitigate the risk of antimicrobial resistance.

Significantly Enhanced Nitrate Removal by Nanoscale Zerovalent Iron–Reduced Graphene Oxide Composites via Biological Denitrification: Performance and Mechanism

Significantly Enhanced Nitrate Removal by Nanoscale Zerovalent Iron–Reduced Graphene Oxide Composites via Biological Denitrification: Performance and Mechanism

Enhancing microbial fuel cell performance with free-standing three-dimensional N-doped porous carbon anodes

Microbial fuel cells (MFCs) utilize microorganisms as catalysts to transform the chemical energy to electrical power. However, the practical application of MFCs is currently impeded by low power output, which is caused by insufficient microbial colonization on the anode, slow extracellular electron transfer at the microbe-anode interface, and low oxygen reduction reaction catalytic efficiency at the cathode. Herein, a three-dimensional (3D) hierarchical porous anode of Carbonization-CTS-MF/rGOtempreture (CCMF/rGOT) by pyrolyzing crosslinked composite of melamine formaldehyde resin (MF), chitosan (CTS) and graphene oxide (GO). The macroporous anode provides a biocompatible surface for exoelectrogens and 3D electron transfer pathways. In addition, an appropriate balance of graphitic-N and pyrrolic-N content optimizes both conductivity and the number of active sites, thereby synergistically enhancing extracellular electron transfer (EET) efficiency. Therefore, the power density of CCMF/rGO1000 anode is 11.28 W/m3, which surpasses the CCMF1000 anode without 3D reduced graphene oxide (rGO) conductive network (10.04 W/m3), and traditional carbon cloth anode (4.36 W/m3). Moreover, the anode runs stably for more than 200 days with a maximum operating voltage of 0.69 V, which achieves chemical oxygen demand (COD) removal rate of 95.4 %. This work provides a promising strategy to prepare a free-standing 3D anode with enriched exoelectrogens and enhanced EET to improve the MFCs performance.

Bimetallic Sulfide Hollow Nanocubes Heterostructure Promotes Dual Coupling of Conversion and Alloying/Dealloying Reactions to Achieve Durable Potassium-Ion Battery Anode.

Conversion and alloying-type transitional metal sulfides have attracted significant interests as anodes for Potassium-ion batteries (PIBs) and Sodium-ion batteries (SIBs) due to their high theoretical capacities and low cost. However, the poor conductivity, structural pulverization, and high-volume expansions greatly limit the performance. Herein, Co1-xS/ZnS hollow nanocube-like heterostructure decorated on reduced graphene oxide (Co1-xS/ZnS@rGO) composite is fabricated through convenient hydrothermal and post-heat vulcanization techniques. This unique composite can provide a more stable conductive network and shorten the diffusion length of ions, which exhibits a remarkable initial charge capacity of 638.5mA h g-1 at 0.1 A g-1 for SIBs and 606mA h g-1 at 0.1 A g-1 for PIBs, respectively; It is worth noting that the composite presents remarkable long stable cycle performance in PIBs, which initially delivered 274mA h g-1 and sustained the charge capacity up to 245mA h g-1 at high current density of 1 A g-1 after 2000 cycles. A series of in situ/ex situ detections and first principle calculations further validate the high potassium ions adsorption ability of Co1-xS/ZnS anode materials with high diffusion kinetics. This work will accelerate the fundamental construction of bimetallic sulfide hollow nanocubes heterostructure electrodes for energy storage applications.

New Schiff base covalently bonded graphene oxide for removing chromium(VI) from surface runoff

Hexavalent chromium (Cr(VI)) poses severe health and environmental risk, especially in industrial vicinities where runoff concentrations are elevated by evaporation and sedimentation dynamics. This study investigates the utilization of modified graphene oxide (GO) with abundant active groups as an adsorbent. The novel adsorbent, GO/ATA, was synthesized by covalently attaching a Schiff base (ATA) to GO via a coupling reaction, enhancing its adsorptive properties. The physicochemical properties of GO/ATA were meticulously characterized to ascertain structural and morphological attributes. GO/ATA exhibit exceptional adsorptive capabilities, surpassing the performance parameters of other adsorbents with a maximum of 243.3 mg g−1 at 298 K. The electrostatic attraction between the N-containing functional groups in the graphene oxide and Schiff base composite (GO/ATA) and Cr(VI) is the main mechanism behind the adsorption process; Subsequently, a reduction reaction occurs, facilitated by the thiol and N-containing functional groups in GO/ATA composite, resulting in the transformation of Cr(VI) into Cr(III). This transformation is essential for the following chelation process occurring on the surface of the adsorbent material. Evaluations of recyclability indicated that GO/ATA retains substantial adsorption efficacy, with a reduction from 91.2% to 72.7% over five cycles, thus affirming its recyclability and practical application in the remediation of Cr(VI)-contaminated waterborne environment. Additionally, GO/ATA's effectiveness in removing Cr(VI) from surface runoff was specifically tested, emphasizing its economic and environmental viability.

Structural and optical study of chitosan–graphene oxide composite through hydrothermal route

Chitosan (CS), a semi-crystalline biomolecule, has gained widespread attention due to its great synthesis flexibility and biological compatibility. In this study, chitosan was synthesized from chitin, a homopolymer of N-acetyl-D-glucosamine linked by β–(1→4) bonds extracted from shrimp shell. Crystallinity of chitosan was always an issue while applying it in various applications. Graphene Oxide (GO) can be a very capable substitute for enhancing the crystallinity of chitosan due to its mechanical, thermal, optical, biomedical, and electronic properties. In this study, a chitosan–graphene oxide composite was synthesized by following the hydrothermal method. The characterization of chitosan–graphene oxide composite performed by different processes: x-ray diffraction revealed that the produced chitosan–graphene oxide composite has improved crystalline characteristics, with a smaller crystallite size of 6.2 nm when compared to GO and CS. Fourier transform infrared spectroscopy confirmed the presence of functional groups in GO, CS, and GO–CS. The Raman spectrum predicted the increased disorders originated from sp2 carbon hexagonal networks with strong covalent bonds. The relative quality and successful preparation of the GO–CS composite were evaluated and confirmed by ultraviolet spectroscopy. The scanning electron microscopy (SEM) analysis pictured the morphology of the GO-CS composite. The novel aspect of this study was the incorporation of graphene oxide in order to boost the crystal structure of chitosan derived from raw shrimp shells.

Mechanism of selective uranium adsorption using polyvinyl alcohol /Cyphos IL-101 / reduced graphene oxide composites

A novel composite material for uranium extraction from seawater, APGO, was prepared by crosslinking reduced graphene oxide (rGO) loaded with trihexyl(tetradecyl)phosphonium chloride (Cyphos IL-101) with polyvinyl alcohol. The experimental results indicate that the surface of APGO contains functional groups, such as carboxyl, hydroxyl, and phosphate, that have adsorption properties for uranium. APGO exhibits excellent hydrophilicity and stability while preserving the intact two-dimensional network structure of rGO. The specific surface area of APGO was 9.23 m2/g with an average pore size of 27.50 nm. Furthermore, the optimal pH range for APGO to adsorb uranium is 6–8, making it more suitable for extracting uranium from seawater. Notably, the selective adsorption capacity of APGO for uranium is significantly enhanced compared to that of AGO, with a Kd value approximately 4.6 times higher than that of AGO. The theoretical adsorption capacity is 467mg/g at 318 K (pH = 6). The process of uranium adsorption by APGO is a spontaneous endothermic reaction. The adsorption performance of APGO is noteworthy because it exhibits only a 2 % decrease after five adsorption–desorption cycles. Furthermore, APGO demonstrates commendable recyclability. Overall, APGO demonstrates a remarkable affinity for uranium and promising potential for efficiently extracting uranium from seawater.

A three-components-based disposable electrochemical sensor for the detection of heavy metal ions in water

The development of an efficient sensor based on a novel three-components nanocomposite is presented for the detection of heavy metal ions (Cd2+ and Pb2+) in water. For the preparation of three-components nanocomposite surface, the polydopamine reduced graphene oxide (PyDA/RGO) composite was initially prepared by a one-step polymerization of dopamine (DA) on RGO followed by surface modification of the prepared composite with cysteine (Cys). The formation of three-components nanocomposite surface (i.e., Cys/PyDA/RGO) was initially confirmed through physical characterization techniques, including X-ray diffraction and infrared spectroscopy, whereas scanning electron microscopy revealed the surface morphology after each step of sensor fabrication. The electrochemical properties of the sensing platform were evaluated through electrochemical techniques, including cyclic voltammetry and electrochemical impedance spectroscopy with an external ferri‐−/ferrocyanide redox probe. The prepared three-components nanocomposite on disposable pencil graphite electrode (Cys/PyDA/RGO/PGE) showed an improved charge transfer rate as compared to PyDA/RGO/PGE and bare PGE electrode. Targeted heavy metal ions were detected on the sensor surface using differential pulse voltammetry with greater sensitivity, showing detection limits of 0.77 and 1.13 ppb for Cd+2 and Pb+2 ions in citrate buffer solution, respectively. The sensor demonstrated comparable performance in the tap water samples.

Enhanced Mechanical Properties and Degradation Control of Poly(Lactic) Acid/Hydroxyapatite/Reduced Graphene Oxide Composites for Advanced Bone Tissue Engineering Application.

This study explores the enhancement of poly(lactic acid) (PLA) matrix using calcium hydroxyapatite (cHAP) and reduced graphene oxide (rGO) for developing composite scaffolds aimed at bone regeneration applications. The PLA composites were fabricated through solvent evaporation and melt extrusion and characterized by various techniques, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and mechanical testing. The incorporation of cHAP and rGO significantly improved the thermal, mechanical, and morphological properties of the PLA matrix. Mechanical testing revealed that adding 10% cHAP and varying amounts of rGO (0.1%, 0.3%, 0.5%) enhanced tensile and compressive strengths, with the highest improvements observed at 0.5% rGO content. Thermal analysis showed increased thermal stability with higher degradation temperatures for the composites. Spectroscopic analyses confirmed the effective integration of cHAP and rGO into the PLA matrix with characteristic peaks of the fillers identified in the composite spectra. In vitro, degraded action tests in phosphate-buffered saline (PBS) at pH 7.4 over 12 months indicated that composites with higher rGO content exhibited lower mass loss and better mechanical stability. Furthermore, finite element analysis (FEA) simulations were performed to validate the experimental results, demonstrating a strong correlation between simulated and experimental compressive strengths. This novel approach demonstrates the potential of PLA/cHAP/rGO composites in creating effective and biocompatible scaffolds for tissue engineering, providing a comprehensive analysis of the synergistic effects of cHAP and rGO on the PLA matrix and offering a promising material for bone regeneration applications.

Electrochemical sensing of gatifloxacin using Ag2S/RGO nanocomposite

As a widely-used fluoroquinolone antibiotics, 1-Cyclopropyl-6-fluoro-8-methoxy-7-(3-methyl-1-piperazinyl)-4-oxo-1,4-dihydro-3-quinolinecarboxylic acid (gatifloxacin, GAT) has aroused much concern recently and it is of great importance to realize the accurate and efficient detection. Herein, the silver sulfide/reduced graphene oxide composite (Ag2S/RGO) was synthesized with one-pot method and was coated on the glassy carbon electrode to develop an effective electrochemical sensor for GAT. After the optimization of the size of Ag2S, the pH of buffer solution, and the scanning rate, the Ag2S/RGO modified electrode exhibits good linear relationship to GAT within wide ranges of 0.2 µM − 20 µM and 20 µM − 250 µM with a detection limit of 0.0667 µM. Besides, the proposed sensor shows good selectivity to GAT versus multiple interferences, including organic compounds, ions, and other antibiotics. At last, the proposed sensor was successfully applied in the GAT analysis in various real samples (including shrimp, fish, and chicken) with satisfying recoveries of 91.8 % − 102.4 %. In general, the proposed Ag2S/RGO-based electrochemical sensor provides a novel strategy for the GAT analysis, which is of significance for the development of efficient analytical techniques for antibiotics.

Integrating recognition peptide into a nanozyme to mimic uricase binding pocket as a multifunctional nanoplatform for highly selective uric acid recognition, sensing and degrading

Nanozyme based colorimetric sensor for physiological biomarkers detection is becoming an increasingly influential technology in diagnosis, but the selective discrimination of biomarkers using single nanozyme without natural enzyme is greatly challenging. Here, a colorimetric detection platform for biomarker is successfully constructed by integrating recognition peptide (RGPT) into a nanozyme to mimic the binding pocket in natural enzyme. Firstly, RGPT-ultrafine palladium nanoparticles (PdNPs)@reduced graphene oxide (rGO) composite was facilely prepared using an arginine-rich RGPT. RGPT-PdNP@rGO composite displays outstanding laccase-like activity with Km being 0.075 mM at significantly low dosage used, which is one magnitude lower than that of natural enzyme. RGPT-PdNP@rGO nanozyme based one-step sensor can selectively detect uric acid (UA) with a comprehensive linear range from 0.2 to 110 μM and a limit of detection of 120 nM. Moreover, RGPT-PdNP@rGO composite displays an outstanding activity for UA oxidation with Km being 0.024 mM, revealing the nanozyme exhibits a similar affinity towards UA as natural uricase due to the cooperation of the three components. Compared with our previous work, these extremely improved UA recognition, sensing and degrading performances not only support the role of RGPT in enhancing with the recognition ability of the composite nanozyme for targeted UA, but also reveal the recognition role of RGPT is associated closely with inorganic components in the composite. This work provides more definitive and comprehensive information about multifunctional nanozymes for precise biomarker recognition by introducing recognition peptide, which is highly significant for applications beyond mimic-enzyme catalyst, including theranostic, sensing, and energy fields.

Relaxation dynamics and conductivity in poly(vinylidene fluoride)/graphene oxide composites

The αc relaxation, which originates from the crystalline phase of Poly(vinylidene fluoride), is studied in the composite system of Poly(vinylidene fluoride) and Graphene oxide. PVDF/GO composites were prepared using solvent casting. The crystalline phases in PVDF/GO composites were identified using XRD and quantified using FTIR. The thermal properties were analyzed using DSC, and the crystallization degrees were calculated. The electric modulus formalism is employed to understand the relaxation mechanism with temperature. AC conductivity studies reveal the activation energy for conduction in these composites.