Reduced Graphene Oxide Nanoparticles Research Articles

Interface engineering-induced enhancements in sodium-ion batteries: A nexus of ZnS nanoparticles and reduced graphene oxide for augmented storage and conductivity

Due to the inherent sluggish kinetics and the pronounced volumetric expansion of zinc sulfide (ZnS), it has become a prevalent modification strategy to regulate its morphology and composite with graphene for using ZnS as anodes in sodium-ion batteries (SIBs). Nevertheless, the elucidation of mechanisms underpinning the electrochemical performance facilitated by graphene incorporation remains scant. To further describe the synergistic mechanism, the ultrafine ZnS nanoparticles anchored on reduced graphene oxide (rGO) were synthesized through a simple solvothermal method. Research shows that the ZSG (ZnS nanoparticles-reduced graphene oxide composite) electrode suggests superior rate capability, maintaining a reversible specific capacity of 228.6 mAh·g−1 upon returning from a high current density of 5 A·g−1. Furthermore, the nanoscale integration of ZnS particles with rGO synergistically mitigates the structural expansion of the ZSG electrode encountered during cycling, thereby decelerating the degradation of cyclic performance. Insights gleaned from first-principles calculations and comprehensive electrochemical evaluations reveal that the built-in electric field, engendered within the composite architecture, substantially augments charge transfer ability and mitigates the energy barriers impeding sodium ion (Na+) diffusion accordingly. Consequently, the methodology adopted for synthesis and the synergistic modification mechanism can proffer a reference for the design of advanced anode materials in SIBs.

Polyaniline/reduced graphene oxide nanocomposites for electrochemical and solar cell applications

Polyaniline nanocomposites are synthesized via in situ chemical oxidation method by reinforcing reduced graphene oxide nanoparticles of various weight percentage. Structural, optical, thermal and electrochemical studies are performed to know the significance of introducing reduced graphene oxide into polyaniline and to analyse the importance of filler weight percentage in determining various properties of the nanocomposites. X-ray diffraction peak intensity is appeared to be maximum for nanocomposite doped with 2% filler. This composite shows minimum crystallite size and maximum photoluminescence intensity. Maximum ID/IG ratio obtained for 2% filler added nanocomposite from Raman spectroscopy studies proved that the presence of more surface defects and recombination of charge carriers are the reasons for enhanced photoluminescence. Thermal stability is found to be better for a nanocomposite with 1% reduced graphene oxide and obtained a mass retention of 60% even after heating up-to 600 °C. SEM images give various shapes of nanocomposite such as nanorods, spherical nanoparticles and button shaped nanocomposites for different filler weight percentage. Carbon to oxygen ratio is observed to be decreased as the filler percentage increased from 1% to 4% in SEM-EDAX analysis. Polymer nanocomposite with 1% reinforcement possess maximum UV and visible absorption and is found to be decreased as filler concentration increased from 1 to 4%. Electrochemical analysis is performed for polyaniline and 1% reduced graphene oxide reinforced polyaniline nanocomposite. Specific capacitance of the electrode is obtained as 212 F g−1 and 609 F/g for polyaniline and nanocomposite respectively at a scan rate of 0.01 V/S. Solar cell device performance study shows that power conversion efficiency is 5.54% for 1% reduced graphene oxide nanocomposite, 4.7% for 2% reinforced, 4.16% for 3% filler and 3.61% for 4% nanocomposite.

Synergistic Effects of Heated Walnut Shell Powder and Reduced Graphene Oxide in Paraffin Wax Composites for Marine Thermal Applications

The study focuses on creating and analyzing paraffin wax composites enriched with heated walnut shell powder and reduced graphene oxide nanoparticles. Experimental procedures include careful blending of materials to form homogeneous mixtures, followed by analysis using techniques such as thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The composites show improved thermal properties compared to pure paraffin wax, with increased melting temperatures, heat of fusion, and thermal conductivity. The study also examines density and thermal diffusivity, providing insights into thermal behavior. Additionally, it ensures the corrosion resistance of nano-enhanced bio-based phase change materials (PCMs) for marine engineering through thorough material selection, corrosion testing, and long-term exposure studies simulating seawater conditions. The study evaluates environmental impacts, toxicity, and compliance with standards and proposes mitigation strategies like protective coatings and encapsulation techniques. Overall, the research contributes to developing environmentally sustainable PCM materials for marine applications and offers insights into their thermal behavior for thermal energy storage and management.

An ultrasensitive genosensor for detection of toxigenic and non-toxigenic Clostridioides difficile based on a conserved sequence in surface layer protein coding gene

Clostridioides difficile (C. difficile) is the most common agent of antibiotic-associated diarrhea, leading to intestinal infection through the secretion of two major toxins. Not all strains of this bacterium are toxigenic, but some of them cause infection via their accessory virulence factors, such as surface layer protein (SlpA). SlpA is conserved in both toxigenic and non-toxigenic strains of C. difficile. In the present work, an amplification-free electrochemical genosensor was designed for the detection of the slpA gene. A glassy carbon electrode coated with gold nanoparticle-reduced graphene oxide nanocomposite was used as the working electrode, and its surface was modified using a simple thiolated linear oligonucleotide as the bioreceptor. Moreover, the hexaferrocenium tri[hexa(isothiocyanato) iron(III)] trihydroxonium (HxFc) complex was used as an intercalator, and its redox signal was recorded using differential pulse voltammetry. Scan rate studies indicated a quasi-reversible adsorption-controlled process for the HxFc complex. This genosensor showed high sensitivity with a limit of detection of 0.2 fM, a linear response range of 0.46–1900 fM, and a satisfactory specificity toward the synthetic slpA target gene. Also, the genosensor indicated responses in the mentioned linear range toward the genome extracted from either toxigenic or non-toxigenic strains of C. difficile.

Concanavalin A as carrier for sensitive electrochemical immunosensor based on AgNPs-rGO signal amplification

Concanavalin A (ConA), as a carrier for immobilizing antibodies, was used for the first time in electrochemical immunosensor. In this work, a label-free electrochemical immunosensor based on Ag nanoparticles-reduced graphene oxide (AgNPs-rGO) nanocomposite and ConA was successfully prepared to detect arsanilic acid (ASA). AgNPs-rGO nanocomposite displayed superior conductivity and redox capability. Specially, ConA showed excellent binding ability with monoclonal antibody of ASA through lectin-sugar interactions. Under the optimized conditions, the proposed electrochemical immunosensor showed a linear dependence over ASA concentrations ranging from 0.025 ng/mL to 25 ng/mL with a low detection limit of 0.011 ng/mL. Furthermore, the immunosensor was used to monitor ASA in chicken and egg with good precision and accuracy. In conclusion, the simple and low-cost immunosensor was desirably applied as a useful candidate for detection of ASA in animal derived food.

Electro-sensing of biocide and its applications based on the Ru-doped TiO2 and reduced GO nanocomposite fabricated electrode

In this study, we utilized a carbon paste electrode (CPE) that had been modified with reduced graphene oxide nanoparticles (rGO) and ruthenium-doped TiO2 nanoparticles (Ru–TiO2) to conduct an electrochemical investigation of triclosan (TCS). To characterize the synthesized Ru–TiO2 nanoparticles, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were utilized. Electrochemical impedance spectroscopy was employed to characterize the fabricated Ru–TiO2/rGO/CPE and bare CPE. “The heterogeneous rate constant, the pH study, the accumulation time, the scan rate, and the concentration fluctuation were investigated. Combining several electrocatalytic modifiers allows for the development of effective electrochemical sensors. Ru–TiO2 and rGO nanostructures are two examples of these modifiers. As a result of its great sensitivity, selectivity, and application to the measurement of TCS, nanostructured Ru–TiO2 and rGO are highly recommended in this research. At a pH of 9.2 in PBS, the sensitivity range of a Ru–TiO2/rGO/CPE was investigated by testing its response to a calibration plot of TCS concentrations ranging from 1.0 × 10−8 M to 2.2 × 10−7 M. Voltammetric techniques such as square wave voltammetry (SWV) and cyclic voltammetry (CV) were used to determine the electrochemical components that comprise TCS. The developed sensor was also employed to detect and analyze TCS levels in actual samples, including those of fruits, vegetables, water, and soil.”

Waste Cooking Oil Biodiesel and Their Nanobiodiesel Blends Infused with Reduced Graphene Oxide (RGO) Nanoparticles for Diesel Engine Applications

This work focusses on the potential application of waste cooking oil (WCO) as alternative to diesel as it is abundantly, locally available. The oil is subsequently converted into its biodiesel called waste cooking biodiesel (WCOBD). GCMS studies of the waste cooking oil and its biodiesel is carried out to determine the fatty acid composition. Further WCOBD is blended with diesel to produce its WCOBD B20 blend. The physio-chemical properties of the WCO, WCOBD, WCOBD B20 and their nano-biodiesel blends were determined and were compared with diesel. These properties of WCOBD B20 are in good agreement with diesel. This B20 blend can successfully provide 20% substitute to fossil diesel and save foreign exchange besides providing energy security to India. The fuel properties of the WCOBD B20 blends are further modified by adding carbon derived nanoparticles of reduced graphene oxide (RGO) to prepare nano-biodiesel blends. The percentage of RGO nanoparticles were varied from 20% to 100 % by volume insteps of 20% using suitable SDS surfactants. The stability of these nano-biodiesel blends is determined by using zeta potential method. The stability of decreased with increase in the nano-particle dosage in base biodiesel blends. Accordingly, the blends with dosage beyond 80% showed lower stability in terms of lower zeta potential values. The nano-biodiesel blends showed improvement in calorific value and self-ignition temperature compared to the B20 biodiesel blend. Among the Nano-biodiesel blends considered WCOME B20 RGO80 showed comparatively higher BTE (11.67%), reduced emissions of smoke opacity (14.63%), HC (21.42%), CO (16.67%), ID (10%), CD (16.67%) and increased NOx (2.5%), and PP (15.38%) respectively when compared to the WCOBD B20 blend.

Zinc oxide nanoparticles-reduced graphene oxide nanocomposite thin-film for β-D-glucose detection

This work presents a technique to detect β-D-glucose by using zinc oxide nanoparticles-reduced graphene oxide (ZnO NPs-rGO) nanocomposite thin-film. The ZnO NPs were synthesized by the direct precipitation method. The rGO was fabricated via hydrothermal treatment of graphene oxide (GO) powder. The optical properties of the nanocomposite thin-film were characterized via ultraviolet–visible, Raman and photoluminescence (PL) spectrometers. The morphology of the nanocomposite thin-film was obtained from a field emission scanning electron microscope (FESEM). Based on the optical result, the absorption peak was correlated with the excitation wavelength required to induce high PL spectra in the nanocomposite. Furthermore, the FESEM image displayed the spherical and non-uniform sized ZnO NPs on the sheet-like surface of rGO. For the β-D-glucose detection, changes in the wavelength and intensity peak of UV emission in PL spectra were investigated. From the results, a red-shift and reduction of peak intensity of UV emission was observed under 0.25 - 40 mM β-D-glucose concentration. A linear response, with a slope of 0.87 nm/mM and regression coefficient, R2 of 0.99 indicated that the detection range of the nanocomposite thin-film covers from high to low glucose levels. Furthermore, the highest sensitivity of 1.09 %/mM was obtained based on the percentage change of the peak intensity per mM glucose concentration. These observations signify the potential of detecting wide concentrations of β-D-glucose, making the nanocomposite material suitable for practical uses in glucose sensing and monitoring.

Acoustic shock wave processing on amorphous carbon quantum dots – correlation between spectroscopic-morphological–magnetic and electrical conductivity properties

In this context, we report the acoustic shock wave processing on amorphous Carbon quantum dots (a-CQD) such that its degree of graphitization and magnetic properties are analyzed. Analytical techniques such as the Raman spectrometer, high resonation–transmission electron microscopy (HR-TEM) and vibrating sample magnetometer (VSM) are utilized to understand the structural, morphological and magnetic properties changes under shocked conditions. The Raman spectroscopic data reveal that the ID/IG ratio is slightly reduced under shocked conditions and the observed values are 0.78, 0.77 and 0.75 for the respective 0, 150 and 300 shocked conditions. The formation of ultra-short-range graphitic nanostructures is confirmed by HR-TEM results at the 300-shocked condition. The most convincing and supporting results for the enhancement of the degree of graphitization are found by the outcome of the magnetic properties such that the saturation magnetization (Ms) is found to be linearly reduced with respect to the number of shock pulses and the observed values are 0.869, 0.757 and 0.710 emu/g for the 0, 150 and 300 shocked conditions, respectively. The electrical resistance of the a-CQD is found to be linearly reduced with respect to the number of shock pulses due to the reduction of sp3 carbon networks. The formation of crystalline graphitic nanostructures in amorphous CQD is explained on the basis of the hot-spot nucleation mechanism. Based on the obtained Raman, HR-TEM and VSM results, during the shocked conditions, slight enhancement of the graphitization is observed; however, from the structural stability point of view, the Carbon dots have high shock resistance than that of the amorphous carbon nanoparticles, multi-wall carbon nanotubes, and reduced graphene oxide nanoparticles. Hence, the title quantum dots can be strongly considered for the applications of device fabrication.

Evaluation of treatment and energy efficiencies of an advanced electrochemical system for Chlorella removal equipped with aluminum, graphite, and RGO nanoparticles-coated cathodes

Advanced material sciences and technologies can help to address environmental challenges in order to achieve sustainable development goals by developing innovative materials capable of mitigating energy consumption in treatment systems. In this study, an innovative electrocoagulation unit for algae removal was optimized, and the effects of various variables, including novel cathode materials (i.e., graphite and reduced graphene oxide nanoparticles), on treatment efficiency and energy consumption were evaluated. Reduced graphene oxide nanoparticles were synthesized and then immobilized on the graphite cathode surface with the modified Hummer's method. Stabilization of nanoparticles was achieved with polytetrafluoroethylene. The use of the reduced graphene oxide nanoparticles-coated cathode led to a significant decrease (42.93%) in energy consumption, compared to the case with an aluminum cathode. In the optimum conditions (a current density of 3 mA/cm2, an electrolyte concentration of 2 g/L, an electrode surface area of 56 cm2, a processing time of 60 min, and a sedimentation time of 30 min), the novel electrocoagulation unit, equipped with an aluminum anode and a reduced graphene oxide nanoparticles-coated cathode electrode, achieved removal efficiencies of 72.69% for Chlorella species and 72.96% for turbidity.

Enhanced Polarization Properties of Holographic Storage Materials Based on RGO Size Effect.

Polarized holographic properties play an important role in the holographic data storage of traditional organic recording materials. In this study, reduced graphene oxide (RGO) was introduced into a phenanthraquinone-doped polymethylmethacrylate (PQ/PMMA) photopolymer to effectively improve the orthogonal polarization holographic properties of the material. Importantly, the lateral size of RGO nanosheets has an important influence on the polymerization of MMA monomers. To some extent, a larger RGO diameter is more conducive to promoting the polymerization of MMA monomers and can induce more PMMA polymers to be grafted on its surface, thus obtaining a higher PMMA molecular weight. However, too large of a RGO will lead to too much grafting of the PMMA chain to shorten the length of a single PMMA chain, which will lead to the degradation of PQ/PMMA holographic performance. Compared with the original PQ/PMMA, the diffraction efficiency of the RGO-doped PQ/PMMA photopolymer can reach more than 11.4% (more than 3.5 times higher than the original PQ/PMMA), and its photosensitivity is significantly improved by 4.6 times. This study successfully synthesized RGO-doped PQ/PMMA high-performance photopolymer functional materials for multi-dimensional holographic storage by introducing RGO nanoparticles. Furthermore, the polarization holographic properties of PQ/PMMA photopolymer materials can be further accurately improved to a new level.

Nanostructured Fe-N-C Electrocatalysts with CeO2 Additives for PEM Fuel Cells

The development of cost-effective electrocatalysts for polymer electrolyte membrane fuel cells (PEM fuel cells) is essential for the widespread use of this technology. The high cost and limited availability of Pt-group metals (PGMs) used as catalyst materials are the main barriers to the widespread commercialization and development of PEM fuel cells. [1] Therefore, the use of high surface area and effective catalysts without Pt have gained great importance in PEM fuel cells. This study introduces high surface area electrocatalysts that are free of platinum group metals (non-PGM) consisting of iron-nitrogen-carbon (Fe-N-C). Here, the uniform distribution of Fe was achieved using graphene oxide (GO) nanoparticles to enhance the catalyst's performance for oxygen reduction reaction (ORR). [2] Furthermore, the addition of a small amount of cerium oxide (CeO2) nanoparticles to the catalyst layer helps to prevent the degradation of the catalyst and ionomer by preventing H2O2 formation as well as increasing the ORR activity due to high oxygen storage capacity. [3] Initially, GO is synthesized by improved Hummer’s method. The GO nanoparticles are obtained through a process involving ball-milling and acid treatment. These nanoparticles are then thermally reduced and nitrogen-doped to form nitrogen-doped reduced graphene oxide nanoparticles. Fe-N-C complexes are synthesized by reacting these nanoparticles with FeCl2 precursor, which are then hydrothermally treated to introduce CeO2 additives. The resulting catalysts are analyzed using various techniques (FT-IR, XPS, SEM, TEM, EDX) and display excellent electrochemical performance. The ORR activity of the Fe-N-C catalysts was investigated and compared with the electrocatalysts prepared with larger graphene oxide particles. A similar comparison is also made with and without CeO2 additives. The authors gratefully acknowledge the financial support of The Scientific and Technological Research Council of Turkey (TÜBİTAK) (Grant Number: 122M429) References [1] He, C., Desai, S., Brown, G., & Bolleplli, S. (2005). PEM fuel cell catalysts: Cost, performance, and durability. The electrochemical society Interface, 14(3), 41.[2] Weiss, J., Zhang, H., & Zelenay, P. (2020). Recent progress in the durability of Fe-NC oxygen reduction electrocatalysts for polymer electrolyte fuel cells. Journal of Electroanalytical Chemistry, 875, 114696.[3] Taşdemir, A., Iskandarani, B., Yürüm, A., Gürsel, S. A., & Kaplan, B. Y. (2021). CeO2 nanorod decorated NrGO additives for boosting PEMFC performance. International Journal of Hydrogen Energy, 46(63), 32250-32260.

Fe3O4 nanoparticles decorated reduced graphene oxide&carbon nanotubes-based composite for sensitive detection of imatinib in plasma and urine

In this study, a new reduced graphene oxide (rGO) has been synthesized via a facile and envi­ronmentally friendly process using Callicarpa maingayi leaf extract. A novel magnetic catalyst based on Fe3O4 nanoparticles-reduced graphene oxide&carbon nanotubes ((Fe3O4--(rGO&CNT)) was prepared and characterized by hydrothermal method. The Fe3O4 nanoparticles with an average size of 25 to 40 nm were placed on carbon nanotubes and reduced graphene oxide sheets, while carbon nanotubes inserted between the reduced graphene oxide sheets effectively prevented their aggregation. The (Fe3O4-(rGO&CNT) composite has a large surface area and good electrocatalytic properties, suiting for the detection and determination of imatinib (IM) anticancer drug by voltammetry method. Under opti­mi­zed conditions, good linearity was achieved in the concentration range of 0.1 to 40 μmol L-1 and the limit of detection and sensitivity were 57 nmol L-1 and 3.365 μA L μmol-1, respectively. Furthermore, the fabricated sensor demonstrated acceptable reproducible behaviour and accuracy and a high level of stability during all electrochemical tests. In addition, the proposed method was applied for the detection of IM in biological samples and the recoveries were 94.0 to 98.5 %, with relative standard deviations of 2.1 to 4.4 %.

Interface and magnetic-dielectric synergy strategy to develop Fe3O4-Fe2CO3/multi-walled carbon nanotubes/reduced graphene oxide mixed-dimensional multicomponent nanocomposites for microwave absorption

Interfacial and/or magnetic-dielectric synergistic effects are important avenues to boost microwave absorption properties. In order to simultaneously utilize these effects, we elaborately designed mixed-dimensional Fe3O4-FeCO3/multi-walled carbon nanotubes (MWCNTs)/reduced graphene oxide (RGO) multicomponent nanocomposites (MCNCs) in large scale via a facile process of hydrothermal and freeze-drying. The microstructural investigation revealed that two-dimensional RGO, one-dimensional MWCNTs and zero-dimensional Fe3O4-FeCO3 nanoparticles were well bounded to generate the typical mixed-dimensional structure. By controlling the amounts of initial reactants, the Fe3O4-FeCO3/MWCNTs/RGO MCNCs displayed improved impedance matching features, polarization and conduction loss abilities, which lead to the evidently improved electromagnetic absorption properties. The Fe3O4-FeCO3/MWCNTs/RGO MCNCs simultaneously exhibited excellent absorption ability, large absorption bandwidth, low density and thin matching thickness. Generally, this work not only proposed an effective route to make the best of magnetic-dielectric synergy and interfacial strategy for exploiting novel microwave absorption materials, but also presented a simple approach to synthesize magnetic MWCNTs/RGO-based mixed-dimensional MCNCs.

Faraday cage-type self-powered immunosensor based on hybrid enzymatic biofuel cell.

Self-powered immunosensors (SPIs) based on enzymatic biofuel cell (EBFC) have low sensitivity and poor stability due to the high impedance of the immune sandwich and the vulnerability of enzymes to environmental factors. Here, we applied the Faraday cage-type sensing mode on a hybrid biofuel cell (HBFC)-based SPI for the first time, which exhibited high sensitivity and stability. Cytokeratin 19 fragment (CYFRA 21-1) was used as a model analyte. Au nanoparticle-reduced graphene oxide (Au-rGO) composite was used as the supporting matrix for immunoprobe immobilized with detection antibody and glucose dehydrogenase (GDH), also the builder for Faraday cage structure on the bioanode in the presence of antigen. After the combination of immunoprobe, antigen, and the antibody on the bioanode, the Faraday cage was constructed in case the AuNP-rGO was applied as a conductive cage for electron transfer from GDH to the bioanode without passing through the poorly conductive protein. With the assistance of the Faraday cage structure, the impedance of the bioanode decreased significantly from 4000 to 300 Ω, representing a decline of over 90%. The sensitivity of the SPI, defined as the changes of open circuit voltage (OCV) per unit concentration of the CYFRA 21-1, was 68 mV [log (ng mL-1)]-1. In addition, Fe-N-C was used as an inorganic cathode material to replace enzyme for oxygen reduction reaction (ORR), which endowed the sensor with 4-week long-term stability. This work demonstrates a novel sensing platform with high sensitivity and stability, bringing the concept of hybrid biofuel cell-based self-powered sensor.

Fabrication of a citrus flavonoid hesperetin-capped gold nanoparticles-reduced graphene oxide nanocomposites (Hes-Au/rGONCs) as a potential therapeutic agent for triple negative breast cancer and bacterial infections

Hesperetin (Hes) is a Citrus Flavonoid, which is confirmed to have extensive therapeutic effects, comprising antimicrobial, antioxidant, anticancer, cardiovascular protection, and so forth. To overcome the poor solubility, here we attempt to synthesize the Hes-mediated gold nanoparticles bio-functionalized in reduced Graphene oxide (Hes-Au/rGONCs) to increase the therapeutic efficacy of Hes. The characterization of synthesized Hes-Au/rGONCs were analysed using UV–vis spectrophotometry, FT-IR, Raman spectroscopy, X-ray diffraction analysis (XRD), XPS, HPLC, SEM, EDX and HR-TEM. The absence of vibrations at 1516 and 1381 cm−1 shows the involvement of hydroxyl groups of phenols and enols in anchoring Au on the surface of rGO. In XRD, the planes at (111), (200), (220) and (311) revealed the face centered cubic (fcc) crystalline structure of gold nanoparticles that were functionalized on rGO nanosheets. Hes-Au/rGONCs synthesised produced a highly negative zeta potential of -36.44 mV due to their stability. The Hes-rGO/Au-NPs were analysed for their surface morphology by SEM. The HR-TEM micrographs exhibited uniform distribution and homogenous spherical shaped AuNPs with an average size of 21.37±5.7 nm on rGO sheets. The bio reduction percentage was calculated as 98.86% by using HPLC. The inhibitory concentration (IC50) of free-Hes and nanocomposites were 157.57 and 38.41 µM, respectively. The Hes-Au/rGONCs possess effective bactericidal activity against gram positive bacterial species than against gram negative bacterial strains. The resazurin dye assay confirms the MIC values of Hes-Au/rGONCs. Hereby, the outcome of these studies suggested that the fabricated Hes-Au/rGONCs have potential biomedical applications.

In vitro assessment of the immobilized mannanase enzyme against infection-causing Candida.

Background: Developing an effective treatment for fungal infections is among contemporary medicine's challenges. In this study we aimed to eradicate mannan in pathogenic Candidae's cell walls using a nontoxic method, mannanase. Materials & Methods: We investigated the in vitro antifungal activities of mannanase immobilized on zinc oxide nanoparticles (ZnONps) and reduced graphene oxide nanoparticles (RGONps), as well as therapeutics against Candidae. Mannanase was purified from Bacillus invictae (activity: 5.15EU/ml;range: 60-80%) and then immobilized it to ZnO and RGO to enhance its effectiveness. Results: Mannanase immobilized on ZnONps had the highest activity, with a value of 4.97EU/ml, more effective than amphotericin-B. However, it could not reach the inhibition rates of other antifungals. Conclusion: Mannanase immobilized on ZnONps could be an effective fungicide for Candida biocontrol.

An impedimetric immunosensor based on chitosan-Au nanoparticles-reduced graphene oxide nanosheet composite modified PG electrode for detection of brain natriuretic peptide.

The online version contains supplementary material available at 10.1007/s13205-023-03704-x.

Electrochemical Determination of Acetaminophen with a FeNi Nanoparticle Reduced Graphene Oxide (rGO) Nanocomposite and Differential Pulse Voltammetry (DPV)

Acetaminophen (AP) is one of the most commonly used antipyretics. Accurate and efficient determination of its concentration is of great significance to human health. In this work, FeNi alloy nanoparticles and reduced graphene oxide (rGO) were compounded by an ultrasonic method to obtain FeNi/rGO nanocomposites. The nanocomposites were analyzed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and cyclic voltammetry (CV). Due to the catalytic activity of FeNi alloy nanoparticles and the synergy between the high specific surface area and conductivity of reduced graphene oxice (rGO), a FeNi/rGO nanocomposite showed excellent electrocatalysis for acetaminophen determination. With differential pulse voltammetry (DPV) as the analytical method, the linear range for acetaminophen is from 1 to 100 and 100 to 3,000 μM with a limit of detection (LOD) equal to 0.3 μM. Moreover, the sensor also has good reproducibility and selectivity with high recoveries in practical analysis.

Rheological studying the effect of reduced graphene oxide nanoparticles on the creep behavior of epoxy coating of pipelines: Part I—Constitutive equations

AbstractIn this article, the creep behavior of pure and reinforced epoxy‐polyamine samples with different amounts of reduced graphene oxide (RGO) at two temperature levels of 28 and 40°C is investigated experimentally and analytically to develop the creep‐associated constitutive equations. Mechanical properties and creep behavior of samples are obtained by carrying out tensile and creep tests at different stress levels. The Burgers model and modified Burgers model are used to investigate the creep behavior of pure and reinforced epoxy. The experimental results show that the addition of 0.5% RGO increases the yield strength of the samples by 51% and the maximum strain by 20%. Also, by considering the production costs of reinforced epoxy, the sample reinforced with 0.5 wt% graphene is selected as the optimum added value of RGO nanoparticles which results in the desired failure load and creep resistance. Additionally, it is discovered that the modified Burgers model, albeit having a larger computing cost, can accurately simulate samples' creep behavior. Furthermore, Fourier transform infrared spectroscopy and scanning electron microscopy analyses are performed on the samples and it is found that the addition of RGO particles improves the microstructure of the reinforced samples.