Search Results (4,748)

In this work, we report a study of a zinc sulfide (ZnS) nanocrystal and reduced graphene oxide (RGO) nanocomposite-based non-enzymatic uric acid biosensor. ZnS nanocrystals with different morphologies were synthesized through a hydrothermal method, and both pure nanocrystals and related ZnS/RGO were characterized with SEM, XRD and an absorption spectrum and resistance test. It was found that compared to ZnS nanoparticles, the ZnS nanoflakes had stronger UV light absorption ability at the wavelength of 280 nm of UV light. The RGO significantly enhanced the electron transfer efficiency of the ZnS nanoflakes, which further led to a better photoelectrochemical property of the ZnS/RGO nanocomposites. The ZnS nanoflake/RGO nanocomposite-based biosensor showed an excellent uric acid detecting sensitivity of 534.5 μA·cm⁻²·mM⁻¹ in the linear range of 0.01 to 2 mM and a detection limit of 0.048 μM. These results will help to improve non-enzymatic biosensor properties for the rapid and accurate clinical detection of uric acid. Full article

A novel sandwich-type electrochemical aptasensor based on supramolecularly immobilized affinity bioreceptor was prepared via host–guest interactions. This method utilizes an adamantane-modified, target-responsive hairpin DNA aptamer as a capture molecular receptor, along with a perthiolated β-cyclodextrin (CD) covalently attached to a gold-modified electrode surface as the transduction element. The proposed sensing strategy employed an enzyme-modified aptamer as the signalling element to develop a sandwich-type aptasensor for detecting prostate-specific antigen (PSA). To achieve this, screen-printed carbon electrodes (SPCEs) with electrodeposited reduced graphene oxide (RGO) and gold nanoferns (AuNFs) were modified with the CD derivative to subsequently anchor the adamantane-modified anti-PSA aptamer via supramolecular associations. The sensing mechanism involves the affinity recognition of PSA molecules on the aptamer-enriched electrode surface, followed by the binding of an anti-PSA aptamer–horseradish peroxidase complex as a labelling element. This sandwich-type arrangement produces an analytical signal upon the addition of H₂O₂ and hydroquinone as enzyme substrates. The aptasensor successfully detected the biomarker within a concentration range of 0.5 ng/mL to 50 ng/mL, exhibiting high selectivity and a detection limit of 0.11 ng/mL in PBS. Full article

Recently, the accumulation of Amyloid Beta (Aβ) in the brain has been linked to the development of Alzheimer’s disease (AD) through the formation of aggregated plaques and neurofibrillary tangles (NFTs). Although carbon nanoparticles were previously shown as having a potential to address AD, the interactions of Aβ with such nanoparticles have not been studied extensively. In this work, molecular dynamic simulations are utilized to simulate the interactions between a single atomic layer of graphene oxide (GO) and a 12-monomer Aβ fibril. These interactions are further compared to those between GO and five individual monomers of Aβ to further understand the conformational changes in Aβ as an individual monomer and as a component of the Aβ fibril. It was found that out of the 42 residues of the Aβ monomers, residues 27–42 are the most affected by the presence of GO. Furthermore, stability analysis through RMSD, conformational energies and salt bridges, along with nonbonding energy, illustrate that Aβ–Aβ interactions were successfully interrupted and dismantled by GO. Overall, the differences in the interactions between monomeric Aβ consisting of five monomers with GO, an Aβ fibril with GO, and control Aβ monomers among themselves, helped elucidate the potential that GO has to disentangle the Aβ tangles, both in case of individual monomers forming a cluster and as part of the Aβ fibril. Full article

Enhancing the corona resistance of epoxy resin (EP) is crucial for ensuring the reliable operation of electrical equipment and power systems, and the incorporation of inorganic nanofillers into epoxy resin has shown significant potential in achieving this. In this study, functionalized graphene oxide (KHGO) was synthesized via a sol-gel method to enhance the corona resistance of EP with electrochemical impedance spectroscopy (EIS) used to assess the properties of KHGO/EP composites. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) verified the successful grafting of epoxy groups onto the GO surface. The thermal conductivity and stability of the KHGO/EP composite initially increased with KHGO content but declined when the content exceeded 1.2 wt.%. Positron annihilation lifetime spectroscopy (PALS) indicated that KHGO improved interfacial compatibility with EP compared to GO, with agglomeration occurring when KHGO content exceeded a threshold value (1.2 wt.%). EIS analysis revealed that the corona resistance of the KHGO/EP composite was optimal at a filler content of 0.9 wt.%. After corona treatment, the saturation water uptake of the 0.9 wt.% KHGO/EP composite decreased by 15% compared to pure EP with its porosity reduced to just 1/40th of that of pure EP. This study underscores that well-dispersed KHGO/EP composite exhibits excellent corona resistance property suggesting the potential for industrial applications in high-voltage equipment insulation. Full article

Currently, one of the topical directions in the field of production and application of graphene-like nanostructures is the use of renewable natural raw materials, which have unlimited resources for an economically efficient large-scale yield of a product with environmental safety. In this regard, we present the production of graphene oxide (GO) from a renewable natural raw material of plant biomass, birch activated carbon (BAC), and a comparison of the obtained physicochemical, mechanical, and electrical properties of birch activated carbon–graphene oxide (BAC–GO) and graphite–graphene oxide (G–GO) synthesized from the initial materials, BAC and graphite (G). Results obtained from this study confirm the successful oxidation of BAC, which correlates well with the physical–chemical dates of the G–GO and BAC–GO samples. Change in data after the oxidation of graphite and BAC was facilitated by the structure of the starting materials and, presumably, the location and content of functional oxygen-containing groups in the G–GO and BAC–GO chains. Based on the results, the application of a cost-effective, eco-friendly colloidal solution of nanodispersed BAC–GO from a plant biomass-based high-quality resource for producing large-scale nanostructured graphene is validated which has potential applicability in nanoelectronics, medicine, and other fields. Full article

Despite considerable progress, high-performing durable catalysts operating under large current densities (i.e., >1000 mA/cm²) are still lacking. To discover platinum group metal-free (PGM-free) electrocatalysts for sustainable energy, our research involves investigating layered topological magnetic materials (semiconducting ferromagnets) as highly efficient electrocatalysts for the hydrogen evolution reaction under high current densities and establishes the novel relations between structure and electrochemical property mechanisms. The materials of interest include transition metal trihalides, i.e., CrCl₃, VCl₃, and VI₃, wherein a structural unit, the layered structure, is formed by Cr (or V) atoms sandwiched between two halides (Cl or I), forming a tri-layer. A few layers of quantum crystals were exfoliated (~50−60 nm), encapsulated with graphene, and electrocatalytic HER tests were conducted in acid (0.5M H₂SO₄) and alkaline (1M KOH) electrolytes. We find a reasonable HER activity evolved requiring overpotentials in a range of 30–50 mV under 10 mA cm⁻² and 400−510 mV (0.5M H₂SO₄) and 280−500 mV (1M KOH) under −1000 mA cm⁻². Likewise, the Tafel slopes range from 27 to 36 mV dec⁻¹ (Volmer–Tafel) and 110 to 190 mV dec⁻¹ (Volmer–Herovsky), implying that these mechanisms work at low and high current densities, respectively. Weak interlayer coupling, spontaneous surface oxidation, the presence of a semi-oxide subsurface (e.g., O–CrCl₃), intrinsic Cl (or I) vacancy defects giving rise to in-gap states, electron redistribution (orbital hybridization) affecting the covalency, and sufficiently conductive support interaction lowering the charge transfer resistance endow the optimized adsorption/desorption strength of H^* on active sites and favorable electrocatalytic properties. Such behavior is expedited for bi-/tri-layers while exemplifying the critical role of quantum nature electrocatalysts with defect sites for industrial-relevant conditions. Full article

The fabrication process of reduced graphene oxide depends on many factors (e.g., graphite precursor, methods of oxidation, reduction, and exfoliation) which have a significant influence on the properties of this material. Therefore, their selection is not easy due to the large number of possible combinations of these factors. To overcome this problem, we proposed to use a multivariate analysis of variance method of finding associations between the qualitative type of independent variables and the quantitative type of dependent variable. Using ANOVA, we showed that the combination (interaction) of these variables is more important than the individual influence of the variables on the fabricated rGO. Knowing how the particular variables and their combinations affect the properties of rGO, it is easier to plan the fabrication process of this material. In this paper, we analyzed the number of oxide layers and designated the most promising oxides in terms of sensor gas application. Independently, we fabricated chemiresistor sensors and studied their response to NO₂ in the analyzed atmosphere. We were able to combine the experimental results with statistical analysis indicating which oxidation methods and which graphite precursors will provide the best sensitivity. Full article

One-dimensional lithium-ion transport channels in lithium iron phosphate (LFP) used as a cathode in lithium-ion batteries (LIBs) result in low electrical conductivity and reduced electrochemical performance. To overcome this limitation, three-dimensional plasma-treated reduced graphene oxide (rGO) was synthesized in this study and used as an additive for LFP in LIB cathodes. Graphene oxide was synthesized using Hummers’ method, followed by mixing with LFP, lyophilization, and plasma treatment to obtain LFP@rGO. The plasma treatment achieved the highest degree of reduction and porosity in rGO, creating ion transfer channels. The structure of LFP@rGO was verified through scanning electron microscopy (SEM) analysis, which demonstrated that incorporating 10.0 wt% of rGO into LFP resulted in successful coverage by the rGO layer, forming LFP@rGO-10. In half-cell tests, LFP@rGO-10 exhibited a specific capacity of 142.7 mAh g⁻¹ at the 1.0 C-rate, which is higher than that of LFP. The full-cell exhibited 86.8% capacity retention after 200 cycles, demonstrating the effectiveness of rGO in enhancing the performance of LFP as an LIB cathode material. The outstanding efficiency and performance of the LFP@rGO-10//graphite cell highlight the promising potential of rGO-modified LFP as a cathode material for high-performance LIBs, providing both increased capacity and stability. Full article

The use of nanoparticles in the industry carries the risk of their release into the environment. Based on the presumption that the primary graphene oxide (GO) toxicity mechanism is reactive oxygen species production in the cell, the question arises as to whether well-known antioxidants can protect the cell or significantly reduce the effects of GO. This study focused on the possible remedial effect of vitamin C in Acheta domesticus intoxicated with GO for whole lives. The reproduction potential was measured at the level of Vitellogenin (Vg) gene expression, Vg protein expression, hatching success, and share of nutrition in the developing egg. There was no simple relationship between the Vg gene’s expression and the Vg protein content. Despite fewer eggs laid in the vitamin C groups, hatching success was high, and egg composition did not differ significantly. The exceptions were GO20 and GO20 + Vit. C groups, with a shift in the lipid content in the egg. Most likely, ascorbic acid impacts the level of Vg gene expression but does not affect the production of Vg protein or the quality of eggs laid. Low GO concentration in food did not cause adverse effects, but the relationship between GO toxicity and its concentration should be investigated more thoroughly. Full article

Background/Objectives: Peripheral nerve injuries (PNIs) are a debilitating problem, resulting in diminished quality of life due to the continued presence of both chronic and acute pain. The current standard of practice for the repair of PNIs larger than 10 mm is the use of autologous nerve grafts. Autologous nerve grafts have limitations that often result in outcomes that are not sufficient to remove motor and sensory impairments. Bio-mimetic nanocomposite scaffolds combined with mesenchymal stem cells (MSCs) represent a promising approach for PNIs. In this study, we investigated the potential of an electrospun wrap of polycaprolactone (PCL) + graphene oxide (GO), with and without xenogeneic human adipose tissue-derived MSCs (hADMSCs) to use as a platform for neural tissue engineering. Methods: We evaluated, in vitro and in vivo, the potential of the nerve wrap in providing support for axonal growth. To establish the rat sciatic nerve defect model, a 10 mm long limiting defect was created in the rat sciatic nerve of 18 Lewis rats. Rats treated with the nanocomposites were compared with autograft-treated defects. Gait, histological, and muscle analyses were performed after sacrifice at 12 weeks post-surgery. Results: Our findings demonstrate that hADMSCs had the potential to transdifferentiate into neural lineage and that the nanocomposite successfully delivered hADMSCs to the injury site. Histologically, we show that the PCL + GO nanocomposite with hADMSCs is comparable to the autologous nerve graft, to support and guide axonal growth. Conclusions: The novel PCL + GO nerve wrap and hADMSCs used in this study provide a foundation on which to build upon and generate future strategies for PNI repair. Full article

Graphene and MXenes have emerged as promising materials for gas sensing applications due to their unique properties and superior performance. This review focuses on the fabrication techniques, applications, and sensing mechanisms of graphene and MXene-based composites in gas sensing. Gas sensors are crucial in various fields, including healthcare, environmental monitoring, and industrial safety, for detecting and monitoring gases such as hydrogen sulfide (H₂S), nitrogen dioxide (NO₂), and ammonia (NH₃). Conventional metal oxides like tin oxide (SnO₂) and zinc oxide (ZnO) have been widely used, but graphene and MXenes offer enhanced sensitivity, selectivity, and response times. Graphene-based sensors can detect low concentrations of gases like H₂S and NH₃, while functionalization can improve their gas-specific selectivity. MXenes, a new class of two-dimensional materials, exhibit high electrical conductivity and tunable surface chemistry, making them suitable for selective and sensitive detection of various gases, including VOCs and humidity. Other materials, such as metal-organic frameworks (MOFs) and conducting polymers, have also shown potential in gas sensing applications, which may be doped into graphene and MXene layers to improve the sensitivity of the sensors. Full article

Integrating hyperthermia with conventional cancer therapies shows promise in improving treatment efficacy while mitigating their side effects. Nanotechnology-based hyperthermia, particularly using superparamagnetic iron oxide nanoparticles (SPIONs), offers a simplified solution for cancer treatment. In this study, we developed composites of SPION quantum dots (Fe₃O₄) with reduced graphene oxide (Fe₃O₄/RGO) using the coprecipitation method and investigated their potential application in magnetic hyperthermia. The size of Fe₃O₄ nanoparticles was controlled within the quantum dot range (≤10 nm) by varying the synthesis parameters, including reaction time as well as the concentration of ammonia and graphene oxide, where their biocompatibility was further improved with the inclusion of polyethylene glycol (PEG). These nanocomposites exhibited low cytotoxic effects on healthy cells (CHO-K1) over an incubation period of 24 h, though the inclusion of PEG enhanced their biocompatibility for longer incubation periods over 48 h. The Fe₃O₄/RGO composites dispersed in acidic pH buffer (pH 4.66) exhibited considerable heating effects, with the solution temperature increasing by ~10 °C within 5 min of exposure to pulsed magnetic fields, as compared to their dispersions in phosphate buffer and aqueous dimethylsulfoxide solutions. These results demonstrated the feasibility of using quantum dot Fe₃O₄/RGO composites for magnetic hyperthermia-based therapy to treat cancer, with further studies required to systematically optimize their magnetic properties and evaluate their efficacy for in vitro and in vivo applications. Full article

High electrical conductivity, along with high piezoresistive sensitivity and stretchability, are crucial for designing and developing nanocomposite strain sensors for damage sensing and on-line structural health monitoring of smart carbon fiber-reinforced polymer (CFRP) composites. In this study, the influence of the geometric features and loadings of carbon-based nanomaterials, including reduced graphene oxide (rGO) or carbon nanofibers (CNFs), on the tunable strain-sensing capabilities of epoxy-based nanocomposites was investigated. This work revealed distinct strain-sensing behavior and sensitivities (gauge factor, GF) depending on both factors. The highest GF values were attained with 0.13 wt.% of rGO at various strains. The stability and reproducibility of the most promising self-sensing nanocomposites were also evaluated through ten stretching/relaxing cycles, and a distinct behavior was observed. While the deformation of the conductive network formed by rGO proved to be predominantly elastic and reversible, nanocomposite sensors containing 0.714 wt.% of CNFs showed that new conductive pathways were established between neighboring CNFs. Based on the best results, formulations were selected for the manufacturing of pre-impregnated materials and related smart CFRP composites. Digital image correlation was synchronized with electrical resistance variation to study the strain-sensing capabilities of modified CFRP composites (at 90° orientation). Promising results were achieved through the incorporation of CNFs since they are able to form new conductive pathways and penetrate between micrometer-sized fibers. Full article

Cement-based composites (CBCs) are essential in the construction sector due to their cost-effectiveness, availability, and versatility, but they struggle with low tensile strength and poor heat resistance. Recent advancements have highlighted the potential of nanomaterials, particularly graphene oxide (GO), in enhancing the mechanical, thermal, and electrical properties of CBCs. This study aims to provide a comprehensive review of the incorporation of GO into cementitious composites, examining its impact on microstructure, mechanical properties, rheology, and durability; thus, a bibliometric review and scientometric analysis were conducted to thoroughly evaluate the existing literature. A total of 263 studies were selected for thorough study. It can be concluded that GO content acts as a pore filler, decreasing porosity by 23% and average pore size by 22%, while boosting compressive strength by up to 15% at a 0.05% concentration. It also enhances workability, stability, and resistance to chloride ingress, sulfate attack, alkali–silica reaction, and carbonation. Incorporating GO reduces cement consumption and carbon footprint, leading to more durable structures and supporting sustainable construction by efficiently utilizing waste materials. The optimal GO concentration for these benefits ranges from 0.03% to 0.1% by weight of cement, as higher concentrations may cause agglomeration. GO-modified cementitious materials are well suited for high-performance and durable applications, particularly in environments with chemical and mechanical stresses. Full article

This review explores the application of graphene-based materials (GBMs) in biomedicine, focusing on graphene oxide (GO) and its interactions with peptides and proteins. GO, a versatile nanomaterial with oxygen-containing functional groups, holds significant potential for biomedical applications but faces challenges related to toxicity and environmental impact. Peptides and proteins can be functionalized on GO surfaces through various methods, including non-covalent interactions such as π–π stacking, electrostatic forces, hydrophobic interactions, hydrogen bonding, and van der Waals forces, as well as covalent bonding through reactions involving amide bond formation, esterification, thiol chemistry, and click chemistry. These approaches enhance GO’s functionality in several key areas: biosensing for sensitive biomarker detection, theranostic imaging that integrates diagnostics and therapy for real-time treatment monitoring, and targeted cancer therapy where GO can deliver drugs directly to tumor sites while being tracked by imaging techniques like MRI and photoacoustic imaging. Additionally, GO-based scaffolds are advancing tissue engineering and aiding tissues’ bone, muscle, and nerve tissue regeneration, while their antimicrobial properties are improving infection-resistant medical devices. Despite its potential, addressing challenges related to stability and scalability is essential to fully harness the benefits of GBMs in healthcare. Full article