Search Results (9,867)

Glioblastoma multiforme (GBM) is the most severe form of brain cancer and presents unique challenges to developing novel treatments due to its immunosuppressive milieu where receptors like programmed death ligand 1 (PD-L1) are frequently elevated to prevent an effective anti-tumor immune response. To potentially shift the GBM environment from being immunosuppressive to immune-enhancing, we engineered a novel nanovehicle from reduced graphene oxide quantum dot (rGOQD), which are loaded with the immunomodulatory drug resiquimod (R848) and conjugated with an anti-PD-L1 antibody (aPD-L1). The immunomodulatory rGOQD/R8/aPDL1 nanoparticles can actively target the PD-L1 on the surface of ALTS1C1 murine glioblastoma cells and release R848 to enhance the T-cell-driven anti-tumor response. From in vitro experiments, the PD-L1-mediated intracellular uptake and the rGOQD-induced photothermal response after irradiation with near-infrared laser light led to the death of cancer cells and the release of damage-associated molecular patterns (DAMPs). The combinational effect of R848 and released DAMPs synergistically produces antigens to activate dendritic cells, which can prime T lymphocytes to infiltrate the tumor in vivo. As a result, T cells effectively target and attack the PD-L1-suppressed glioma cells and foster a robust photothermal therapy elicited anti-tumor immune response from a syngeneic mouse model of GBM with subcutaneously implanted ALTS1C1 cells. Full article

The study of novel materials for H₂ storage is essential to consolidate the hydrogen as a clean energy source. In this sense, the H₂ adsorption on Pd_4-nNi_n (n = 0–3) clusters embedded on pyridinic-type N-doped graphene (PNG) was investigated using density functional theory calculations. First, the properties of Pd_4-nNi_n (n = 0–3) clusters embedded on PNG were analyzed in detail. Then, the H₂ adsorption on these composites was computed. The E_int between the Pd_4-nNi_n (n = 0–3) clusters and the PNG was greater than that computed in the literature for Pd-based systems embedded on pristine graphene. Consequently, it was deduced that PNG can more significantly stabilize the Pd_4-nNi_n (n = 0–3) clusters. The analyzed composites exhibited a HOMO–LUMO gap less than 1 eV, indicating good reactivity. Based on the E_ads of H₂ on Pd_4-nNi_n (n = 0–3) clusters embedded on PNG, it was observed that the analyzed systems meet the standards set by the DOE. Therefore, these composites can be viable alternatives for hydrogen storage. Full article

Simple and scalable production of micro-supercapacitors (MSCs) is crucial to address the energy requirements of miniature electronics. Although significant advancements have been achieved in fabricating MSCs through solution-based printing techniques, the realization of high-performance MSCs remains a challenge. In this paper, graphene-based MSCs with a high power density were prepared through screen printing of aqueous conductive inks with appropriate rheological properties. High electrical conductivity (2.04 × 10⁴ S∙m⁻¹) and low equivalent series resistance (46.7 Ω) benefiting from the dense conductive network consisting of the mesoporous structure formed by graphene with carbon black dispersed as linkers, as well as the narrow finger width and interspace (200 µm) originating from the excellent printability, prompted the fully printed MSCs to deliver high capacitance (9.15 mF∙cm⁻²), energy density (1.30 µWh∙cm⁻²) and ultrahigh power density (89.9 mW∙cm⁻²). Notably, the resulting MSCs can effectively operate at scan rates up to 200 V∙s⁻¹, which surpasses conventional supercapacitors by two orders of magnitude. In addition, the MSCs demonstrate excellent cycling stability (91.6% capacity retention and ~100% Coulombic efficiency after 10,000 cycles) and extraordinary mechanical properties (92.2% capacity retention after 5000 bending cycles), indicating their broad application prospects in flexible wearable/portable electronic systems. Full article

Graphene/copper composites are promising in electronic and energy fields due to their superior conductivity, but microstructure control during thermal mechanical processing (TMP) remains a crucial issue for the manufacturing of high-performance graphene/copper composites. In this study, the hot deformation behavior of graphene/copper composites was investigated by isothermal compression tests at deformation temperatures of 700~850 °C and strain rates of 0.01~10 s⁻¹, and a constitutive equation based on the Arrhenius model and hot processing map was established. Results demonstrate that the deformation mechanism of the graphene/copper composites mainly involves dynamic recrystallization (DRX), and such DRX-mediated deformation behavior can be accurately described by the established Arrhenius model. In addition, it was found that the strain rate has a stronger impact on the DRX grain size than the deformation temperature. The optimum deformation temperature and strain rate were determined to be 800 °C and 1 s⁻¹, respectively, with which a uniform microstructure with fine grains can be obtained. Full article

Graphene-based materials (GBMs) are a prospective material of choice for rechargeable battery electrodes because of their unique set of qualities, which include tunable interlayer channels, high specific surface area, and strong electrical conductivity characteristics. The market for commercial rechargeable batteries is now dominated by lithium-ion batteries (LIBs). One of the primary factors impeding the development of new energy vehicles and large-scale energy storage applications is the safety of LIBs. Zinc-based rechargeable batteries have emerged as a viable substitute for rechargeable batteries due to their affordability, safety, and improved performance. This review article explores recent developments in the synthesis and advancement of GBMs for rechargeable zinc–air batteries (ZABs) and common graphene-based electrocatalyst types. An outlook on the difficulties and probable future paths of this extremely promising field of study is provided at the end. Full article

Density functional theory and a semi-empirical quantum chemical approach were used to evaluate the photocatalytic efficiency of ceria (CeO₂) combined with reduced graphene oxide (rGO) and graphene (GP) for degrading methylene blue (MB). Two main aspects were examined: the adsorption ability of rGO and GP for MB, and the separation of photogenerated electrons and holes in CeO₂/rGO and CeO₂/GP. Our results, based on calculations of the adsorption energy, population analysis, bond strength index, and reduced density gradient, show favorable energetics for MB adsorption on both rGO and GP surfaces. The process is driven by weak, non-covalent interactions, with rGO showing better MB adsorption. A detailed analysis involving parameters like fractional occupation density, the centroid distance between molecular orbitals, and the Lewis acid index of the catalysts highlights the effective charge separation in CeO₂/rGO compared to CeO₂/GP. These findings are crucial for understanding photocatalytic degradation mechanisms of organic dyes and developing efficient photocatalysts. Full article

The burning of Ethylene–Propylene–Diene Monomer (EPDM) rubber generates substantial smoke, posing a severe threat to the environment and personal safety. Considering the growing emphasis on safety and environmental protection, conventional non-smoke-suppressing flame retardants no longer satisfy the present application requirements. Consequently, there is an urgent need to develop a novel flame retardant capable of suppressing smoke formation while providing flame retardancy. Sepiolite (SEP), a porous silicate clay mineral abundant in silica and magnesium, exhibits notable advantages in the realm of flame retardancy and smoke suppression. This research focuses on the synthesis of two highly efficient flame-retardant smoke suppression systems, namely AEGS and PEGS, using Enteromorpha (EN), graphene (GE), sepiolite (SEP), ammonium polyphosphate (APP), and/or piperazine pyrophosphate (PPAP). The studied flame-retardant systems were then applied to EPDM rubber and the flame-retardant and smoke suppression abilities of EPDM/AEGS and EPDM/PEGS composites were compared. The findings indicate that the porous structure of sepiolite plays a significant role in reducing smoke emissions for EPDM composites during combustion. Full article

In the study, a hybrid lubricant was prepared by introducing graphene into a polyphosphate lubricant. In the tribological test of a steel/steel friction pair at the high temperature of 800 °C, the addition of a small proportion of graphene significantly enhances the lubrication performance of polyphosphate at elevated temperatures. The coefficient of friction and the wear were obviously held down while the surface quality of the high-temperature friction pair was enhanced effectively with the graphene-strengthened polyphosphate lubricant, compared with the dry sliding condition. Through scanning electron microscopy and Raman spectroscopy analysis, the formation mechanism of tribofilm and the antiwear performance of the hybrid lubricant are further explained. This lubricant effectively combines the advantages of both; the combination of polyphosphate melted at elevated temperature with graphene and metal surfaces ensures the self-sealing of the friction contact area and brings better high-temperature oxidation resistance. At the same time, the presence of graphene provides excellent strength to the friction film and ensures the anti-wear and wear-resistant performance of the lubricant at high temperatures. Full article

Exfoliated graphite (ExG) embedded in a polymeric matrix represents an accessible, cost-effective, and sustainable method for generating nanosized graphite-based polymer composites with multifunctional properties. This review article analyzes diverse methods currently used to exfoliate graphite into graphite nanoplatelets, few-layer graphene, and polymer-assisted graphene. It also explores engineered methods for small-scale pilot production of polymer nanocomposites. It highlights the chemistry involved during the graphite intercalation and exfoliation process, particularly emphasizing the interfacial interactions related to steric repulsion forces, van der Waals forces, hydrogen bonds, π-π stacking, and covalent bonds. These interactions promote the dispersion and stabilization of the graphite derivative structures in polymeric matrices. Finally, it compares the enhanced properties of nanocomposites, such as increased thermal and electrical conductivity and electromagnetic interference (EMI) shielding applications, with those of neat polymer materials. Full article

Shale formations present significant challenges to traditional drilling fluids due to fluid infiltration, cuttings dispersion, and shale swelling, which can destabilize the wellbore. While oil-based drilling fluids (OBM) effectively address these concerns about their environmental impact, their cost limits their widespread use. Recently, nanomaterials (NPs) have emerged as a promising approach in drilling fluid technology, offering an innovative solution to improve the efficiency of water-based drilling fluids (WBDFs) in shale operations. This study evaluates the potential of utilizing modified silica nanocomposite and graphene nanopowder to formulate a nanoparticle-enhanced water-based drilling fluid (NP-WBDF). The main objective is to investigate the impact of these nanoparticle additives on the flow characteristics, filtration efficiency, and inhibition properties of the NP-WBDF. In this research, a silica nanocomposite was successfully synthesized using emulsion polymerization and analyzed using FTIR, PSD, and TEM techniques. Results showed that the silica nanocomposite exhibited a unimodal particle size distribution ranging from 38 nm to 164 nm, with an average particle size of approximately 72 nm. Shale samples before and after interaction with the graphene nanopowder WBDF and the silica nanocomposite WBDF were analyzed using scanning electron microscopy (SEM). The NP-WBM underwent evaluation through API filtration tests (LTLP), high-temperature/high-pressure (HTHP) filtration tests, and rheological measurements conducted with a conventional viscometer. Experimental results showed that the silica nanocomposite and the graphene nanopowder effectively bridged and sealed shale pore throats, demonstrating superior inhibition performance compared to conventional WBDF. Post adsorption, the shale surface exhibited increased hydrophobicity, contributing to enhanced stability. Overall, the silica nanocomposite and the graphene nanopowder positively impacted rheological performance and provided favorable filtration control in water-based drilling fluids. Full article

Due to the clinical similarities between pulmonary embolism (PE) and myocardial infarction (MI), physicians often encounter challenges in promptly distinguishing between them, potentially missing the critical window for the correct emergency response. This paper presents a biosensor, termed the PEMI biosensor, which is designed for the identification and quantitative detection of pulmonary embolism or myocardial infarction. The surface of the working electrode of the PEMI biosensor was modified with graphene oxide and silk fibroin to immobilize the mixture of antibodies. Linear sweep voltammetry was employed to measure the current-to-potential mapping of analytes, with the calculated curvature serving as a judgment index. Experimental results showed that the curvature exhibited a linear correlation with the concentration of antigen FVIII, and a linear inverse correlation with the concentration of antigen cTnI. Given that FVIII and cTnI coexist in humans, the upper and lower limits were determined from the curvatures of a set of normal concentrations of FVIII and cTnI. An analyte with a curvature exceeding the upper limit can be identified as pulmonary embolism, while a curvature falling below the lower limit indicates myocardial infarction. Additionally, the further the curvature deviates from the upper or lower limits, the more severe the condition. The PEMI biosensor can serve as an effective detection platform for physicians. Full article

Titanium alloys are difficult to machine and have poor tribological properties. Nanoparticles have good cooling and lubricating properties, which can be used in metal cutting fluid. The lubrication characteristics of the two-dimensional materials Ti₃C₂T_X MXene and graphene oxide in water-based fluid for titanium alloys were comparatively investigated in this paper. Graphene oxide had smaller friction coefficients and wear volume than Ti₃C₂T_X MXene nanofluid. As to the mechanism, MXene easily formed TiO₂ for the tribo-chemical reaction, which accelerated wear. Moreover, GO nanofluid can form a more uniform and stable friction layer between the frictional interface, which reduces the friction coefficient and decreases the adhesive wear. The effects of different surfactants on the lubricating properties of MXene were further investigated. It was found that the cationic surfactant Hexadecyl trimethyl ammonium chloride (1631) had the lowest friction coefficient and anti-wear properties for the strong electrostatic attraction with MXene nanoparticles. The results of this study indicate that 2D nanoparticles, especially graphene oxide, could improve the lubricating properties of titanium alloys. It provides insight into the application of water-based nanofluids for difficult-to-machine materials to enhance surface quality and cutting efficiency. The developed nanofluid, which can lubricate titanium alloys, effectively has very broad applications in prospect. Full article

The absence of adequate methods for hydrogen storage has prevented the implementation of hydrogen as a major source of energy. Graphene-based materials have been considered for use as solid hydrogen storage, because of graphene’s high specific surface area. However, these materials alone do not meet the hydrogen storage standard of 6.5 wt.% set by the United States Department of Energy (DOE). They can, however, be easily modified through either decoration or doping to alter their chemical properties and increase their hydrogen storage capacity. This review is a compilation of various published reports on this topic and summarizes results from theoretical and experimental studies that explore the hydrogen storage properties of metal-modified graphene materials. The efficacy of alkali, alkaline earth metal, and transition metal decoration is examined. In addition, metal doping to further increase storage capacity is considered. Methods for hydrogen storage capacity measurements are later explained and the properties of an effective hydrogen storage material are summarized. Full article

A ZnO-Graphene oxide nanocomposite (Z-G) was prepared in order to exploit the biomedical features of each component in a single anticancer material. This was achieved by means of an environmentally friendly synthesis, taking place at a low temperature and without the involvement of toxic reagents. The product was physicochemically characterized. The ZnO-to-GO ratio was determined through thermogravimetric analysis, while scanning electron microscopy and transmission electron microscopy were used to provide insight into the morphology of the nanocomposite. Using energy-dispersive X-ray spectroscopy, it was possible to confirm that the graphene flakes were homogeneously coated with ZnO. The crystallite size of the ZnO nanoparticles in the new composite was determined using X-ray powder diffraction. The capacity of Z-G to enhance the toxicity of the anticancer drug Paclitaxel towards breast cancer cells was assessed via a cell viability study, showing the remarkable anticancer activity of the obtained system. Such results support the potential use of Z-G as an anticancer agent in combination with a common chemotherapeutic like Paclitaxel, leading to new chemotherapeutic formulations. Full article

A novel graphene-based composite, 5-methyl-1,3,4-thiadiazol-2-amine (MTA) covalently functionalized graphene oxide (GO-MTA), was rationally developed and used for the selective sorption of Ga³⁺ from aqueous solutions, showing a higher adsorption capacity (48.20 mg g⁻¹) toward Ga³⁺ than In³⁺ (15.41 mg g⁻¹) and Sc³⁺ (~0 mg g⁻¹). The adsorption experiment’s parameters, such as the contact time, temperature, initial Ga³⁺ concentration, solution pH, and desorption solvent, were investigated. Under optimized conditions, the GO-MTA composite displayed the highest adsorption capacity of 55.6 mg g⁻¹ toward Ga³⁺. Moreover, a possible adsorption mechanism was proposed using various characterization methods, including scanning electron microscopy (SEM) equipped with X-ray energy-dispersive spectroscopy (EDS), elemental mapping analysis, Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Ga³⁺ adsorption with the GO-MTA composite could be better described by the linear pseudo-second-order kinetic model (R² = 0.962), suggesting that the rate-limiting step may be chemical sorption or chemisorption through the sharing or exchange of electrons between the adsorbent and the adsorbate. Importantly, the calculated q_e value (55.066 mg g⁻¹) is closer to the experimental result (55.60 mg g⁻¹). The well-fitted linear Langmuir isothermal model (R² = 0.972~0.997) confirmed that an interfacial monolayer and cooperative adsorption occur on a heterogeneous surface. The results showed that the GO-MTA composite might be a potential adsorbent for the enrichment and/or separation of Ga³⁺ at low or ultra-low concentrations in aqueous solutions. Full article