Innovative Approach to Accelerate Wound Healing: Synthesis and Validation of Enzymatically Cross-Linked COL-rGO Biocomposite Hydrogels.

In this study, an innovative conductive hybrid biomaterial was synthetized using collagen (COL) and reduced graphene oxide (rGO) in order for it to be used as a wound dressing. The hydrogels were plasticized with glycerol and enzymatically cross-linked with horseradish peroxidase (HRP). A successful interaction among the components was demonstrated by FTIR, XRD, and XPS. It was demonstrated that increasing the rGO concentration led to higher conductivity and negative charge density values. Moreover, rGO also improved the stability of hydrogels, which was expressed by a reduction in the biodegradation rate. Furthermore, the hydrogel's stability against the enzymatic action of collagenase type I was also strengthened by both the enzymatic cross-linking and the polymerization of dopamine. However, their absorption capacity, reaching values of 215 g/g, indicates the high potential of the hydrogels to absorb fluids. The rise of these properties positively influenced the wound closure process, achieving an 84.5% in vitro closure rate after 48 h. These findings clearly demonstrate that these original composite biomaterials can be a viable choice for wound healing purposes.

Nanocatalysis MoS2/rGO: An Efficient Electrocatalyst for the Hydrogen Evolution Reaction.

In this study, a systematic investigation of MoS2 nanostructure growth on a SiO2 substrate was conducted using a two-stage process. Initially, a thin layer of Mo was grown through sputtering, followed by a sulfurization process employing the CVD technique. This two-stage process enables the control of diverse nanostructure formations of both MoS2 and MoO3 on SiO2 substrates, as well as the formation of bulk-like grain structures. Subsequently, the addition of reduced graphene oxide (rGO) was examined, resulting in MoS2/rGO(n), where graphene is uniformly deposited on the surface, exposing a higher number of active sites at the edges and consequently enhancing electroactivity in the HER. The influence of the synthesis time on the treated MoS2 and also MoS2/rGO(n) samples is evident in their excellent electrocatalytic performance with a low overpotential.

NH3 Sensor Based on rGO-PANI Composite with Improved Sensitivity.

This work reports on a reduced graphene oxide and poly(aniline) composite (rGO-PANI), with rGO clusters inserted between PANI chains. These clusters were formed due the plasticizing effect of N-methyl-2-pyrrolidone (NMP) solvent, which was added during the synthesis. Further, this composite was processed as thin film onto an interdigitated electrode array and used as the sensitive layer for ammonia gas, presenting sensitivity of 250% at 100 ppm, a response time of 97 s, and a lowest detection limit of 5 ppm. The PANI deprotonation process, upon exposure to NH3, rGO, also contributed by improving the sensitivity due its higher surface area and the presence of carboxylic acids. This allowed for the interaction between the hydrogen of NH3 (nucleophilic character) and the -COOH groups (electrophilic character) from the rGO surface, thereby introducing a promising sensing composite for amine-based gases.

Comparison between hydroxyapatite/soapstone and hydroxyapatite/reduced graphene oxide composite coatings: Synthesis and property improvement.

Economic viability and eco-friendliness are important characteristics that make implants available to the population in a sustainable way. In this work, we evaluate the performance of a low-cost, widely available, and eco-friendly material (talc from soapstone) relative to reduced graphene oxide as reinforcement to brittle hydroxyapatite coatings. We employ a low-cost and straightforward technique, electrodeposition, to deposit the composite coatings on the titanium substrate. Corrosion, wear, and biocompatibility tests indicate that the reduced graphene oxide can be effectively replaced by talc without reducing the mechanical, anticorrosion, and biocompatible composite coatings properties. Our results indicate that talc from soapstone is a promising material for biomedical applications.

Self-Assembled and One-Step Synthesis of Interconnected 3D Network of Fe3O4/Reduced Graphene Oxide Nanosheets Hybrid for High-Performance Supercapacitor Electrode.

In the present work, we have synthesized three-dimensional (3D) reduced graphene oxide nanosheets (rGO NSs) containing iron oxide nanoparticles (Fe3O4 NPs) hybrids (3D Fe3O4/rGO) by one-pot microwave approach. Structural and morphological studies reveal that the as-synthesized Fe3O4/rGO hybrids were composed of faceted Fe3O4 NPs induced into the interconnected network of rGO NSs. The morphologies and structures of the 3D hybrids have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectrometer (XPS). The electrochemical studies were analyzed by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy, which demonstrate superior electrochemical performance as supercapacitors electrode application. The specific capacitances of 3D hybrid materials was 455 F g-1 at the scan rate of 8 mV s-1, which is superior to that of bare Fe3O4 NPs. Additionally, the 3D hybrid shows good cycling stability with a retention ratio of 91.4 after starting from ∼190 cycles up to 9600 cycles. These attractive results suggest that this 3D Fe3O4/rGO hybrid shows better performance as an electrode material for high-performance supercapacitors.

Layer-by-layer assembly of functionalized reduced graphene oxide for direct electrochemistry and glucose detection.

We report an electrochemical glucose biosensor made with layer-by-layer (LbL) films of functionalized reduced graphene oxide (rGO) and glucose oxidase (GOx). The LbL assembly using positively and negatively charged rGO multilayers represents a simple approach to develop enzymatic biosensors. The electron transport properties of graphene were combined with the specificity provided by the enzyme. rGO was obtained and functionalized using chemical methods, being positively charged with poly(diallyldimethylammonium chloride) to form GPDDA, and negatively charged with poly(styrene sulfonate) to form GPSS. Stable aqueous dispersions of GPDDA and GPSS are easily obtained, enabling the growth of LbL films on various solid supports. The use of graphene in the immobilization of GOx promoted Direct Electron Transfer, which was evaluated by Cyclic Voltammetry. Amperometric measurements indicated a detection limit of 13.4µmol·L(-1) and sensitivity of 2.47µA·cm(-2)·mmol(-1)·L for glucose with the (GPDDA/GPSS)1/(GPDDA/GOx)2 architecture, whose thickness was 19.80±0.28nm, as determined by Surface Plasmon Resonance (SPR). The sensor may be useful for clinical analysis since glucose could be detected even in the presence of typical interfering agents and in real samples of a lactose-free milk and an electrolyte solution to prevent dehydration.