A Brief Review: The Use of L-Ascorbic Acid as a Green Reducing Agent of Graphene Oxide

DIW 3D printing of well-interconnected hierarchically porous microlattice for ultrasensitive photoelectrochemical sensing

Endowing channel-interconnected photoelectrode with prominent light-absorbing and analyte-trapping is pivotal but challenging for implementing high-performance photoelectrochemical sensing system. Herein, we demonstrated an effective and controllable direct ink writing (DIW) 3D printing coupled with molecular imprinting technology for consistently fabricating microlattice-shaped photoelectrochemical sensor, with multiscale well-interconnected channels created by accessible alliance of regular macrochannels originated from layer-by-layer assembly of printed filaments and abundant microchannels built by jointing molecule-recognized polyaniline (PANI), photoactive TiO2 and conductive graphene (G) nanosheets within filaments. The unique structure merit facilitated ready spreading of incident light into the sensor interior, and meanwhile enabled rapid diffusion/infiltration of analytes onto all specificity binding sites situated inside the sensor, thereby allowing light absorbance and analyte adsorption at a high level. As a result, the 3D-printed molecularly imprinted photoelectrochemical sensor displayed impressive monitoring capability for urea, with rapid response, low detection limit (2 μM), wide linear range (10-700 μM), exceptional selectivity and working stability. This work opens up a promising route for architecting advanced photoelectrochemical devices to cater to highly sensitive and selective sensing.

Lasso Model-Based Optimization of CNC/CNF/rGO Nanocomposites

This study explores the use of citric acid and L-ascorbic acid as reducing agents in CNC/CNF/rGO nanocomposite fabrication, focusing on their effects on electrical conductivity and mechanical properties. Through comprehensive analysis, L-ascorbic acid showed superior reduction efficiency, producing rGO with enhanced electrical conductivity up to 2.5 S/m, while citric acid offered better CNC and CNF dispersion, leading to higher mechanical stability. The research employs an advanced optimization framework, integrating regression models and a neural network with 30 hidden layers, to provide insights into composition-property relationships and enable precise material tailoring. The neural network model, trained on various input variables, demonstrated excellent predictive performance, with R2 values exceeding 0.998. A LASSO model was also implemented to analyze variable impacts on material properties. The findings, supported by machine learning optimization, have significant implications for flexible electronics, smart packaging, and biomedical applications, paving the way for future research on scalability, long-term stability, and advanced modeling techniques for these sustainable, multifunctional materials.

Fabrication of 3D Graphene-Silk Elastic Aerogels for Sustainable and Efficient Removal of Organic Dyes from an Aqueous Medium

Water pollution by dyes is a serious environmental issue of modern society that needs to be addressed effectively. Herein, a promising adsorbent, i.e., 3D composite aerogel, was developed by using reduced graphene oxide and silk fibroin (rGO-SF) via hydrothermal and freeze-drying techniques. The efficiency of the prepared aerogel toward methylene blue (MB) dye adsorption was explored in batch adsorption experiments. A study revealed the adsorption capacity of rGO-SF120 as 249.89 mg/g toward methylene blue (MB) dye. The aerogel also selectively adsorbs MB over other dyes, such as rhodamine B (RhB) and methylene orange (MO). The adsorption process was mainly chemical (as data fitted well to both pseudo-second-order and Elovich kinetic models) and followed the Langmuir model, indicating that it formed a single layer of dye on its surface. Overall, the rGO-SF120 aerogel is an effective and potential candidate for treating dye-loaded water with high efficiency.

Unveiling a novel mechanism: Reduction of graphene oxide by Lysinibacillus sp. through secretion of l-ascorbic acid

The graphene oxide (GO) reduction by microorganisms has garnered considerable interest, yet the specific mechanisms underlying the bacteria secretion of reducing substances for GO reduction remain unclear. This study aims to learn that bacterial extracellular components can reduce graphene oxide through direct (contacting GO) and indirect (not contacting GO) reduction experiments. The subsequent investigation focused on identifying the specific substances secreted by bacteria capable of GO reduction. The results of non-targeted metabolomics revealed differential expression of cacid (L-AA) demonstrates a significant up-regulation. The further experiment involved the supplementation of L-AA in the reduction system of Lysinibacillus sp. with GO, demonstrating enhanced reduction efficacy, with the ID/IG ratio of reduced graphene oxide (rGO) increasing to 1.073 after 4 d of reduction with 0.5 g L-1 L-AA. Therefore, the mediation of GO reduction by L-AA secreted by Lysinibacillus sp. is proposed as a viable mechanism, offering novel insights into microbial GO reduction.

Optimizing Green Synthesis of Hydrotalcite - Silver Nanoparticles using Syzygium Nervosum based Reducing Agent

Hydrotalcite-silver (HT-Ag) nanoparticles have been involved in various daily crucial applications, such as antibacterial, photocatalytic, adsorption, etc. There are many approaches to synthesizing silver nanoparticles (AgNPs) decorated on hydrotalcite (HT) surface and the most used approach is using a strong reducing agent. Thus, affordable but effective "green" reducing agents - Syzygium nervosum leaf extract, are taken into account in this work to solve several issues related to chemical reducing agents. This work aimed to assess the effect of Syzygium nervosum leaf extract as a reducing agent for green synthesis of AgNPs on HT through an optimizing process using response surface methodology (RSM) and the Box-Benken model. The optimal conditions for the synthesis of AgNPs on HT include a reaction time of 6.15 hours, a reaction temperature of 50 °C, and the ratio of diluted Syzygium nervosum leaf extract to reduce AgNO3 of 50.37 mL/mg. Under the optimal conditions, the yield of the reduction reaction reached 77.54 %, close to the theoretical value of 76.97 %. The optimization model was suitable for the experiment data. Besides, the morphology, density, and characteristics of AgNPs on the surface of HT layers have been determined by using Ultraviolet-visible spectroscopy, Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HR-TEM), selected area diffraction, X-ray diffraction, Dynamic light scattering (DLS), Infrared (IR) spectroscopy, Fluorescence emission spectroscopy (FE), Brunauer-Emmett-Teller (BET) methods. The spherical AgNPs were synthesized successfully on the surface of HT with the average particle size of 13.0±1.1 nm. Interestingly, HT-Ag hybrid materials can inhibit strongly the growth of E. coli, S. aureus as well as two antibiotic resistance bacterial strains, P. stutzeri B27, and antibiotic resistance E. coli. Especially, the antibacterial activity quantification and durability of the HT-Ag hybrid materials were also tested. Overall, the HT-Ag hybrid materials are very promising for application in material science and biomedicine fields.

Development of Light-Scribing Process Using L-Ascorbic Acid for Graphene Micro-Supercapacitor

The rapid development of smart technologies is accelerating the growing demand for microscale energy storage devices. This work reports a facile and practical approach to fabricating interdigitated graphene micro-patterns through the LSC process accompanied by the l-ascorbic acid (L-AA) and preheating treatment. Our work offered a higher degree of GO reduction than the conventional microfabrication. It significantly shortened the overall processing time to obtain the micro-patterns with improved electrical and electrochemical performances. The interdigitated MSC composed of 16 electrodes exhibited a high capacitance of 14.1 F/cm3, energy density of 1.78 mWh/cm3, and power density of 69.9 mW/cm3. Furthermore, the fabricated MSC device demonstrated excellent cycling stability of 88.2% after 10,000 GCD cycles and a high rate capability of 81.1% at a current density of 1.00 A/cm3. The fabrication process provides an effective means for producing high-performance MSCs for miniaturized electronic devices.

Fe-CP-based Catalytic Oxidation and Dissipative Self-Assembly of a Ferrocenyl Surfactant Applied in DNA Capture and Release

Dissipative self-assembly plays a vital role in fabricating intelligent and transient materials. The selection and design of the molecular structure is critical, and the introduction of valuable stimuli-responsive motifs into building blocks would bring about a novel perspective on the fuel driven nonequilibrium assemblies. For redox-responsive surfactants, novel methods of catalytic oxidation are very important for their activation/deactivation process through designing fuel input/energy dissipation. As an enzyme with a fast catalytic rate, Fe-based coordination polymers (Fe-CPs) are found to be highly effective oxidase-like enzymes to induce a reversible switch of a ferrocene-based surfactant over a wide range of temperatures and pH. This builds a bridge between the CPs materials and surfactants. Furthermore, glucose oxidase can also induce a switchable transition of a ferrocene-based surfactant. The GOX-catalyzed, glucose-fueled transient surfactant assemblies have been fabricated for many cycles, which has a successful application in a time-controlled and autonomous DNA capture and release process. The intelligent use of enzymes including CPs and GOX in ferrocene-based surfactants will pave the way for the oxidation of redox surfactants, which extends the application of stable or transient ferrocenyl self-assemblies.

Synthesis and characterization of magnetic Ag-Fe3O4@polymer hybrid nanocomposite systems with promising antibacterial application

INTRODUCTION

Bacterial infections caused by different strains of bacteria still one of the most important disorders affecting humans worldwide. Polymers nanocomposite systems could be considered as an alternative to conventional antibiotics to eradicate bacterial infections.

SIGNIFICANCE

In an attempt to enhance the antibacterial performance of silver and iron oxide nanoparticles, decrease their aggregation and toxicity, a polymeric hybrid nanocomposite system combining both nanoparticles is produced.

METHODS

Magnetic Ag-Fe3O4@polymer hybrid nanocomposites prepared using different polymers, namely polyethylene glycol 4000, ethyl cellulose, and chitosan were synthesized via wet impregnation and ball-milling techniques. The produced nanocomposites were tested for their physical properties and antibacterial activities.

RESULTS

XRD, FT-IR, VSM, and TEM results confirmed the successful preparation of hybrid nanocomposites. Hybrid nanocomposites have average crystallite sizes in the following order Ag-Fe3O4@CS (8.9 nm) < Ag-Fe3O4@EC (9.0 nm) < Ag-Fe3O4@PEG4000 (9.4 nm) and active surface area of this trend Ag-Fe3O4@CS (130.4 m2g-1) > Ag-Fe3O4@EC (128.9 m2g-1) > Ag-Fe3O4@PEG4000 (123.4 m2g-1). In addition, they have a saturation magnetization in this order: Ag-Fe3O4@PEG4000 (44.82 emu/g) > Ag-Fe3O4@EC (40.14 emu/g) > Ag-Fe3O4@CS (22.90 emu/g). Hybrid nanocomposites have a pronounced antibacterial action against Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus intermedius compared to iron oxide nanoparticles and positive antibacterial drug. In addition, both Ag-Fe3O4@EC and Ag-Fe3O4@CS have a lower MIC values compared to Ag-Fe3O4@PEG and positive control.

CONCLUSION

Magnetic Ag-Fe3O4 hybrid nanocomposites could be promising antibacterial nanomaterials and could pave the way for the development of new materials with even more unique properties and applications.

Special Issue: Advanced Nanocomposite Materials Based on Graphene Oxide/Reduced Graphene Oxide: Potential Applications and Perspectives

In recent years, graphene oxide (GO) and reduced graphene oxide (r-GO) have received much attention as precursors of graphene-like 2D nanomaterials [...].

Recent Advances in Graphene-Based Nanocomposites for Ammonia Detection

The increasing demand to mitigate the alarming effects of the emission of ammonia (NH3) on human health and the environment has highlighted the growing attention to the design of reliable and effective sensing technologies using novel materials and unique nanocomposites with tunable functionalities. Among the state-of-the-art ammonia detection materials, graphene-based polymeric nanocomposites have gained significant attention. Despite the ever-increasing number of publications on graphene-based polymeric nanocomposites for ammonia detection, various understandings and information regarding the process, mechanisms, and new material components have not been fully explored. Therefore, this review summarises the recent progress of graphene-based polymeric nanocomposites for ammonia detection. A comprehensive discussion is provided on the various gas sensor designs, including chemiresistive, Quartz Crystal Microbalance (QCM), and Field-Effect Transistor (FET), as well as gas sensors utilising the graphene-based polymer nanocomposites, in addition to highlighting the pros and cons of graphene to enhance the performance of gas sensors. Moreover, the various techniques used to fabricate graphene-based nanocomposites and the numerous polymer electrolytes (e.g., conductive polymeric electrolytes), the ion transport models, and the fabrication and detection mechanisms of ammonia are critically addressed. Finally, a brief outlook on the significant progress, future opportunities, and challenges of graphene-based polymer nanocomposites for the application of ammonia detection are presented.