Green Chemical Reduction Research Articles

Thermosensitive curcumin/silver/montmorillonite-F127 hydrogels with synergistic photodynamic/photothermal/silver ions antibacterial activity.

Bacterial infections and the emergence of super-resistant bacteria pose a significant risk to human health. Effective sterilization to prevent the development of bacterialdrug resistance remains a challenge. Herein, curcumin/silver/montmorillonite (Cur/Ag/Mt) was prepared through a green chemical reduction method with montmorillonite as the carrier, curcumin as the reducing agent and the capping agent, and citric acid as the structure guide agent. Then, a novel dual light-responsive and thermosensitive Pluronic F127-based hydrogel (CAM-F) was prepared by encapsulating Cur/Ag/Mt within the F127 hydrogel. The Cur/Ag/Mt showed strong absorption in the near-infrared region that efficiently converts light into heat for photothermal therapy when the molar ratio of curcumin to silver nitrate was 2 : 1. Specifically, triangular silver nanoparticles reduced by curcumin were immobilized on the Mt layers, which could enhance photodynamic therapy by the metal-enhanced singlet oxygen and metal-enhanced fluorescence mechanisms. Upon combining 405 nm and 808 nm laser irradiation, the CAM-F hydrogel could simultaneously generate reactive oxygen species, increase the local temperature, and sustain the release of Ag+, thus displaying excellent bactericidal performance against Gram-negative and Gram-positive bacteria. The antibacterial rates of CAM-F hydrogels were 99.26 ± 0.95% and 99.95 ± 0.98% for Escherichia coli and Staphylococcus aureus, respectively. The findings suggest the potential of the CAM-F hydrogel as a stable, biologically safe, and broad-spectrum antimicrobial material. The thermosensitive CAM-F hydrogels for synergetic phototherapy may provide a promising strategy for solving clinical problems caused by pathogenic infections.

Green synthesis of platinum nanoparticles as a robust electrocatalyst for methanol oxidation reaction: Metabolite profiling and antioxidant evaluation

A novel, low-cost, and environmentally friendly method of synthesising biogenic platinum nanoparticles (Pt NPs) was employed using biomass sugar cane (Saccharum officinarum L.) bagasse extract (SBE) as the reducing agent. Pt NPs derived from this biosynthesis route were thoroughly characterised by High-resolution transmission electron microscopy (HRTEM), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis. Due to the involvement of bio-reductive metabolites during biosynthesis, their metabolite profiles were identified using gas chromatography-mass spectrometry (GC-MS) and in-vitro antioxidant activities. Eleven major metabolite compounds from the SBE classified as phenol, pyrazole, furan, pyran, epoxide, long-chain fatty acid, sterol glycoside, and mixed oxygenated compounds may be responsible for the bio-reduction process. The biogenic Pt NPs endowed a high antioxidant property that can scavenge DPPH free radicals by 81.9%, with an inhibitory effect (IC50) of 37.60 μg/mL and ferric reducing antioxidant power assay (FRAP) of 57.58 μmol FeSO4/g. Furthermore, the biogenic Pt NPs deliver superior electrocatalytic activity in methanol oxidation reactions with tunable Pt ions concentration, PtCl62−, from 0.5 to 1.75 mM, with a maximum electrochemical active surface area (ECSA) of 93.41 m2 g−1 and a mass activity/specific activity of 581.50 mA mg−1/1.25 mA cm−2Pt, which is 3.67 times higher than that of commercial Pt black (158.12 mA mg−1). This study demonstrates that green chemical reduction using plant extracts is a viable method for producing biogenic Pt NPs for energy conversion and health applications, owing to its improved electrocatalytic activity and profound antioxidant properties.

Electrochemical and Electroconductive Behavior of Silk Fibroin Electrospun Membrane Coated with Gold or Silver Nanoparticles.

The surface modification of materials obtained from natural polymers, such as silk fibroin with metal nanoparticles that exhibit intrinsic electrical characteristics, allows the obtaining of biocomposite materials capable of favoring the propagation and conduction of electrical impulses, acting as communicating structures in electrically isolated areas. On that basis, this investigation determined the electrochemical and electroconductive behavior through electrochemical impedance spectroscopy of a silk fibroin electrospun membrane from silk fibrous waste functionalized with gold or silver nanoparticles synthetized by green chemical reduction methodologies. Based on the results obtained, we found that silk fibroin from silk fibrous waste (SFw) favored the formation of gold (AuNPs-SFw) and silver (AgNPs-SFw) nanoparticles, acting as a reducing agent and surfactant, forming a micellar structure around the individual nanoparticle. Moreover, different electrospinning conditions influenced the morphological properties of the fibers, in the presence or absence of beads and the amount of sample collected. Furthermore, treated SFw electrospun membranes, functionalized with AuNPs-SFw or AgNPS-SFw, allowed the conduction of electrical stimuli, acting as stimulators and modulators of electric current.

Moisture effects on mechanical behavior of CNF-RGO nanocomposites showing electrical conductivity

Water-processed nanocomposites based on cellulose nanofibrils (CNF and 2D platelets are sustainable alternatives to nanocomposites from fossil-based polymers. The degree of dispersion of 2D platelets in CNF matrix is critical to mechanical properties, but reduced graphene oxide (RGO) has poor hydrocolloidal stability. This is addressed by forming electrically conductive and strong CNF-RGO nanocomposites by green chemical reduction of wet, vacuum-filtered CNF-GO cakes, taking advantage of the colloidal dispersibility of GO platelets in CNF, as characterized in the solid nanocomposite by SAXS, WAXS and FE-SEM. CNF-RGO nanocomposite with 2 wt% RGO shows a Younǵs modulus of 20.4 GPa and tensile strength of 319 MPa, with considerable ductility at 50 % RH. Although CNF-GO shows much higher moisture sorption than CNF-RGO at 90 %RH, the CNF-GO mechanical properties are higher, for thermodynamic reasons, MD simulations predict dry, hydrogen-bonded CNF-GO interfaces even in wet conditions, and this can explain the better performance of CNF-GO.

Novel epoxy adhesives based on conductive micron‐sized silver flowers

AbstractLow silver contents are desirable for electrically conductive adhesives (ECAs) due to the high cost of silver. In the present work, micro‐sized flower‐like silver particles (MFSPs) with long and thin petals are prepared by a novel, green, and facile chemical reduction method in an aqueous solution. The effects of reactant mass ratio and reactant concentration are investigated to control the morphology and size of MFSPs. Three kinds of MFSPs with different sizes are filled into an epoxy resin to prepare novel ECA. Due to the easily formed conductive paths by such morphological silver particles, the as‐prepared MFSP/epoxy composite adhesive has a low percolation threshold, a high conductivity, and high adhesion strength at a very low silver content. When considering the optimal combination of low electrical resistance and high adhesion strength, the MFSP obtained at the 1.5:1 ratio of ascorbic acid to silver nitrate is promising for preparing the ECA with a low Ag content of 30 wt% which is the lowest content for ECAs compared with the literature. The synthesis process of MFSPs has the advantages of mild condition, simple process, and environmental friendship. This study provides a new way to prepare highly conductive Ag/epoxy adhesives with low silver contents.

Dual nanocatalysts co-decorated three-dimensional, laser-induced graphene hybrid nanomaterials integrated with a smartphone portable electrochemical system for point-of-care non-enzymatic glucose diagnosis

Non-enzymatic biosensors based on various nanomaterials with large surface-volume ratios and high catalytic efficiencies have been proposed to compensate for the non-stability and high cost of enzymatic biosensors. However, the construction of a stable, highly sensitive, flexible, three-dimensional (3D), microstructured, non-enzymatic biosensor integrated with a smartphone-based portable system has been challenging. Herein, highly conductive laser-induced graphene (LIG) array with a honeycomb-like 3D microstructure co-decorated with copper(I) oxide and gold nanocatalysts was developed via simple and green electro-deposition and chemical reduction approaches for a miniaturized electrochemical flexible non-enzymatic biosensor. SEM, XRD, Raman and XPS analyzations indicated that the Cu2O and Au nanocatalysts co-decorated three-dimensional, laser-induced graphene hybrid nanomaterials were developed successfully. The signal of the biosensor was improved by more than 10 fold compared to the LIG alone due to the co-decorated with copper(I) oxide and gold nanocatalysts. The fabricated electrochemical biochip was integrated with a smartphone-based microstation for glucose monitoring, presenting a larger linear interval of 1–20 mM with an excellent sensitivity of 236 μA/mM/cm2 and a relatively low detection limit of 0.31 μM. Noticeably, the biochip could measure blood sugar on curved surfaces and still deliver stable sensing signals after being bent back-and-forth 25 times. The novel biosensor is a potentially valuable flexible electronic device. The hybrid nanomaterials developed in this work may be applicable to other biosensing, catalytic, and energy devices (supercapacitors and batteries).

Synthesis and characterization of a collagen-based composite material containing selenium nanoparticles.

Multidrug-resistant bacterial strains represent an emerging global health threat and a great obstacle for bone tissue engineering. One of the major components of the extracellular matrix of the bone is a collagen protein, while selenium is an element that has antimicrobial potential, and is also important for bone metabolism and bone health. Here we represent the incorporation of selenium nanoparticles (SeNPs) synthesized by the green chemical reduction method into collagen gels to produce a composite material, collagen/SeNPs, with antimicrobial properties. The samples were comprehensively characterized by zeta potential measurements, dynamic light scattering inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), optical microscopy, field-emission scanning electron microscopy (FE-SEM), and differential scanning calorimetry The cytotoxicity of the SeNPS, as well as collagen/SeNPs, was tested on the MRC-5 cells. It was revealed that collagen/SeNPS expressed a lower cytotoxic effect. Collagen/SeNPs showed significant antibacterial activity against all tested Gram-positive strains, the major causative agents of orthopedic infections as well as Candida albicans. Furthermore, three-dimensional β-tricalcium phosphate (3D-TCP) scaffolds were fabricated by a well-established 3D printing (lithography) method, and afterward preliminary coated by newly-synthesized SeNPs or collagen/SeNPs. In addition, uncoated 3D-TCP scaffolds as well as coated by collagen/SeNPs were subjected to biofilm formation. The production of Staphylococcus aureus biofilm on coated scaffolds by collagen/SeNPs was significantly reduced compared to the uncoated ones.

Green Carbon Nanostructures for Functional Composite Materials.

Carbon nanostructures are widely used as fillers to tailor the mechanical, thermal, barrier, and electrical properties of polymeric matrices employed for a wide range of applications. Reduced graphene oxide (rGO), a carbon nanostructure from the graphene derivatives family, has been incorporated in composite materials due to its remarkable electrical conductivity, mechanical strength capacity, and low cost. Graphene oxide (GO) is typically synthesized by the improved Hummers’ method and then chemically reduced to obtain rGO. However, the chemical reduction commonly uses toxic reducing agents, such as hydrazine, being environmentally unfriendly and limiting the final application of composites. Therefore, green chemical reducing agents and synthesis methods of carbon nanostructures should be employed. This paper reviews the state of the art regarding the green chemical reduction of graphene oxide reported in the last 3 years. Moreover, alternative graphitic nanostructures, such as carbons derived from biomass and carbon nanostructures supported on clays, are pointed as eco-friendly and sustainable carbonaceous additives to engineering polymer properties in composites. Finally, the application of these carbon nanostructures in polymer composites is briefly overviewed.

Silver nano-particles' size prediction using deep learning model with green method

When it comes to casting technologies and other production processes such as welding, DL models minimise the need for costly experimental inquiry. One of the most important criteria in nanotechnology is the measurement of particle size. They've received a lot of interest for their chemical, physical, and clinical uses because of their outstanding qualities. By adopting a green chemical reduction process, the nano-silver crystals are generated in the biopolymer interface without any agglomeration. Nano-metal production relies on precise control of particle size, and this approach provides that. For the prediction size of Ag-NPs via the green approach, a hybrid ideal of Long-Short Term Memory (LSTM) and Convolutional Neural Network (CNN) and model is presented in this research. Temperature, starch stabiliser, and AgNO3 concentration are among the experimental variables fed into the CNN-LSTM model. The size of a nano particle is the output of the CNN-LSTM model. Making three subsets of the experimental data for training, validation, and testing was one of the initial steps in creating an adapting model. The silver nanoparticles were identified using X-ray diffraction and transmission electron microscopy. Ag-NPs' crystallographic airplanes were found to be face-centered cubic, according to XRD analysis (fcc).When comparing with other existing classifiers, DNN achieved high performance on precision, i.e. 89.87%, and this is due to the presence of simple structure. The CNN and auto encoder achieved nearly 82% and 80% of accuracy, where LSTM achieved 77.25% of accuracy and proposed CNN-LSTM achieved 83.50% of recall.

GREEN REDUCTION OF SOME AROMATIC NITRO COMPOUNDS BY IMMOBILIZED BAKER’S YEAST

Green chemical reduction of selected aromatic nitro compounds like o-nitrobenzoic acid, m-nitrobenzoic acid and p-nitrobenzoic acid will be done by involving microbial transformation. In microbial transformation Baker’s Yeast (Saccharomyces cerevisiae) is used in immobilized form. Utilisation of baker’s yeast for reduction of nitro compounds is cost effective and environmental friendly .The reduction products will be isolated and purified by chromatographic techniques and characterized on the basis of spectral analysis viz. IR, NMR spectral data. KEYWORDS: Baker’s Yeast, Chromatographic technique, Green reduction, Microbial transformation, Spectroscopic technique.

Analysis by response surface methodology of gold nanoparticles obtained by green chemical reduction using aqueous coffee pulp extract (<i>Coffea arabica</i>)

Green synthesis of gold nanoparticles using an aqueous coffee (<i>Coffea arabica</i>) pulp extract as a reducing agent was achieved and analyzed by response surface methodology, given the diverse applicability of these nanoparticles containing a wide range of phenolic compounds from the coffee pulp extract. Three factors (precursor concentration, reducing agent concentration, and reaction time) were considered and their combined effects on the maximum intensity (<i>MA</i>), particle size (<i>d</i>), and particle density (<i>N</i>) were analyzed. An opposing effect between the precursor and reducing agent was observed during synthesis because while the precursor increased <i>d</i> and diminished <i>N</i>, the reducing agent diminished <i>d</i> and increased <i>N</i>. These effects were observed simultaneously through the response surfaces of <i>d</i> and <i>N</i>. This methodology allowed the synthesis of nanoparticles with an average particle size between 5–22 nm and <i>N</i> around 2.9x10<sup>11</sup>−3.7x10<sup>13</sup> (part/mL), depending on the response surface methodology, Box-Behnken design. The R<sup>2</sup> value determined for all cases was 0.98 (<i>MA</i>), 0.99 (<i>d</i>), and 0.97 (<i>N</i>), clearly indicating that the model can be used to predict or design the response variables in the design space. Finally, Fourier transform infrared measurements showed that the organic compounds present in the aqueous coffee pulp extract were coating the surface of the gold nanoparticles. The proposed methodology could contribute to the design of new alternatives for the synthesis of specific nanostructures with potential applications in the therapeutic area.

Size-Controlled Transformation of Cu2O into Zero Valent Copper within the Matrix of Anion Exchangers via Green Chemical Reduction.

Composite materials containing zero valent copper (ZVC) dispersed in the matrix of two commercially available strongly basic anion exchangers with a macroreticular (Amberlite IRA 900Cl) and gel-like (Amberlite IRA 402OH) structure were obtained. Cu0 particles appeared in the resin phase as the product of the reduction of the precursor, i.e., copper oxide(I) particles previously deposited in the two supporting materials. As a result of a one-step transformation of preformed Cu2O particles as templates conducted using green reductant ascorbic acid and under mild conditions, macroporous and gel-type hybrid products containing ZVC were obtained with a total copper content of 7.7 and 5.3 wt%, respectively. X-ray diffraction and FTIR spectroscopy confirmed the successful transformation of the starting oxide particles into a metallic deposit. A scanning electron microscopy study showed that the morphology of the deposit is mainly influenced by the type of matrix exchanger. In turn, the drying steps were crucial to its porosity and mechanical resistance. Because both the shape and size of copper particles and the internal structure of the supporting solid materials can have a decisive impact on the potential applications of the obtained materials, the results presented here reveal a great possibility for the design and synthesis of functional nanocrystalline solids.

Green Solid-State Chemical Reduction of Graphene Oxide Supported on a Paper Substrate

The reduction of graphene oxide (GO) thin films deposited on substrates is crucial to achieve a technologically useful supported graphene material. However, the well-known thermal reduction process cannot be used with thermally unstable substrates (e.g., plastics and paper), in addition photo-reduction methods are expensive and only capable of reducing the external surface. Therefore, solid-state chemical reduction techniques could become a convenient approach for the full thickness reduction of the GO layers supported on thermally unstable substrates. Here, a novel experimental procedure for quantitative reduction of GO films on paper by a green and low-cost chemical reductant (L-ascorbic acid, L-aa) is proposed. The possibility to have an effective mass transport of the reductant inside the swelled GO solid (gel-phase) deposit was ensured by spraying a reductant solution on the GO film and allowing it to reflux in a closed microenvironment at 50 °C. The GO conversion degree to reduced graphene oxide (r-GO) was evaluated by Fourier transform infrared spectroscopy (FT-IR) in attenuated total reflectance (ATR) mode and X-ray Diffraction (XRD). In addition, morphology and wettability of GO deposits, before and after reduction, were confirmed by digital USB microscopy, scanning electron microscopy (SEM), and contact angle measurements. According to these structural characterizations, the proposed method allows a bulky reduction of the coating but leaves to a GO layer at the interface, that is essential for a good coating-substrate adhesion and this special characteristic is useful for industrial exploitation of the material.

Fast and cost-effective room temperature synthesis of high quality graphene oxide with excellent structural intactness

Graphene oxide (GO) is well known as a key material to the commercialization of graphene-based applications due to its excellent processability and abundant starting materials. However, producing high quality GO with excellent structural intactness still remains a challenge despite the significant research effort over the past decade. Herein, we demonstrate an effective approach to achieving well-oxidized GO within only 5 h of oxidation time at 5 °C or 25 °C from expanded graphite as a starting material. Our finding reveals that the well-oxidized GO synthesized at 25 °C can regain more graphitic sp2 networks and thus becomes as conductive as the GO prepared at 5 °C by means of thermal annealing or green chemical reduction. We also found that green chemical reduction using vitamin C (VC) is more efficient in restoring the electrical conductivity and reducing the defects in the GO produced at room temperature. The protocol reported in this paper offers a promising, sustainable way to fabricate high quality GO with minimal energy input, while being cost-effective.

Synthesis of zinc oxide nanostructures using orange peel oil for fabricating chitosan-zinc oxide composite films and their antibacterial activity

There is growing need for environmentally friendly plastics to tackle problems of waste disposal. This makes it important to explore options to make biodegradable materials for packaging and coating applications. In this study we have leveraged the inherent anti-bacterial, biodegradable properties of chitosan (CS) and anti-bacterial and UV-absorbing properties of Zinc Oxide (ZnO) to develop CS-ZnO composite films. ZnO nanostructures (ZnO NS) were synthesized using orange peel oil (OP) by green chemical reduction method. ZnO incorporated films of chitosan were evaluated for their physicochemical properties. Presence of ZnO NS was confirmed using its characteristic signatures in UV-Visible spectrum, fluorescence measurement and FT-IR spectrum. The ZnO NS gave absorption and fluorescence maxima at 379 nm and 465 nm respectively. FT-IR spectra confirmed the vibration of the Zn-O at ~470 cm−1. The composite films prevented moisture permeability as compared to plain chitosan films. Chitosan-ZnO composite films showed higher tensile strength than plain chitosan films and also selectively blocked radiations in UV region due to UV-absorbing property of ZnO. The composite films also demonstrated good adhesion on glass and polystyrene substrates, enhanced tensile strength and anti-bacterial activity against E.Coli, compared to CS films, suggesting the potential of the developed films as a biodegradable, coating and packaging material.

InVivo Disintegration and Bioresorption of a Nacre-Inspired Graphene-Silk Film Caused by the Foreign-Body Reaction.

SummaryGraphene-based substrates are emerging as a promising functional platform for biomedical applications. Although dispersible graphene sheets have been demonstrated to be biodegradable, their assembled macroscopic architectures are biopersistent because of strong π-π interactions. In this study, we developed a nacre-inspired graphene-silk nanocomposite film by vacuum filtration with a subsequent green chemical reduction procedure. The “brick-and-mortar” architecture not only ensures the mechanical and electrical properties of the film but also endows it with disintegrable and bioresorbable properties following rat subcutaneous implantation. Furthermore, covalent cross-linking leads to the formation of graphene with decreased interlayer spacing, which effectively prolongs the residence time in vivo. We found that enzymatic treatment created microcracks on the film surface and that the foreign-body reaction was involved in the deformation, delamination, disintegration, and phagocytosis processes of the nanocomposite films. This bioinspired strategy paves the way for the development of high-performance graphene-based macroscopic biomaterials with tunable bioresorbability.

Simple synthesis of the Au-GQDs@AgPt Yolk-shell nanostructures electrocatalyst for enhancing the methanol oxidation

Au-GQDs@AgPt Yolk-shell nanostructures with Au-GQDs yolk and AgPt alloy shell have been synthesized through a green wet chemical reduction method. In this process employed Au-GQDs as a yolk to obtain Au-GQDs@Ag nanoparticles (NPs), and then galvanic replacement reaction occurred between PtCl 6 2- and Ag to fabricate Au-GQDs@AgPt Yolk-shell nanostructures. GQDs served as a structure-directing and dispersing agent to prepare homogeneous shell. The electrocatalytic performance of the as-synthesized Au-GQDs@AgPt Yolk-shell nanostructures for methanol oxidation reaction (MOR) is studied by cyclic voltammetry (CV) and chronoamperometry (CA). The catalyst has displayed excellent specific activity (33.20 mA cm −2 ), which is approximately 7 times higher than those of commercial Pt/C. And its CO tolerance and stability for MOR are also greatly improved. The results attribute to their particular structure (Yolk-shell nanostructures), electron effect with Ag and Pt, electron transport between GQDs and AgPt shell. The present strategy can provide an environment-friendly and valuable way to fabricate multicomponent nanostructures with Yolk-shell nanostructures. Schematic illustration demonstrates the structural and compositional features of the porosity Au-GQDs@AgPt Yolk-shell nanostructures as an efficient MOR catalyst. • The unique Au-GQDs@AgPt Yolk-shell nanostructures were synthesized through a green wet chemical reducation method. • GQDs serve as a structure-directing and dispersing agent to prepare homogenous shell. • Au-GQDs@AgPt Yolk-shell enhanced catalytic performance, CO tolerance and stability for methanol oxidation reaction. • The Yolk-shell nanostructures, electron effect and electron transport are imporatant for improving catalytic performance.

Preparation and characterization of antifungal colloidal copper nanoparticles and their antifungal activity against Fusarium oxysporum and Phytophthora capsici

Copper nanoparticles (CuNPs) possess a promising antibacterial and antifungal activity with low-cost reagent and fabrication. In this study, we report the antifungal activity of pure CuNPs against Fusarium oxysporum (F. oxysporum) and Phytophthora capsici (P. capsici). CuNPs were prepared by reducing Cu2+ from copper(II) chloride dihydrate via a green chemical reduction agent using ascorbic acid as both reducing agent and antioxidant agent in aqueous media and polyvinylpyrrolidone as a stabilizer. The effect of the solution pH, reduction time, ascorbic-acid-to-Cu2+ molar ratio, role of stabilizing agent polyvinylpyrrolidone to particle size of CuNPs were studied. The antifungal activity of CuNPs at different concentrations and different particle sizes against two plant pathogenic fungi F. oxysporum and P. capsici has been tested by the agar disc diffusion technique. Characterizations were carried out by X-ray diffraction measurements, transmission electron microscopy, and ultraviolet–visible light, which revealed that the CuNPs obtained at different synthesis conditions have different particles size, resulting in different antifungal activities. The synthesized CuNPs demonstrated significant antifungal activity against F. oxysporum and P. capsici. F. oxysporum and P. capsici were entirely inhibited at the concentration of CuNPs of 30 ppm after 3 days of incubation and 7.5 ppm after 1 day of incubation, respectively. Our results suggest that synthesized CuNPs can be used as a novel antifungal agent in agriculture to control the plant pathogenic fungi of F. oxysporum and P. capsici.

Functionalization of polypropylene nonwoven fabrics using cold plasma (O2) for developing graphene-based wearable sensors

Melt blown-Nonwoven Polypropylene based materials have numerous applications, such as nonwoven fabrics, filtration membranes used in clothing and potential industrial use due to its higher breathability, durability, absorbency, and filtration properties. Nonwoven PP-fabrics are very often used to develop wearable articles such as garments. In this research melt blown-nonwoven polypropylene (NW-PP) membranes were functionalized using (O2) cold plasma for the conversion of highly hydrophobic into hydrophilic nature to enhance the absorption and adhesion of graphene films on the fiber surface. The graphene oxide (GO) and NW membrane was successfully introduced on the fibrous mat and reduced into reduced Graphene oxide (rGO) with green chemical and thermal reduction. L-Ascorbic Acid was used as a reducing agent at a low-temperature microwave-assisted reduction at 90 °C. The as developed NW membrane was connected two copper electrodes and used as wearable pressure (WP) sensors. The physical sensor responds with different stretching and bending cycles under dynamic pressure of loading and unloading. The sensitivity of the developed pressure sensor was 0.050 kPa−1 in a wide pressure range (0–60 kPa). The resultant rGO coated NW-PP wearable pressure sensor (RNPWP) is capable of responding to human body movement and motion. The study demonstrates that mass production on an industrial scale graphene-based conductive nonwoven PP fabric potentially replaces the metal-based conductive wearable textiles for physical sensors.

Graphene and graphene oxide-coated polyamide monofilament yarns for fiber-shaped flexible electrodes

In this study, polyamide monofilament yarn of 3000 tex was coated with graphene oxide (GO) nanomaterial using dip-coating method. The graphene oxide layer was then reduced with green chemical reduction method, resulting in a reduced graphene oxide-coated monofilament yarn. The properties of the graphene oxide and reduced graphene oxide-coated polyamide monofilament yarns were characterized by performing physical, electrical, optical, and morphological investigations. The lowest sheet resistance was measured from seven-layer graphene-coated polyamide monofilament yarn as 3.09 kΩ/sq. Moreover, it was measured that 90° and 180° bent seven-layer graphene-coated polyamide monofilament yarns had 3.57 and 3.81 kΩ/sq sheet resistance, respectively. Additionally, while PA monofilament yarn has 73.5% transmittance at 550 nm; seven-layer GO and seven-layer graphene have 18.8 and 4.5%, respectively, as expected. On the other hand, the contact angle increased with the reduction of graphene oxide layer on monofilament yarn. The fabricated graphene-coated polyamide monofilament yarns can be used in electrotextiles, solar cells, sensors, and OLEDs as fiber-shaped flexible electrodes.