Biological studies and electrical conductivity of paper sheet based on PANI/PS/Ag-NPs nanocomposite

Development of silver-doped copper oxide and chitosan nanocomposites for enhanced antimicrobial activities

Antimicrobial resistance (AMR) has emerged as a significant and pressing public health concern, posing serious challenges to effectively preventing and treating persistent diseases. Despite various efforts made in recent years to address this problem, the global trends of AMR continue to escalate without any indication of decline. As AMR is well-known for antibiotics, developing new materials such as metal containing compounds with different mechanisms of action is crucial to effectively address this challenge. Copper, silver, and chitosan in various forms have demonstrated significant biological activities and hold promise for applications in medicine and biotechnology. Exploring the biological properties of these nanoparticles is essential for innovative therapeutic approaches in treating bacterial and fungal infections, cancer, and other diseases. To this end, the present study aimed to synthesize silver@copper oxide (Ag@CuO) nanoparticles and its chitosan nanocomposite (Chi-Ag@CuO) to investigate their antimicrobial efficacy. Various established spectroscopic and microscopic methods were employed for characterization purposes, encompassing scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Subsequently, the antimicrobial activity of the nanoparticles was assessed through MIC (minimum inhibitory concentration), MBC (minimum bactericidal concentration), and well-disk diffusion assays against Pseudomonas aeruginosa, Acinetobacter baumannii Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans. The size of the CuO-NPs, Ag@CuO, and Chi-Ag@CuO NPs was found to be 70-120 nm with a spherical shape and an almost uniform distribution. The nanocomposites were found to possess a minimum inhibitory concentration (MIC) of 5 μg/mL and a minimum bactericidal concentration (MBC) of 250 μg/mL. Moreover, these nanocomposites generated varying clear inhibition zones, with diameters ranging from a minimum of 9 ± 0.5 mm to a maximum of 25 ± 0.5 mm. Consequently, it is evident that the amalgamation of copper-silver-chitosan nanoparticles has exhibited noteworthy antimicrobial properties in the controlled laboratory environment, surpassing the performance of other types of nanoparticles.

Preparation and performance of bionanocomposites based on grafted chitosan, GO and TiO2-NPs for removal of lead ions and basic-red 46

Wastewater rich in heavy metals and organic compounds represents one of the essential environmental pollutants. Therefore, a practical approach is to fabricate eco-friendly polymer-based systems with a high ability to absorb pollutants. Herein, bionanocomposites consisting of chitosan (Cs) grafted by various monomers, such as acrylamide (Am), acrylic acid (AA), and 4-styrene sulfonic acid (SSA), and hybrid nanoparticles of graphene oxide/titanium dioxide nanoparticles (GO@TiO₂-NPs) were fabricated. The prepared nanomaterials and bionanocomposites characterized via various tools. The data illustrated that the prepared GO had a thickness of 10 nm and TiO₂-NPs had a diameter of 25 nm. In addition, the grafted chitosan (gCs) using Am and SSA had the largest surface area (gCs2; 22.89 nm) and its bionanocomposite (NC5; 104.79 nm). In addition, the sorption ability of the 0.15 g of prepared bionanocomposites to the (100 mg/L) of lead ions (Pb²⁺) and (25 mg/L) of basic-red 46 (BR46) under various conditions has been studied. The results showed that gCs3 and NC5 had the highest adsorption of Pb²⁺ (79.54 %) and BR46 (79.98 %), respectively. The kinetic study results of the sorbents obeyed the Pseudo second-order model. In contrast, the isothermal study followed the Freundlich adsorption model for Pb²⁺ and the Langmuir adsorption model for BR46.

A Novel Trace-Level Ammonia Gas Sensing Based on Flexible PAni-CoFe2O4 Nanocomposite Film at Room Temperature

In this study, we developed a new chemi-resistive, flexible and selective ammonia (NH3) gas sensor. The sensor was prepared by depositing thin film of polyaniline-cobalt ferrite (PAni-CoFe2O4) nanocomposite on flexible polyethylene terephthalate (PET) through an in situ chemical oxidative polymerization method. The prepared PAni-CoFe2O4 nanocomposite and flexible PET-PAni-CoFe2O4 sensor were evaluated for their thermal stability, surface morphology and materials composition. The response to NH3 gas of the developed sensor was examined thoroughly in the range of 1-50 ppm at room temperature. The sensor with 50 wt% CoFe2O4 NPs content showed an optimum selectivity to NH3 molecules, with a 118.3% response towards 50 ppm in 24.3 s response time. Furthermore, the sensor showed good reproducibility, ultra-low detection limit (25 ppb) and excellent flexibility. In addition, the relative humidity effect on the sensor performance was investigated. Consequently, the flexible PET-PAni-CoFe2O4 sensor is a promising candidate for trace-level on-site sensing of NH3 in wearable electronic or portable devices.

Recent Progress in High-Strength and Robust Regenerated Cellulose Materials

High-strength petroleum-based materials like plastics have been widely used in various fields, but their nonbiodegradability has caused serious pollution problems. Cellulose, as the most abundant sustainable polymer, has a great chance to act as the ideal substitute for plastics due to its low cost, wide availability, biodegradability, etc. Herein, the recent achievements for developing cellulose "green" solvents and regenerated cellulose materials with high strength via the "bottom-up" route are presented. Cellulose can be regenerated to produce films/membranes, hydrogels/aerogels, filaments/fibers, microspheres/beads, bioplastics, etc., which show potential applications in textiles, biomedicine, energy storage, packaging, etc. Importantly, these cellulose-based materials can be biodegraded in soil and oceans, reducing environmental pollution. The cellulose solvents, dissolving mechanism, and strategies for constructing the regenerated cellulose functional materials with high strength and performances, together with the current achievements and urgent challenges are summarized, and some perspectives are also proposed. The near future will be an exciting era for high-strength biodegradable and renewable materials. The hope is that many environmentally friendly materials with good properties and low cost will be produced for commercial use, which will be beneficial for sustainable development in the world.

Conducting chitosan/hydroxylethyl cellulose/polyaniline bionanocomposites hydrogel based on graphene oxide doped with Ag-NPs

The current work focuses on a cheap and simple preparation of highly conducting chitosan/hydroxyl ethylcellulose/polyaniline loaded with graphene oxide doped by silver nanoparticles (CS/HEC/PAni/GO@Ag) bionanocomposite as a biodegradable and biocompatible hydrogel for energy storage technology. Scanning electron microscopy (SEM) displays the compatibility of chitosan, hydroxyl ethyl cellulose, and polyaniline and a good distribution of GO@Ag-NPs in bionanocomposite hydrogels. X-ray diffraction (XRD) displayed the structure and existence of GO@Ag-NPs in the matrix. The swelling percentage and the antibacterial activities slightly increased with raising the content of GO@Ag-NPs. Also, the presence of both chitosan and cellulose improves the biodegradation of the fabricated bionanocomposites, which is increased by adding GO. Moreover, the incorporation of 5% GO@Ag-NPs in hydrogels enhances dc-conductivity by about 25 times from 3.37 × 10^-3 to 8.53 × 10^-2 S/cm. The fabricated hydrogels are inexpensive, eco-friendly, and have high capacitance and permittivity, and so they can store electrical energy.

Preparation, film fabrication and gas-sensitive responsive properties of MWCNTs@PS-b-HTPB5-b-PS conductive polymer nanocomposites

Novel nanocomposites consisting of polystyrene-block-polybutadienyl polyhexamethylene dicarbamate-block-polystyrene (PS-b-HTPB5-b-PS) and multiwalled carbon nanotubes (MWCNTs) were designed and prepared via noncovalent interactions. Scanning electron microscopy and transmission electron microscopy observations showed that segregated networks of MWCNTs were formed due to the cladding of PS-b-HTPB5-b-PS, presenting a parallel-arranged topology of the MWCNTs in a continuous PS-b-HTPB5-b-PS phase, which improved the dispersibility of the MWCNTs. The nanocomposites were fabricated into vapor sensing elements to detect CH2Cl2 vapor in the environment, exhibiting excellent responsive sensitivity, reproducibility and a low limit of detection (LOD) of 1 ppm when exposed to CH2Cl2 vapor. The chain extension of HTPB overcame the fragility and improved the tenacity of the thin films, and the responsivity was optimized by adjusting the content of the MWCNTs and the length of the PS chains. The newly developed conductive composites can be applied as a promising vapor sensor to accurately monitor CH2Cl2 vapor in the environment.

A novel electromagnetic biodegradable nanocomposite based on cellulose, polyaniline, and cobalt ferrite nanoparticles

Biodegradable, antimicrobial, and semiconducting cellulosic composite was synthesized by in-situ polymerization of polyaniline in the presence of cellulose. The cobalt ferrite nanoparticles (CFO-NPs) were added during the polymerization process to acquire this composite magnetic property. The CFO-NPs were prepared by sol-gel method with average particles size less than 50 nm. The nanocomposites were characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). In addition, their magnetic, dielectric constant, dielectric loss, and conductivity behaviors were studied. The magnetization (M_s) and conductivity increased up to 3.7 emu/g and 3.5 × 10^-3 S/cm, respectively, with increasing CFO-NPs content. The prepared electromagnetic nanocomposite exhibits highly efficient biodegradability and antimicrobial activity against Escherichia coli, Bacillus subtilis, and Candida albicans. The antimicrobial activity increased with increasing CFO-NPs while the biodegradability decreased.

Preparation of Chitosan-grafted-Polyvinyl acetate Metal Nanocomposite for producing Multifunctional Textile Cotton Fabrics

Chitosan-g-polyvinyl acetate (Cs-g-PVAc) was synthesized successfully using redox copolymerization using potassium persulfate as initiator. TiO₂ and TiO₂ doped ZnO which previously prepared by sol-gel technique added for preparing emulsion from polymer - metal oxide nanocomposites. Cotton fabrics were treated with prepared emulsions using citric acid and sodium hypophosphite. XRD measurements prove that the prepared TiO₂ nanoparticles corresponded to anatase phase with average crystallite size d = 15.98 nm where the crystallinity and crystallite size decreased for Zn doped TiO₂ where d = 11.7 nm. FTIR indicates that the exhibition of grafting process and formation polymer metal oxide nanocomposite. Samples treated with Copolymer showed the highest antibacterial properties. However, the copolymer doped with TiO₂ and TiO₂/ZnO showed lowest contact angle and affects positively on its photocatalytic performance. SEM and TEM micrographs confirmed that the prepared metal oxides are in nano scales, where TiO₂ is smaller than TiO₂/ZnO which effects on the band gap of TiO₂/ZnO to be larger than TiO₂ and consequently decreased on the photocatalytic properties TiO₂/ZnO of samples compared to TiO₂ sample under the halogen lamp.

A printable voltammetric genosensor for tumour suppressor gene screening based on a nanocomposite of Ceria NPs–GO/nano-PANI

A specific sequence of the adenomatous polyposis coli (APC) gene is detected electrochemically using a new nanomaterial based bio-sensing platform.

New Supercapacitors Based on the Synergetic Redox Effect between Electrode and Electrolyte

Redox electrolytes can provide significant enhancement of capacitance for supercapacitors. However, more important promotion comes from the synergetic effect and matching between the electrode and electrolyte. Herein, we report a novel electrochemical system consisted of a polyanilline/carbon nanotube composite redox electrode and a hydroquinone (HQ) redox electrolyte, which exhibits a specific capacitance of 7926 F/g in a three-electrode system when the concentration of HQ in H₂SO₄ aqueous electrolyte is 2 mol/L, and the maximum energy density of 114 Wh/kg in two-electrode symmetric configuration. Moreover, the specific capacitance retention of 96% after 1000 galvanostatic charge/discharge cycles proves an excellent cyclic stability. These ultrahigh performances of the supercapacitor are attributed to the synergistic effect both in redox polyanilline-based electrolyte and the redox hydroquinone electrode.