Surface Functionalization of “Rajshahi Silk” Using Green Silver Nanoparticles

Fabricating Antibacterial Polyethylene Terephthalate Substrates Through an Industrial Approach by Applying Emulsions of Copper-Based Nanoparticles

In this research, various emulsions of copper-based nanoparticles were synthesized through the chemical reduction method followed by utilizing the pad–dry–cure technique as an industrial approach to manufacturing bactericidal polyethylene terephthalate (PET) substrates. Copper sulfate/copper acetate, sodium hypophosphite (SHP)/ascorbic acid, and cetyltrimethylammonium bromide were employed as salts, reducing agents, and stabilizers, respectively. Also, a spin finish oil was used for forming an emulsion. The effects of type and amount of copper salt and reductant as well as the use of resin and stabilizer were investigated concerning antibacterial activities, weight, and color changes of coated samples to find optimum formulation. Field-emission scanning electron microscope (FESEM) images, mapping/energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD) pattern, Raman spectroscopy, and UV–visible spectrophotometer was proved successful in synthesis and loading of copper-based emulsions on the PET substrates. The results revealed that change of copper salt, substituting SHP with ascorbic acid, the addition of resin, and the use of surfactant yielded negligible effect, enhancing impact, reducing the influence, and improving efficacy on bactericidal characteristics of the treated samples, respectively. Based on findings, the samples coated by emulsion containing only copper sulfate/SHP and emulsion including only copper acetate were considered optimum samples indicating 100% bactericidal properties against both S. aureus and E. coli pathogenic bacteria. Despite showing bactericidal activities, it was further found that the treated samples exhibited cell toxicity toward human skin cells implying their applications in indirect contact usages. Coated samples further indicated a good washing fastness even after 20 washing cycles. This route can be considered as a facile industrially applicable method for imparting bactericidal properties to polymeric substrates. Furthermore, such emulsions can potentially be consumed as an antibacterial spin finish oil in melt-spinning to develop antibacterial textiles.

Polysaccharides and Metal Nanoparticles for Functional Textiles: A Review

Nanotechnology is a powerful tool for engineering functional materials that has the potential to transform textiles into high-performance, value-added products. In recent years, there has been considerable interest in the development of functional textiles using metal nanoparticles (MNPs). The incorporation of MNPs in textiles allows for the obtention of multifunctional properties, such as ultraviolet (UV) protection, self-cleaning, and electrical conductivity, as well as antimicrobial, antistatic, antiwrinkle, and flame retardant properties, without compromising the inherent characteristics of the textile. Environmental sustainability is also one of the main motivations in development and innovation in the textile industry. Thus, the synthesis of MNPs using ecofriendly sources, such as polysaccharides, is of high importance. The main functions of polysaccharides in these processes are the reduction and stabilization of MNPs, as well as the adhesion of MNPs onto fabrics. This review covers the major research attempts to obtain textiles with different functional properties using polysaccharides and MNPs. The main polysaccharides reported include chitosan, alginate, starch, cyclodextrins, and cellulose, with silver, zinc, copper, and titanium being the most explored MNPs. The potential applications of these functionalized textiles are also reported, and they include healthcare (wound dressing, drug release), protection (antimicrobial activity, UV protection, flame retardant), and environmental remediation (catalysts).

Combination of wet fixation and drying treatments to improve dye fixation onto spray-dyed cotton fabric

The conventional dyeing process requires a substantial amount of auxiliaries and water, which leaches hazardous colored effluents to the environment. Herein, a newly developed sustainable spray dyeing system has been proposed for cotton fabric in the presence of reactive dyes, which has the potential to minimize the textile dyeing industries environmental impact in terms of water consumption and save significant energy. The results suggest that fresh dye solution can be mixed with an alkali solution before spray dyeing to avoid the reactive dye hydrolysis phenomenon. After that, drying at 60-100 °C, wet fixation treating for 1-6 min, and combined treatments (wet fixation + drying) were sequentially investigated and then dye fixation percentages were around 63-65%, 52-70%, and above 80%, respectively. Following this, fixation conditions were optimized using L₁₆ orthogonal designs, including wet fixation time, temperature, dye concentration, and pH with four levels where the "larger-the-better" function was selected to maximize the dye fixation rate. Additionally, the color uniformity and wash and rubbing fastnesses were at an acceptable level when both treatments were applied. Finally, the dyes were hydrolyzed after wet fixation, and the hydrolysis percentages were enhanced after the drying process.

Ultrasonically developed silver/iota-carrageenan/cotton bionanocomposite as an efficient material for biomedical applications

In this approach, we assembled AgNps on cotton by using iota-carrageenan as a carbohydrate polymer under ultrasonic waves. UV-Vis spectroscopy revealed that iota-carrageenan free radicals increased the absorbance values of AgNps at 438 nm under ultrasonic vibration. We also observed an effective reduction of AgNps by color hue changes in the colloidal dispersions, ranging from pale to dark yellow. Interestingly, the zeta potential values for the AgNps changed from -8.5 to -45.7 mV after incorporation with iota-carrageenan. Moreover, iota-carrageenan reduced the average particle sizes of AgNps/iota-carrageenan nanocomposite particles. Fourier transform infrared (FTIR) spectra proved the successful fabrication of AgNps/iota-carrageenan/cotton nanocomposites by shifting two bands at 3257 and 990 cm^-1. Quantum Chemistry and Molecular Dynamics demonstrated strong interactions between AgNps and iota-carrageenan by changes in the bond lengths for CC, CH, CO, SO. Furthermore, new energy levels were generated in iota-carrageenan's molecules by exciting electrons under ultrasonic vibration. According to the thermal gravimetric analysis (TGA) results, fabrication of AgNps/iota-carrageenan on cotton reduced the thermal stability of the resultant AgNps/iota-carrageenan/cotton nanocomposites. The average friction coefficient values of nanocomposite samples were increased in weft-to-warp direction that can be an advantage for wound healing, antimicrobial treatment and drug delivery applications. We did not observe reduction in the mechanical properties of our AgNps incorporated nanocomposites. Furthermore, the samples were tested for possible cytotoxicity against primary human skin fibroblast cells and no toxicity was observed.

Bioreduction (AuIII to Au0) and stabilization of gold nanocatalyst using Kappa carrageenan for degradation of azo dyes

Colloidal gold nanoparticles (AuNPs) have been used in high technology applications due to their optical and electronic properties. Unfortunately, these broader applications are severely hampered by their agglomeration tendency and instability. Therefore, in this study, highly stable and aggregation resistant AuNPs were synthesized using Kappa carrageenan (κ-car) media (as a reducing and stabilizing agent) by a green synthesis protocol. The effect of different factors of reaction such as the concentration of κ-car (C_κ-car %), reaction time (t), temperature (T), and solution pH (here after simply define to 'reaction parameters') was studied by one-variable-at-a-time technique to optimize the yield production of AuNPs. The characterization of AuNPs synthesized at optimum conditions revealed that the particles are spherical in shapes, smaller in size (13.5 ± 5.1 nm) with a narrow distribution, highly crystalline (d-spacing = 0.230 nm) in nature, well stabilized (zeta potential = -22.1 mV) by coating by a thin layer of κ-car carbohydrate. The synthesized AuNPs reveal excellent catalytic function in the degradation (up to 99%) of azo-dyes. The kinetics study in the degradation reaction revealed that the technique could be extended to real wastewater treatment applications.

Electroceutical Silk-Silver Gel to Eradicate Bacterial Infection

With more than 50% of bacteria resistant to standard antibiotics, new strategies to treat bacterial infection and colonization are needed. Based on the concept of targeting the bacteria synergistically on various fronts, it is hypothesized that an electrical insult associated with antibacterial materials may be a highly effective means of killing bacteria. In this work, an injectable conductive gel based on silk fibroin (SF) and silver nanoparticles (Ag-NPs) is synthesized, capable of coating a zone of injury, allowing the application of a low electrical current to decrease bacterial contamination. With a high conductivity of 1.5 S cm^-1 , SF/Ag-NPs gels killed 80% of Escherichia coli in 1 min, no toxicity toward Chinese hamster ovary cells is observed. The mechanism of an electrical composite gel combined with electrical wound therapy is associated with silver ion (Ag⁺ ) release, and reactive oxygen species (ROS) production. The findings in the present study show a similar Ag⁺ release for treatment with gels and the combined effect, whereas ROS generation is 50% higher when a small electrical current is applied leading to a broad bactericidal effect.

Biofunctionalization of Natural Fiber-Reinforced Biocomposites for Biomedical Applications

In the last ten years, environmental consciousness has increased worldwide, leading to the development of eco-friendly materials to replace synthetic ones. Natural fibers are extracted from renewable resources at low cost. Their combination with synthetic polymers as reinforcement materials has been an important step forward in that direction. The sustainability and excellent physical and biological (e.g., biocompatibility, antimicrobial activity) properties of these biocomposites have extended their application to the biomedical field. This paper offers a detailed overview of the extraction and separation processes applied to natural fibers and their posterior chemical and physical modifications for biocomposite fabrication. Because of the requirements for biomedical device production, specialized biomolecules are currently being incorporated onto these biocomposites. From antibiotics to peptides and plant extracts, to name a few, this review explores their impact on the final biocomposite product, in light of their individual or combined effect, and analyzes the most recurrent strategies for biomolecule immobilization.

A Novel Coloration of Polyester Fabric through Green Silver Nanoparticles (G-AgNPs@PET)

This paper reports a novel route for the coloration of polyester fabric with green synthesized silver nanoparticles (G-AgNPs@PET) using chitosan as a natural eco-friendly reductant. The formation of AgNPs was confirmed by UV-visible spectroscopy. The morphologies and average particles size of G-AgNPs was investigated by transmission electron microscope (TEM) analysis. The uniform deposition of G-AgNPs on the PET fabric surface was confirmed with scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. The thermal properties were investigated using a thermogravimetric analyzer (TGA). The coloration and fastness properties of fabric were found to be significantly improved, a result related to the surface plasmon resonance of G-AgNPs. The antibacterial properties of fabric were also found to be excellent as more than 80% bacterial reduction was noticed even after 10 washing cycles. Overall, the proposed coating process using green nanoparticles can contribute to low-cost production of sustainable textiles.

Multifunctional Flax Fibres Based on the Combined Effect of Silver and Zinc Oxide (Ag/ZnO) Nanostructures

Cellulosic fibre-based smart materials exhibiting multiple capabilities are getting tremendous attention due to their wide application areas. In this work, multifunctional flax fabrics with piezoresistive response were developed through the combined functionalization with silver (Ag) and zinc oxide (ZnO) nanoparticles (NPs). Biodegradable polyethylene glycol (PEG) was used to produce AgNPs, whereas ZnONPs were synthetized via a simple and low-cost method. Flax fabrics with and without NPs were characterized by Ground State Diffuse Reflectance (GSDR), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and Thermogravimetric analysis (TGA). After creating a conductive surface by flax functionalization with AgNPs, ZnONPs were synthetized onto these fabrics. The developed fibrous systems exhibited piezoresistive response and the sensor sensitivity increased with the use of higher ZnO precursor concentrations (0.4 M). Functionalized fabrics exhibited excellent antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, higher hydrophobicity (WCA changed from 0⁰ to >100⁰), UV radiation resistance, and wash durability. Overall, this work provides new insights regarding the bifunctionalization of flax fabrics with Ag/ZnO nanostructures and brings new findings about the combined effect of both NPs for the development of piezoresistive textile sensors with multifunctional properties.

Preparation of Conductive Polyester Fibers Using Continuous Two-Step Plating Silver

Polyester fibers are used in various fields, due to their excellent mechanical and chemical stability. However, the lack of conductivity limits their application potential. In order to prepare conductive polyester fibers, silver is one of the most widely used materials to coat the surface of the fibers. This work aimed to prepare silver-coated polyester fibers by a continuous two-step method, which combined the operations of continuous electroless plating and electroplating. Meanwhile, we designed specialized equipment for the continuous plating of silver on the polyester fibers under a dynamic condition. The mechanical property, washability, electrical resistivity, and electrical conductivity of the resultant conductive polyester fibers obtained from different silver-plating conditions were also characterized. The results demonstrated that the conductive fibers prepared by continuous two-step silver plating equipment, had good electrical conductivity with better mechanical properties and washability.