Nanocellulose-Assisted Thermally Induced Growth of Silver Nanoparticles for Optical Applications

Nanocomposite Based on Bacterial Cellulose and Silver Nanoparticles Improve Wound Healing Without Exhibiting Toxic Effect

Wound healing is an important and complex process, containing a multifaceted process governed by sequential yet overlapping phases. Certain treatments can optimize local physiological conditions and improve wound healing. Silver nanoparticles (AgNP) are widely known for their antimicrobial activity. On the other hand, bacterial cellulose (BC) films have been used as a dressing that temporarily substitutes the skin, offering many advantages in optimizing wound healing, in addition to being highly biocompatible. Considering the promising activities of AgNP and BC films, the present study aimed to evaluate the wound healing activity in Wistar Hannover rats using a nanocomposite based on bacterial cellulose containing AgNP (AgBC). In a period of 21 days, its influence on the wound area, microbial growth, histopathological parameters, and collagen content were analyzed. In addition, toxicity indicators were assessed, such as weight gain, water consumption, and creatinine and alanine transaminase levels. After 14 days of injury, the animals treated with AgBC showed a significant increase in wound contraction. The treatment with AgBC significantly reduced the number of microbial colonies compared to other treatments in the first 48 h after the injury. At the end of the 21 experimental days, an average wound contraction rate greater than 97 % in relation to the initial area was observed, in addition to a significant increase in the amount of collagen fibers at the edge of the wounds, lower scores of necrosis, angiogenesis and inflammation, associated with no systemic toxicity. Therefore, it is concluded that the combination of preexisting products to form a new nanocomposite based on BC and AgNP amplified the biological activity of these products, increasing the effectiveness of wound healing and minimizing possible toxic effects of silver.

Recycling of silver nanoparticles from electronic waste via green synthesis and application of AgNPs-chitosan based nanocomposite on textile material

The main thrust of this project is the fabrication of silver nanoparticles (AgNPs) from electronic waste (PCB board) and applying it on 100% cotton fabric as an antimicrobial agent. The nanoparticle formation of silver was done by green synthesis way using an aqueous leaf extract of Eichhornia crassipes. Furthermore, chitosan was also applied to the fabric with silver nanoparticles by coating. FTIR and SEM tests characterized the fabricated silver nanoparticles, and antimicrobial tests were followed by the disc diffusion method. The SEM analysis showed an average particle size of 76.91 nm. The FTIR analysis showed the successful reduction of silver nanoparticles and the bonding with chitosan and cellulose. Besides, the EDX reports confirmed the existence of AgNPs by indicating a strong signal in the silver region. In addition, SEM characteristics analysis confirmed the uniform deposition of silver nanoparticles. Finally, the antimicrobial property was tested against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The antimicrobial result was found satisfactory in the case of green-synthesized recycled AgNPs. However, the effectiveness was not observed to be higher than green-synthesized pure AgNPs. In this study, the zone of inhibition of AgNPs was also compared to the reference antibiotics Ciprofloxacin.

Mapping the Progress in Surface Plasmon Resonance Analysis of Phytogenic Silver Nanoparticles with Colorimetric Sensing Applications

Nanotechnology is gaining enormous attention as the most dynamic research area in science and technology. It involves the synthesis and applications of nanomaterials in diverse fields including medical, agriculture, textiles, food technology, cosmetics, aerospace, electronics, etc. Silver nanoparticles (AgNPs) have been extensively used in such applications due to their excellent physicochemical, antibacterial, and biological properties. The use of plant extract as a biological reactor is one of the most promising solutions for the synthesis of AgNPs because this process overcomes the drawbacks of physical and chemical methods. This review article summarizes the plant-mediated synthesis process, the probable reaction mechanism, and the colorimetric sensing applications of AgNPs. Plant-mediated synthesis parameters largely affect the surface plasmon resonance (SPR) characteristic due to the changes in the size and shape of AgNPs. These changes in the size and shape of plant-mediated AgNPs are elaborately discussed here by analyzing the surface plasmon resonance characteristics. Furthermore, this article also highlights the promising applications of plant-mediated AgNPs in sensing applications regarding the detection of mercury, hydrogen peroxide, lead, and glucose. Finally, it describes the future perspective of plant-mediated AgNPs for the development of green chemistry.

A Versatile Strategy for the Fabrication of Poly(ethyl methacrylate) Composites

Poly(ethyl methacrylate) (PEMA) is dissolved in ethanol, known to be a non-solvent for PEMA, due to the solubilizing ability of an added bile acid biosurfactant, lithocholic acid (LA). The ability to avoid traditional toxic and carcinogenic solvents is important for the fabrication of composites for biomedical applications. The formation of concentrated solutions of high molecular weight PEMA is a key factor for the film deposition using the dip coating method. PEMA films provide corrosion protection for stainless steel. Composite films are prepared, containing bioceramics, such as hydroxyapatite and silica, for biomedical applications. LA facilitates dispersion of hydroxyapatite and silica in suspensions for film deposition. Ibuprofen and tetracycline are used as model drugs for the fabrication of composite films. PEMA-nanocellulose films are successfully prepared using the dip coating method. The microstructure and composition of the films are investigated. The conceptually new approach developed in this investigation represents a versatile strategy for the fabrication of composites for biomedical and other applications, using natural biosurfactants as solubilizing and dispersing agents.

Metallized Skeleton of Polymer Foam Based on Metal-Organic Decomposition for High-Performance EMI Shielding

Highly conductive polymer foam with light weight, flexibility, and high-performance electromagnetic interference (EMI) shielding is highly desired in the fields of aerospace, communication, and high-power electronic equipment, especially in the board-level packaging. However, traditional technology for preparing conductive polymer foam such as electroless plating and electroplating involves serious pollution, a complex fabrication process, and high cost. It is urgent to develop a facile method for the fabrication of highly conductive polymer foam. Herein, we demonstrated a lightweight and flexible silver-wrapped melamine foam (Ag@ME) via in situ sintering of metal-organic decomposition (MOD) at a low temperature (200 °C) on the ME skeleton modified with poly(ethylene imine). The Ag@ME with a continuous 3D conductive network exhibits good compressibility, an excellent conductivity of 158.4 S/m, and a remarkable EMI shielding effectiveness of 63 dB in the broad frequency of 8.2-40 GHz covering X-, Ku-, K-, and Ka-bands, while the volume content is only 2.03 vol %. The attenuation mechanism of Ag@ME for EM waves is systematically investigated by both EM simulation and experimental analysis. Moreover, the practical EMI shielding application of Ag@ME in board-level packaging is demonstrated and it shows outstanding near-field shielding performance. This novel strategy for fabrication of highly conductive polymer foam with low cost and non-pollution could potentially promote the practical applications of Ag@ME in the field of EMI shielding.