Gellan gum-dopamine mediated in situ synthesis of silver nanoparticles and development of nano/micro-composite injectable hydrogel with antimicrobial activity

Infected skin wounds represent a serious health threat due to the long healing process and the risk of colonization by multi-drug-resistant bacteria. Silver nanoparticles (AgNPs) have shown broad-spectrum antimicrobial activity. This study introduces a novel approach to address the challenge of infected skin wounds by employing gellan gum-dopamine (GG-DA) as a dual-functional agent, serving both as a reducing and capping agent, for the in situ green synthesis of silver nanoparticles. Unlike previous methods, this work utilizes a spray-drying technique to convert the dispersion of GG-DA and AgNPs into microparticles, resulting in nano-into-micro systems (AgNPs@MPs). The microparticles, with an average size of approximately 3 μm, embed AgNPs with a 13 nm average diameter. Furthermore, the study explores the antibacterial efficacy of these AgNPs@MPs directly and in combination with other materials against gram-positive and gram-negative bacteria. The versatility of the antimicrobial material is showcased by incorporating the microparticles into injectable hydrogels. These hydrogels, based on oxidized Xanthan Gum (XGox) and a hyperbranched synthetic polymer (HB10K-G5-alanine), are designed with injectability and self-healing properties through Shiff base formation. The resulting nano-into-micro-into-macro hybrid hydrogel emerges as a promising biomedical solution, highlighting the multifaceted potential of this innovative approach in wound care and infection management.

Photochemical Synthesis of Gold and Silver Nanoparticles-A Review

Nanomaterials have supported important technological advances due to their unique properties and their applicability in various fields, such as biomedicine, catalysis, environment, energy, and electronics. This has triggered a tremendous increase in their demand. In turn, materials scientists have sought facile methods to produce nanomaterials of desired features, i.e., morphology, composition, colloidal stability, and surface chemistry, as these determine the targeted application. The advent of photoprocesses has enabled the easy, fast, scalable, and cost- and energy-effective production of metallic nanoparticles of controlled properties without the use of harmful reagents or sophisticated equipment. Herein, we overview the synthesis of gold and silver nanoparticles via photochemical routes. We extensively discuss the effect of varying the experimental parameters, such as the pH, exposure time, and source of irradiation, the use or not of reductants and surfactants, reagents' nature and concentration, on the outcomes of these noble nanoparticles, namely, their size, shape, and colloidal stability. The hypothetical mechanisms that govern these green processes are discussed whenever available. Finally, we mention their applications and insights for future developments.

Methods of Gold and Silver Nanoparticles Preparation

The versatile family of nanoparticles is considered to have a huge impact on the different fields of materials research, mostly nanoelectronics, catalytic chemistry and in study of cytocompatibility, targeted drug delivery and tissue engineering. Different approaches for nanoparticle preparation have been developed, not only based on "bottom up" and "top down" techniques, but also several procedures of effective nanoparticle modifications have been successfully used. This paper is focused on different techniques of nanoparticles' preparation, with primary focus on metal nanoparticles. Dispergation methods such as laser ablation and vacuum sputtering are introduced. Condensation methods such as reduction with sodium citrate, the Brust-Schiffrin method and approaches based on ultraviolet light or biosynthesis of silver and gold are also discussed. Basic properties of colloidal solutions are described. Also a historical overview of nanoparticles are briefly introduced together with short introduction to specific properties of nanoparticles and their solutions.

A facile method to synthesize small-sized and superior crystalline Cs0.32WO3 nanoparticles for transparent NIR shielding coatings

Small-sized and superior crystalline Cs_0.32WO₃ nanoparticles used for NIR-shielding were developed by tailoring the molar ratio of Cs/W.