Photo-assisted green synthesis of silver doped silk fibroin/carboxymethyl cellulose nanocomposite hydrogels for biomedical applications.

Silver nanoparticles (AgNPs) and regenerated silk fibroin (RSF) have recently attracted significant interests for their potential applications in preventing wound-related infections and in tissue engineering. Indeed, nano-silver has long been recognized as one of the most effective antimicrobial agents, and silk fibroin is well known for its capability of stimulating cell activities and facilitating tissue regeneration. In this study, a green synthesis approach was used to create a composite hydrogel (CoHy) of RSF stabilized with CarboxymethylCellulose-Na (CMC-Na) and loaded with AgNPs. Their swelling ratios were up to 59 g/g when tested in different physiologically relevant fluids. Material characterizations by Scanning electron microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), and X-Ray Diffraction (XRD) confirmed the presence of AgNPs on the surface. Antimicrobial properties of the CoHy samples were evaluated using agar diffusion tests. The results showed distinct inhibition zones against major microorganisms found in wound infections, including Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis), Methicillin Resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa (P. aeruginosa), Candida albicans (C. albicans) and Fluconazole-resistant Candida albicans (FRCA). Cytocompatibility studies with rat bone marrow derived mesenchymal stem cells (BMSCs) in vitro showed that the adhesion density of BMScs on the CoHy loaded with 1 mg/mL was similar to the cell-only control group for the first 24 h of culture; moreover, higher cell proliferation was observed on the CoHy without AgNPs, indicating the regenerative potentials of the RSF/CMC composite hydrogels.

In-situ photo-assisted deposition of silver particles on hydrogel fibers for antibacterial applications.

Silver nanoparticles (AgNPs) have attracted intensive research interest and have been recently incorporated in polymers, medical devices, hydrogels and burn dressings to control the proliferation of microorganisms. In this study a novel silver antibacterial coating was deposited for the first time on hydrogel fibers through an in-situ photo-chemical reaction. Hydrogel blends obtained by mixing different percentages of silver-treated and untreated fibers were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four different fluids, such as phosphate buffered saline (PBS), simulated body fluid (SBF), chemical simulated wound fluid (cSWF), and deionized water (DI water), were used for evaluating the swelling properties. The results obtained confirmed that the presence of silver did not affect the properties of the hydrogel. Moreover, the results obtained through inductively coupled plasma mass spectrometry (ICP-MS) demonstrated very low silver release values, thus indicating the perfect adhesion of the silver coating to the substrate. Good antibacterial capabilities were demonstrated by any hydrogel blend on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) through agar diffusion tests and optical density readings.