No abstract

Hyaluronic acid (HA), as a safe biomaterial with minimal immunogenicity, is being employed in a broad range of medical applications. Since unmodified HA has a high potential for biodegradation in the physiological condition, herein, an HA-based cross-linked hydrogel was formulated using polydimethylsiloxane-diglycidyl ether terminated (PDMS-DG) via epoxide-OH reaction. The formation of HA-PDMS hydrogel was confirmed using FTIR, NMR, and FESEM. Temperature demonstrated a critical role in the physicochemical properties of the final products. Gel-37, which formed at 37 C, had a higher modification degree (MD) and more stability against hyaluronidase and oxidative stress than the hydrogel formulated at 25 C (Gel-25). In addition, the swelling ratio, roughness, and porous network topology of Gel-25 and Gel-37 were different. The rheology measurement indicated that HA-PDMS hydrogel had a stable viscoelastic character. The hydrogel was also biocompatible, noncytotoxic, and considerably stable during 7-months storage. Overall, various determined parameters confirmed that HA-PDMS hydrogel is worth using in different medical applications.

In this study, novel hydrogels based on polyurethane/polyethylene glycol (PU/PEG) and their silver nanocomposites (PU/PEG/Ag x, x = 100, 200, 400, and 800) were developed using click chemistry and a green method. Mechanical analysis showed that introducing of silver nanoparticles (AgNPs) into hydrogels and increasing the content increased their mechanical properties dramatically. Tensile strength and elongation at break increased from 0.2 MPa and 105% for PU/PEG to 2.5 MPa and 210% for PU/PEG/Ag 800. Similarly, the compressive strength increased from 5 to 55 MPa. Investigation of the SEM images showed that the AgNPs were homogeneously dispersed throughout the hydrogel network, and through the incorporation of silver nanoparticles in hydrogels, the pore size of hydrogels decreased. Therefore, the swelling degree of hydrogels decreased by increasing the content of AgNPs. FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS) demonstrated that the interaction of network heteroatoms with AgNPs was responsible for stabilizing silver nanoparticles. The antibacterial properties of nanocomposites were evaluated against Pseudomonas aeruginosa and Staphylococcus aureus bacteria. These nanocomposites showed significant activities against S. aureus bacteria. In addition, the cell viability test showed that these nanocomposites had good biocompatibility (84% cells viable). Therefore, they could be favorable candidates for wound dressing applications.