One-pot synthesis of silver-based chitosan macromolecular hydrogels and its antimicrobial activity

This study focused on the description of a new methodology for preparing AgNP-loaded chitosan-based hydrogels via a one-pot procedure through the thermal decomposition of urea. This new methodology enhanced the controlled production of AgNPs by increasing the viscosities of the polymeric solutions and controlling the pH basification, thereby favoring nanoparticle nucleation over aggregation, resulting in the production of AgNPs with sizes lower than 20 nm. Four types of chitosan samples, including two native samples with different molecular weights and their sulfated salts, were studied. AgNPs synthesis was characterized following Surface Plasmon Resonance and by TEM microscopy, while simultaneous hydrogel formation was followed by viscometry. The synthesized AgNPs were pseudospherical in shape with a narrower distribution and smaller size for those samples produced with chitosan salts. The AgNPs-chitosan samples exhibited moderate antioxidant and antimicrobial activities against E. coli ATCC 25923 and S. aureus ATCC 25922 with inhibition zones of around 13 mm in the best formulations. These properties indicate the potential of these materials as wound-healing agents.