Thermoresponsive antimicrobial wound dressings via simultaneous thiol-ene polymerization and in situ generation of silver nanoparticles

Thiol-ene polymerization and a one electron transfer reaction were simultaneously utilized in the present study for the preparation of semi-IPNs composed of a thermoplastic polyurethane elastomer, crosslinked poly(N-isopropylacrylamide) and silver nanoparticles (AgNPs). Application of these materials as thermoresponsive and antibacterial wound dressings with proper mechanical properties, efficient handling of wound exudates and easy peeling from the wounded area were examined. The thermoresponsivity of the membranes was elucidated via differential scanning calorimetry and measuring water absorption at different temperatures. Ease of removal of the designed dressings from the wound bed was confirmed based on qualitative examination of adhered cells to the dressings at temperatures lower and higher than the lower critical solution temperature of the prepared membranes. The proper bulk hydrophilicity and water vapour transmission rate of designed dressings showed their ability for managing of wound exudates. The potential ability of prepared dressings for protection of the wound bed from external forces over the entire period of healing was confirmed by their excellent tensile properties even at a fully hydrated state. In situ generation and dispersion of AgNPs into the matrix of the dressings, as well as the size of these particles were elucidated by EDX and TEM methods. An MTT assay against human dermal fibroblast cells performed on dressings with and without AgNPs approved their appropriate cytocompatibility. And finally, the measured antimicrobial activity of the dressings against different Gram positive and Gram negative bacteria as well as a fungal strain showed promising efficiency of impregnated AgNPs for combating microorganisms.