Thermoresponsive antimicrobial wound dressings via simultaneous thiol-ene polymerization and in situ generation of silver nanoparticles† Zahra Abdali, a Hamid Yeganeh, * b Atefeh Solouk, a Reza Gharibi b and Marziyeh Sorayya b 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. Introduction Wound dressings are an important section of the medical and pharmaceutical wound care market worldwide. Wound dress- ings are designed to facilitate the natural healing process. In fact, wound healing is a dynamic process consisting of several cellular and biochemical activities and overlapping phases including inammation, new tissue formation, and remodel- ing. 1,2 Unfortunately, the human body cannot heal dermal injuries completely. Since skin forms a protective barrier around the body, damage to the dermis may cause several problems like severe dehydration as well as infection. There- fore, using wound dressings is mandatory for the promotion of rapid wound healing with the best functional and cosmetic results. 3 For this purpose, wound dressings should have proper cytocompatibility, appropriate exibility, gas permeability, durability, and more importantly the ability to manage exudates to prevent scab and scar formation on wounded area. Mean- while, non-adherence to wound bed and prevention from bacterial/fungal infection of damaged tissues are two key features of versatile modern wound dressings. 4 To prepare wound dressings having the most of aforemen- tioned features, selection of materials used for the preparation of dressings and mode of their fabrication have prime impor- tance. Polyurethane framework was selected in the present study as the basic ingredient of target dressings. The primary reason for this selection is long and established history for application of polyurethane for the preparation of dressing membranes. This interest to polyurethane is attributed to excellent physico-mechanical and biological properties of polyurethanes. 4–6 During healing process the volume of wound exudates reduces gradually, therefore, the tendency for adherence of dressing to wound increases, consequently, removal of dressing from wound bed is painful and may cause secondary injury. 7,8 One accepted methodology for imparting cell adhesion control and easy peeling characteristic in wound dressings is utilization of thermoresponsive materials. Poly(N-isopropylacrylamide) a Biomedical Engineering Faculty, Amirkabir University of Technology, Tehran, Iran b Iran Polymer and Petrochemical Institute, P.O. Box: 14945/115, Tehran, Iran. E-mail: h.yeganeh@ippi.ac.ir † Electronic supplementary information (ESI) available. See DOI: 10.1039/c5ra11618j Cite this: RSC Adv. , 2015, 5, 66024 Received 17th June 2015 Accepted 29th July 2015 DOI: 10.1039/c5ra11618j www.rsc.org/advances 66024 | RSC Adv., 2015, 5, 66024–66036 This journal is © The Royal Society of Chemistry 2015 RSC Advances PAPER