Polyurethane-silica hybrid foams from a one-step foaming reaction, coupled with a sol-gel process, for enhanced wound healing.

Polyurethane (PU)-based dressing foams have been widely used due to their excellent water absorption capability, optimal mechanical properties, and unequaled economic advantage. However, the low bioactivity and poor healing capability of PU limit the applications of PU dressings in complex wound healing cases. To resolve this problem, this study was carried out the hybridization of bioactive silica nanoparticles with PU through a one-step foaming reaction that is coupled with the sol-gel process. The hybridization with silica did not affect the intrinsically porous microstructure of PU foams with silica contents of up to 10wt% and where 5-60nm silica nanoparticles were well dispersed in the PU matrix, despite slight agglomerations. The incorporated silica enhanced the mechanical performance of PU by proffering better flexibility and durability as well as maintaining good water absorption capabilities and the WVTR characteristics of pure PU foam. The silica of PU-10wt% Si foams was gradually dissolved and released under physiological conditions during a 14-day immersion period. The in vitro cell attachment and proliferation tests showed significant improvements in terms of the biocompatibility of PU-Si hybrid foams and demonstrated the effects of silica on cell growth. More significantly, the superior healing capability of PU-Si as a wound dressing in comparison to PU-treated wounds was verified through in vivo animal tests. Full-thickness wounds treated with PU-Si foams exhibited faster wound closure rates as well as accelerated collagen and elastin fiber regeneration in newly formed dermis, which was ultimately completely covered by a new epithelial layer. It is clear that PU-Si hybrid foams have considerable potential as a wound dressing material geared for accelerated, superior wound healing.