From by-products to biomaterials for active wound dressings

Innovative multifunctional biomaterials should properly improve the performance of wound dressings by promoting tissue healing while preventing side events such as bacterial infection and excessive inflammation. Moreover, the sustainable design of new materials can result in environmentally friendly and cost-effective solutions. However, very few of the available dressings satisfy all of these characteristics, and none are derived from a renewable source. Herein, bioactive compounds obtained from industrial by-products were applied to develop active wound dressings that combine antioxidant and antibacterial activities, combining multifunctionality and a sustainable approach. Accordingly, the fabric was obtained by electrospun keratin nanofibers (NF) obtained from discarded wool, while bioactivity was introduced through NF functionalization with polyphenols-rich extracts from pomegranate and grape by-products. Keratin fabrics were checked by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR) confirming the stability of the NF random structure, while extracts were analyzed by UV-Vis and HPLC demonstrating the presence of bioactive phenols such as punicalagin, ellagic acid and catechins. NF functionalization was confirmed by Zeta potential and Folin&Ciocalteu, as well as phenols antioxidant activity was verified by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing/antioxidant power (FRAP) and cupric reducing antioxidant capacity (CUPRAC) assays. Afterward, a preliminary biological characterization revealed that the dressings were cytocompatible towards human fibroblasts (>90% viability), as well as the NF functionalization reported a significant (p < 0.05) scavenger activity preventing the intracellular internalization of toxic ROS active species (>90% reduction). Finally, pomegranate functionalization significantly (p < 0.05) prevented surface contamination by Staphylococcus epidermidis of > 95% compared to non-functionalized NF, as well it successfully reduced the infection in situ after being released from the dressing.