Antimicrobial and antioxidant surface modification toward a new silk-fibroin (SF)-l-Cysteine material for skin disease management

Abstract A novel dressing material – silk fibroin fabric (SF)- l -Cysteine ( l -Cys) – is here developed to be used as standard treatment for atopic dermatitis (AD), which combines comfort, thermic, and tensile strength properties of silk materials with antioxidant and antimicrobial effects of l -Cys. A careful understanding about the linking strategies is needed in order not to compromise the bioavailability of l -Cys and deplenish its bioactivity. Durability was also addressed through washing cycles and compared with hospital requirements, according to international Standard EN ISO 105-C06:2010. The present research also analyze the interactions between Staphylococcus aureus and SF- l -Cys under simulating conditions of AD and demonstrated the effectiveness of a double covalent grafting, with the importance of SF tyrosine (Tyr) covalent linkage with l -Cys (SF-g- l -Cys/Tyr-g- l -Cys) even after several washing cycles, twenty five, whereas for a disposable application a single covalent mechanism of grafting l -Cys proved to be sufficient (SF-g- l -Cys). Results showed effective antimicrobial activities exhibiting higher inhibition ratios of 98.65% for SF-g- l -Cys after 5 washing cycles, whereas 97.55% for SF-g- l -Cys/Tyr-g- l -Cys after 25 washing cycles, both at pH 9.5 grafting strategy. Furthermore, it is also reported a non-protumoral effect of l -Cys. A new advance is herein achieved at the world of medical antimicrobial textiles tailored to address wound moisture environment and exudate self-cleaning, which may open novel applications as complementary therapy for AD disease.