Transdermal Silk-Recombinant Collagen Nanocomplexes with Synergistic Bioactivity

Hydrophilic macromolecules with versatile bioactivities have potential in regenerative medicine and cosmetics but are limited by their inferior transdermal capacity. Here, inspired by the transdermal capacity of silk nanofibers (SNF), recombinant collagen XVII (RCL), a model of hydrophilic macromolecules, was assembled with SNFs to form nanocomplexes. The nanostructures and sizes of the complexes could be controlled through changing the ratio of SNF and RCL, which then resulted in various transdermal capacities. Although RCL retained nonpermeable behaviors, the nanocomplexes with optimal ratios of SNF and RCL showed a desirable transdermal capacity and skin barrier-repairing capacity. Better bioactivity was also achieved for the SNF-RCL nanocomplexes, suggesting desirable synergistic action. In the in vivo study, topical application of the nanocomplex gels promoted tissue healing of the photodamaged skin, superior to that treated with pure RCL and SNF. It is suggested that the SNFs could form transdermal nanocomplexes with hydrophilic macromolecules without the compromise of bioactivities, implying the potential of developing SNF-hydrophilic macromolecules' transdermal delivery systems for skin disease.