Achieving coalesced breathability, mechanical and shape memory properties of collagen fibrous matrix through complexing with chromium (III)

Abstract

Protein materials evolved in nature for millions of years can display critical structural and functional properties which is difficult for synthetic polymers to surpass. Hence, the combination of multiple components or hierarchies from natural source through a facile method may stand out as a forerunner to materials design and application. Inspired from metalloprotein, this study reported an organic-metal biosystem based on chromium (III) complexed collagen fibrous matrix (Cr-CFM). The obtained Cr-CFM retains inherent conformation of collagen and its fiber morphology in the skin. Compared with pristine CFM, Cr-CFM showed enhanced waterproofness and breathability. Due to coexistence of hydrogen bonds and newly introduced chromium (III) complexing linkages, Cr-CFM exhibited water-adaptive mechanical property. In this organic-metal biosystem, hydrogen bonds show reversible cleavage-reformation under water interference while chromium (III) complexing linkages remains stable. Such combination of “switch” and “netpoint” facilitated water responsive shape memory ability of Cr-CFM with shape fixation and recovery reaching over 80%. The reveal of relationship between structure and coalesced properties of Cr-CFM herein is believed to promote progress of smart protein materials and give inspirations to synthetic polymers.