Self-aggregation of water-dispersible nanocollagen helices.

Inspired by nature, collagen is an outstanding polypeptide utilized to exploit its bioactivity and material design for healthcare technologies. In this study, we describe the self-aggregation of water-dispersible nanocollagen helices upon solidification to fabricate different forms of natural collagen materials. Chemically extracted native collagen fibrils are uniform anisotropic nanoparticles with an average diameter of about 50 nm and a high aspect ratio. The as-prepared collagen nanofibrils are soluble in sodium acetate-acetic acid buffer and are dispersible in water, thus generating collagen liquids that are used as distinct biopolymer precursors for materials development. Our interesting findings indicate that water-dispersible collagen-derived alcogels undergo critical point drying to self-arrange hierarchical nanofibrils into helix bundles in collagen sponge-like aerogels. Notably, using lyophilization to remove water in the biopolymer dispersion, a full regeneration of solidified fibers is achieved, producing collagen aerogels with lightweight characteristics similar to natural cottons. The self-aggregation of water-dispersible collagen occurs under freeze-drying conditions to turn individual nanofibrils into sheets with layered structures in the aerogel networks. The development of transparent, water resistant collagen bioplastic-like membranes was achieved by supramolecular self-assembly of water-dispersible collagen nanofibrils. Our efforts present a reliable concept in soft matter for creating promising collagen examples of liquids, hydrogels, aerogels, and membranes to increase utilization value of native collagen for biomedicine, pharmaceuticals, cosmetics, and nutrients.