Amyloid Fibrils form Hybrid Colloidal Gels and Aerogels with Dispersed CaCO3 Nanoparticles

5 years ago

Amyloid Fibrils form Hybrid Colloidal Gels and Aerogels with Dispersed CaCO3 Nanoparticles

Gustav Nyström, Raffaele Mezzenga, Yi Shen

New hybrid colloidal gels are reported formed by amyloid fibrils and CaCO3 nanoparticles (CaNPs), with Ca2+ as charge screening ions and CaNPs as physical crosslinking agents to establish and stabilize the network. The gel is characterized by rheological measurements and diffusing wave spectroscopy, complemented by microscopic observations using transmission and scanning electron microscopy. The hybrid colloidal gels show a two orders of magnitude improved gel strength at significantly shorter gelation times compared to previous calcium ion-induced amyloid fibril gels. Supercritical CO2-dried colloidal aerogels allow demonstrating that amyloid fibrils, combined with smaller (higher specific surface area) CaNPs, constitute a denser fibrils network, resulting in stronger gels. By varying the amyloid fibril concentration and the CaNPs size and concentration, the complete phase diagram is mapped out. This enables identifying the sol–gel phase transition and a window for gel formation, which widens with increasing CaNPs size. Finally pH responsiveness and self-healing properties of this hybrid colloidal gel are also demonstrated, making these systems a suitable candidate for biological applications. This study describes a new strategy to form hydrogels and aerogels based on beta-lactoglobulin fibrils and calcium carbonate nanoparticles (CaNPs). By dispersing and dissolving CaNPs in beta-lactoglobulin fibril solutions, calcium ions and CaNPs act as charge screeners and crosslinkers, respectively, leading to stable gel networks. The resulting gels show high mechanical strengths and pH-sensitive self-healing properties, opening novel opportunities for biological and pharmaceutical applications.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adfm.201700897