Fabrication of chitosan colloidal gels via pH-mediated self-association

The development of biopolymer-based colloidal systems is of great interest in the food science and pharmaceutical fields. Here, we report a simple process to fabricate chitosan colloidal gels though self-assembly of chitosan in solution. In the first step, insoluble chitosan aggregates formed at close to neutral pH (6.6–7.0) were transformed into nano-sized particles (20–100 nm) via shear homogenization. These nanoparticles then spontaneously aggregated and assembled to form a 3D space-spanning network upon storage. The chitosan particle size as well as the formation, viscoelasticity and microstructure of the corresponding gels were highly affected by pH. Findings from this study are of interest for the fabrication of tunable colloidal gel materials using chitosan alone.