Colloids of pure proteins by hard templating

Colloidal particles from pure proteins are favorable over composite colloids (usually polymer-based) for applications in drug delivery and biocatalysis. This is due to degradation issue and protein unfolding. Hard templating based on porous CaCO3 cores has been recently adopted for fabrication of pure protein colloids. In comparison to conventional techniques, the templating offers (i) a control over particles size and (ii) mild preparation conditions without any additives, shear forces, and exposure to high temperature or gas-water interface. In this review, the current achievements in CaCO3-based templating of protein colloids are given. The focus is on physicochemical and material properties of the colloids such as stability, mechanical properties, and internal structure. These properties are considered as a function of pH, ionic strength, and protein denaturation degree. Understanding of these basic aspects gives an option to formulate the protein colloids by hard templating achieving desired particle properties that is crucially important for future applications.