Molecularly imprinted polymers fabricated via Pickering emulsions stabilized solely by food-grade casein colloidal nanoparticles for selective protein recognition.

Abstract

Novel molecularly imprinted polymers (MIPs) based on denatured casein nanoparticle (DCP)-stabilized Pickering emulsions were developed for the first time. Casein, a phosphoprotein, is the main protein in milk. In this work, DCPs were solely used as Pickering-type interfacial emulsifiers for fabrication of MIPs for the selective recognition of proteins for the first time. DCPs were prepared by acidification and heat denaturation (at 80 °C) of casein. Their dispersions have satisfactory colloidal stability over a wide pH range. The DCPs acted as natural, food-grade, and edible interfacial emulsifiers, and adsorbed at the oil-water interface to form Pickering emulsions. After the polymerization of monomers, the template protein was removed by elution. During the elution, the interfacial DCPs were also removed, allowing more imprinted cavities to become exposed. The interfacial imprinting technology causes nearly all the imprinted sites to locate on the surface of the polymeric material. Therefore, the MIPs obtained exhibit fast rebinding and excellent specific recognition ability toward the analytes. Overall, this work provides a promising method for designing and fabricating natural-protein-based structured emulsions to prepare MIPs and thus offers new insight into protein separation and purification. Graphical Abstract Pickering emulsions stabilized by denatured casein particles.