Enzymatically controlled material design with casein--from defined films to localized deposition of particles

A new concept for deposition and material design of coatings from biological compounds is presented. An enzymatic reaction triggers the specific coagulation of particles on a support surface. The first examined model system is casein and is based on the natural rennet reaction as applied in the process of cheese-making. The aspartic protease chymosin is immobilized on a support surface and cleaves the hydrophilic parts of the casein micelles, inducing deposition. The concept allows for a high level of control over film characteristics and enables the formation of site-specific film structures. The variability rages from formation of casein films with several micrometers film thickness to the targeted deposition of casein micelles.