Engineered Hydrophobin for Biomimetic Mineralization of Functional Calcium Carbonate Microparticles

Abstract

In this study , the modified hydrophobin, engineered for biomimetic mineralization, has been employed as a structure-directing agent for mineralization of calcium carbonate. For the first time amphiphilic calcium car bonate particles have been obtained, using engineered proteins. The mineral microparticles have been charac terized by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). While miner alization in the presence of non-modified hydrophobin results in polymorph mineral structures, uniform micro spheres with an average particle diameter of one micron are obtained by employing hydrophobin which has been modified with an additional ceramophilic protein sequence. Owing to the tri-functionality of the modified hy drophobin (hydrophilic, hydrophobic and ceramophilic), the obtained mineral microparticles exhibit amphi philic properties. Potential applications are in the areas of functional fillers and pigments, like biomedical and composite materials. Pickering emulsions have been prepared as a demonstration of the emulsion-stabilizing properties of the obtained amphiphilic mineral microspheres. The structure-directing effects of the studied en gineered hydrophobins are compared with those of synthetic polymers ( i.e. polycarboxylates) used as crystalliza tion and scaling inhibitors in industrial applications.