Role of soluble polymers on the preparation of functional thin films of calcium carbonate

The emerging science of nanobiotechnology relies on the observation that, through evolution, nature has produced highly complex nanostructures using macromolecules, especially nucleic acids, polysaccharides and proteins. Understanding the molecular mechanism of how these macromolecules interact to produce nanostructures is the key to the biomimetic materials design and synthesis. Calcium carbonate (CaCO3)-based biominerals such as nacre of mollusk shells have complex and hierarchal architectures on submicrometer length scales. The fabrication of such composite materials with control over the shape and properties can be achieved by adopting the natural process of template-driven biomineralization. Our strategy is to obtain nanostructured thin films of CaCO3 by tuning the chemical structures of organic matrices. Herein, we report the fabrication of functional thin films of aragonite, vaterite and calcite by a template-driven mineralization of calcium carbonate over a functionalized natural scaffold such as demineralized eggshell membrane. The functionalized templates were generated by the pre-adsorption of various soluble polymers such as polyaspartic acid (PAsp), polyglutamic acid (PGlu) and aspartic acid incorporated polyacrylic acid (PA-Asp). These biocompatible calcium carbonate coatings might be useful for tissue engineering applications and also for fundamental studies of cell–matrix interactions.