Abstract

The design of artificial models of biomineralization has resulted in the union of inorganic materials research and supramolecular organic chemistry. To begin unraveling the biological mechanisms of mineralization, and, in doing so, create new types of materials, there is interest in the design of supramolecular, organic assemblies to alter the growth of inorganic crystals. In this seminar, I will describe the application of a matrix composed of an agarose hydrogel on top of a carboxylate-terminated self-assembled monolayer (SAM) to control the nucleation and growth of calcite crystals. The design of this matrix is based upon examples from biomineralization in which hydrogels are coupled with functionalized, organic surfaces to control, simultaneously, crystal morphology and orientation. In the synthetic system, calcite crystals nucleate from the (012) plane (the same plane that is observed in solution growth). The aspect ratio (length/width) of the crystals decreases from 2.1 ± 0.22 in solution to 1.2 ± 0.04 in a 3 wt% agarose gel. One possible explanation for the change in morphology is the occlusion of gel fibers inside of the crystals during the growth process. Etching of the gel-grown crystals with distilled water reveals an interpenetrating network of gel fibers and crystalline material. We are currently investigating the mechanism of occlusion and the structure and mechanical properties of the composite material. This work begins to provide insight into why organisms use hydrogels to control the growth of crystals.