Patterned crystallization of calcite in vivo and in vitro

Biologically formed calcite crystals have unique, sculptured shapes that are believed to be regulated locally by specific macromolecules and by directional flux of ions into the microenvironment of crystal growth. This paper describes a biologically inspired synthesis of patterned calcitic films using micropatterned self-assembled monolayers (SAMs) which served as spatially constrained microenvironments for crystallization. The approach is based on the ability to govern mass transport to different regions of the surface at a micron scale, by patterning rapidly nucleating regions (carboxylate-terminated SAMs) in regions that art: slowly nucleating (methyl-terminated SAMs) and by regulating their sizes, geometry and concentration of the crystallizing solution. The ion flux into the regions of crystal growth keeps the crystallizing solution over slowly nucleating regions undersaturated. Crystallization is then entirely restricted to the carboxylate-terminated regions of SAMs and results in the formation of large-area, high-resolution inorganic replicas of the underlying organic patterns. (C) 2000 Elsevier Science B.V. All rights reserved.