Crystallization in patterns: A bio-inspired approach

Nature produces a wide variety of exquisite, highly functional mineralized tissues using simple inorganic salts. Biomineralization occurs within specific microenvironments, and is finely tuned by cells and specialized biomacromolecules. This article surveys bio-inspired approaches to artificial crystallization based on the above concept: that is, the use of organized organic surfaces patterned with specific initiation domains on a submicrometer scale to control patterned crystal growth. Specially tailored self-assembled monolayers (SAMs) of to-terminated alkanethiols were micropatterned on metal films using soft lithography and applied as organic templates for the nucleation of calcium carbonate. Crystallization results in the formation of large-area, high-resolution inorganic replicas of the underlying organic patterns. SAMs provide sites for ordered nucleation, and make it possible to control various aspects of the crystallization process, including the precise localization of particles, nucleation density, crystal sizes, crystallographic orientation, morphology, polymorph, stability, and architecture. The ability to construct periodic arrays of uniform oriented single crystals, large single crystals with controlled microporosity, or films presenting patterns of crystals offers a potent methodology to materials engineering.