Streptavidin-biotin was found to induce the aggregation of micrometer-sized calcite particles, and the optimum ligand-receptor surface tagging condition was found when monolayer coverage of the sample by the adsorbed ligand-receptor components was reduced to 80% coverage. The role of crystallography in the agglomeration process induced by the presence of surface-adsorbed ligand-receptor was also examined. This was achieved by using calcite exhibiting three different crystal habits: rhombohedral, hexagonal spindles, and triangular plates. The latter two habits express faces generated by anionic templates, and the topology of agglomerates suggests that the carboxyl group of the biotin and the streptavidin interacting with these surfaces generated a local variation in crystal packing. This was accounted for by simply relating the preferential interaction between the modified surface of the crystal and the high-affinity ligand complex on the functionality of additives used to template surfaces during crystal growth.
anion, biotin, calcium carbonate, ligand, receptor, streptavidin, binding affinity, chemical modification, chemical structure, crystal structure, crystallization