Electrochemical Biomineralization: The Deposition of Calcite with Chiral Morphologies

The biominerals calcite and aragonite are electrodeposited by electrochemically generating base in a solution containing Ca 2+ and HCO 3 - . Although calcite crystallizes in the achiral space group R 3̄ c, orientations of calcite which lack mirror or glide plane symmetry are chiral. Chiral morphologies of calcite are electrodeposited in the presence of tartaric, malic, and aspartic acid. Calcite grows with left-handed spirals when deposited from l -tartaric acid but grows with right-handed spirals when deposited from l -malic acid or l -aspartic acid. A racemic mixture of d - and l -malic acid produces an achiral microstructure, instead of producing a racemic mixture of chiral microstructures.