期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 110, 期 23, 页码 9261-9266出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1222162110
关键词
biomineralization; calcium carbonate; free energy; algae; crustacean
资金
- US Department of Energy (USDOE) [DOE BES-FG02-00ER15112]
- National Science Foundation [NSF OCE-1061763]
- Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences of the USDOE [DE-AC02-05CH11231]
Calcified skeletons are produced within complex assemblages of proteins and polysaccharides whose roles in mineralization are not well understood. Here we quantify the kinetics of calcite nucleation onto a suite of high-purity polysaccharide (PS) substrates under controlled conditions. The energy barriers to nucleation are PS-specific by a systematic relationship to PS charge density and substrate structure that is rooted in minimization of the competing substrate-crystal and substrate-liquid interfacial energies. Chitosan presents a low-energy barrier to nucleation because its near-neutral charge favors formation of a substrate-crystal interface, thus reducing substrate interactions with water. Progressively higher barriers are measured for negatively charged alginates and heparin that favor contact with the solution over the formation of new substrate-crystal interfaces. The findings support a directing role for PS in biomineral formation and demonstrate that substrate-crystal interactions are one end-member in a larger continuum of competing forces that regulate heterogeneous crystal nucleation.
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