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Amorphous Calcium Carbonate Stabilized by a Flexible Biomimetic Polymer Inspired by Marine Mussels
journal contribution
posted on 2013-05-01, 00:00 authored by Sha-Sha Wang, An-Wu XuOrganisms make use of amorphous materials
as a certain precursor
to form insoluble complex biominerals in the presence of various organic
matrices. In this article, we demonstrate that amorphous calcium carbonate
(ACC) nanoparticles can be highly stabilized by a polymerized dopamine
(DA), a biomimetic molecule inspired by adhesive proteins in mussels.
The cross-linking polydopamine (PDA, a mussel mimicking polymer) flexible
chains are adhesively associated with the ACC particles to form ACC@PDA
core–shell spheres. We are able to modulate the thickness of
PDA shells in the range of a few to several tens of nanometers by
adjusting the additive DA amount. The thickness of this mussel mimicking
PDA shell significantly influences the stability of ACC nanoparticles;
the thicker the PDA shell is, the more stable the ACC core is. The
obtained ACC–PDA hybrid particles have high stability, partly
because the complexing interaction of Ca2+ ions with PDA
and encapsulating PDA networks inhibit ACC dissolution and retard
subsequent Ostwald ripening, and partly because the PDA coating builds
isolated confinement spaces for ACC that prevents contacting and merging
of ACC particles which further restrains possible solid-phase transformation.
Notably, the protecting effects of PDA endow the obtained ACC–PDA
composite powder with enough stability to exist for at least one year
in the solid state. Our resulting hybrid ACC–PDA nanoparticles
with tunable size and high stability could serve as a model system
for multistep biomineralization, limited space crystallization, and
potential biomedical applications as well.