cg3001653_si_001.pdf (1.77 MB)
Solution–Air Interface Synthesis and Growth Mechanism of Tooth Enamel-like Hydroxyapatite/Chondroitin Sulfate Films
journal contribution
posted on 2012-07-03, 00:00 authored by Yifei Xu, Guobin Ma, Xiyan Wang, Mu WangHierarchically self-assembled hydroxyapatite (HAP) and
organic
composite resembling tooth enamel has potential biological and surgery
applications. Controlled fabrication remains a great challenge. In
this work, large-scale translucent hydroxyapatite (HAP) and chondroitin
sulfate (ChS) composite films are fabricated by a unique solution–air
interface method. The products excellently represent the characteristic
hierarchical “prism” structure of tooth enamel. We demonstrate
that the films are formed by evaporation-induced nucleation at the
interface and subsequent self-confined spherulitic growth. The supersaturation
at the interface increases upon solution evaporation, and the local
high supersaturation triggers preferred nucleation there. The spherulitic
growth is regulated by ChS and limited by the interfaces between the
spherulites as well as the solution and air. Consequently, HAP/ChS
films with the hierarchically self-assembled prism structure are produced.
We emphasize that the mechanism can excellently explain the unique
prism structure formation in tooth enamel and in self-assembled nanorod
arrays. The findings provide insight into the fundamentals of hierarchical
assembly in nature (e.g., assembly of tooth enamel). Moreover, the
approach could be expanded to design and grow other sophisticated
functional structures.