Chitosan and hydroxyapatite composite cross-linked by dopamine has improved anisotropic hydroxyapatite growth and wet mechanical properties

Abstract

Three of the major impediments to using hydroxyapatite (HAp)-collagen composites for hard tissue repair are the difficulties in anisotropic growth of HAp, in functional collagen production, and in their cross-linking. To solve these problems, we fabricated HAp-based composites for hard tissue repair by using chitosan as a collagen matrix substitute, and dopamine as a replacement for aldehyde-based cross-linkers. In the presence of chitosan and dopamine, the HAp particles grew anisotropically in a needle shape with an aspect ratio of similar to 4.4. The needle-shaped HAp particles were dispersed well in the chitosan matrix, and dopamine-mediated cross-linking enhanced the stiffness and reduced swelling in the presence of water. The composite is too weak for use in hard tissue repair, but could be used for curing dentin sensitivity by blocking and remineralization on dentinal tubules, and in drug-delivery applications.