Temperature Affects the Hydroxyapatite Crystal Arrangement on Silk Fibroin Surfaces

A hydroxyapatite (HAP)/silk fibroin (SF) bone-like biomaterial was fabricated through a coprecipitation process using stepped temperatures. We evaluated the effect of increasing temperatures on hydroxyapatite crystal arrangement on a silk fibroin surface. We found that the HAP crystal particles self-assembled on the silk fibroin surface. Further we found that with rising temperature the HAP crystal c-axis became progressively more parallel to the long axis of the silk fibroin. This deposition pattern is similar to that seen with HAP and collagen assembly in normal bone. Based on the XRD, SEM, and TEM results, we conclude that higher temperatures promote crystal nucleation resulting in an increase in both HAP crystal size and HAP/SF particle size. These data support the use of HAP/SF bone-like biomaterials for bone replacement and regeneration.