The effect of alginate addition on the structure and morphology of hydroxyapatite/gelatin nanocomposites

A series of hydroxyapatite/gelatin/alginate nanocomposites with different amount of alginate were synthesized by a co-precipitation method. With the increase of alginate amount, a cross-linked alginate/gelatin polymer network formed, which induced a gradual red shift of organic absorption peaks in FT-IR analysis. TEM images indicated that the development of HAP nanocrystals in an aqueous gelatin/alginate mixture was highly influenced by the alginate content. On increasing alginate content, the dimensions of the crystals increased and their morphology changed from needle-like to long fiber-like, and at high alginate content, the crystals tended to aggregate in separate clusters. The results of the electron diffraction strongly indicated alginate promoted the preferential alignment in c direction of HAP nanocrystals. SEM results showed that high amount of alginate led to regular shape and large size of HAP crystals after the composites were calcined for 4 h at 600 °C.