Novel hydroxyapatite/tussah silk fibroin/chitosan bone-like nanocomposites

Abstract

The nanocomposite particles of hydroxyapatite–tussah silk fibroin (HA–TSF) and HA–chitosan (HA–CS) were developed by biomimetic synthesis using Ca(NO3)2 and Na3PO4 as the precursors of inorganic phase in the presence of TSF and CS. Both nanocomposite particles were carbonate-substituted HA with low crystallinity. TSF and CS induced preferential alignment of HA crystallites along the direction of c-axis, and the induction effect of TSF was more than of CS. HA–TSF and HA–CS nanocomposite particles were found to be needle-like in the shape with a typical size of 100–200 nm in length and about 20 nm in width, and 115–250 nm in length and about 25 nm in width, respectively, as the result of the preferential arrangement of HA crystallites along c-axis intensified by TSF and CS. Based on both nanocomposite particles, the bone-like nanocomposites of HA–TSF/CS and HA–CS/TSF with the same compositions were prepared by isostatic pressing using CS and TSF concentrated solutions as adhesive composition, respectively. However, the two bone-like nanocomposites exhibited significantly different mechanical properties. The compressive strength, compressive modulus, and bending strength of HA–TSF/CS composite were significantly higher than of HA–CS/TSF composite. The fracture mechanism of both composites was analyzed by SEM observation. The study result indicates that HA–TSF/CS nanocomposite is an ideal candidate for bone substitute materials.