The silk sericin (SS)/hydroxyapatite (HAP) composite was synthesized via a chemical co-precipitation method. The effect of mineralization time on the formation of composite, including growth of crystal, aggregation and assembly of nanoparticles, was investigated using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The results revealed that the mineralization time could influence the size, morphology and assembly of SS/HAP composite, i.e., long mineralization time leading to the large composite particles with high hydroxyapatite crystallinity. A more interesting thing was that the rod-like composite particles with 300～500 nm in length and 50～80 nm in diameter were assembled along the c-axis by the small nanoparticles with a size of about 20 nm, which is very similar to the assembly of natural enamel. The formation mechanism of enamel-like microstructure of SS/HAP composite was proposed.

Key words: hydroxyapatite, silk sericin, molecular assembly, enamel-like