A facile strategy for growing the comb-shaped poly (epsilon-caprolactone) brushes on the surface of nano-hydroxyapatite (n-HAP) by combination of atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP) would be presented. Firstly, ATRP was used to graft poly (2-hydroxyethyl methacrylate) (PHEMA) onto the n-HAP surface. Then, the hydroxyl groups introduced onto the n-HAP were used to initiate the ROP of epsilon-caprolactone for constructing comb-shaped polymer brushes on the surface of n-HAP. The surface modified n-HAP was characterized by Fourier transform infrared (FT-IR) spectra, C-13 solid-state cross-polarization magic-angle-spinning (C-13 CP/MAS), and thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM) measurements, respectively. The results demonstrated that the comb-shaped poly (epsilon-caprolactone) brushes had been grafted successfully, and the grafting ratio could be controlled well by adjusting the feed ratio of initiator and monomer. (C) 2010 Elsevier Inc. All rights reserved.