Controlled hydrothermal synthesis of strontium-substituted hydroxyapatite nanorods and their application as a drug carrier for proteins

Abstract

Without the addition of any organic additives, both undoped hydroxyapatite (HAp) and different strontium (Sr)-substituted hydroxyapatite (SrHAp) samples with amounts from 1 to 20 mol.% were synthesized via hydrothermal route. The crystal texture, chemical functional group and microstructure were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and inductively coupled plasma (ICP), respectively. And the protein adsorption and release properties of bovine serum albumin (BSA) and lysozyme (LYS) were investigated on the samples to search for a well protein drug delivery vehicle. The results revealed that the pure HAp consisted of uniform nanobelts and all SrHAp samples had a rod-like morphology. The lattice parameters of SrHAp were larger than HAp, while they had similar crystal structure. The protein adsorption and release tests indicated that the incorporation of Sr into HAp lattice could increase the amounts of BSA and LYS adsorption. The BSA adsorption capacity of 1SrHAp was found to be 55.52 mg/g, which was about 14.64% higher than that of HAp. The 15SrHAp possessed the highest LYS loading amount of 90.54 mg/g, which was about three times that of HAp. And SrHAp exhibited sustained protein release capability.