Rod-shaped hydroxyapatite with mesoporous structure as drug carriers for proteins

Rod-shaped hydroxyapatite (HAp) with mesoporous structure was synthesized by a hydrothermal method using Pluronic block co-polymer F127 as the template. The rod-shaped HAp was then tested as protein drug carriers by investigating their protein adsorption/release properties. Bovine serum albumin (BSA) and lysozyme (LSZ) were used as the model drugs. Various instrumental methods were used to characterize the structure, morphology, texture and protein drug adsorption/release properties of the samples. The amounts of BSA or LSZ adsorbed onto the rod-shaped HAp and their release profiles were evaluated in a simulated body fluid (SBF). The synthesized rod-shaped HAp had irregular mesostructures with lengths of 75-125 nm and diameters of about 25 nm. The rod-shaped HAp exhibited a higher loading capacity for BSA than for LSZ in the SBF. This adsorption behavior can be explained by the morphology of the rod-shaped HAp, which grew along the c-axis, leading to an a(b)-plane area that is larger than the c-plane area. Consequently, the number of positive charges on the surface of the rod-shaped HAp increased relative to the number of negative charges. The BSA release rate in SBF was slower than that of LSZ which is a result of the HAp surface properties.