Biomimetic Growth of Hydroxyapatite on SiO₂ Microspheres to Improve Its Biocompatibility and Gentamicin Loading Capacity

The interest in multifunctional biomaterials to be implanted are also able to release drugs that reduce pain and inflammation or prevent a possible infection has increased. Bioactive materials such as silica (SiO₂) containing surface silanol groups contribute to the nucleation and growth of hydroxyapatite (HAp) in a physiological environment. Regarding biocompatibility, the spherical shape of particles is the desirable one, since it does not cause mechanical damage to the cell membrane. In this work, the synthesis of SiO₂ microspheres was performed by the modified Stöber method and they were used for the biomimetic growth of HAp on their surface. The effect of the type of surfactant (sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB), and polyethylene glycol (PEG)), and heat treatment on the morphology and size of SiO₂ particles was investigated. Monodisperse, spherical-shaped SiO₂ microparticles with an average particle size of 179 nm, were obtained when using PEG (SiO₂-PEG). The biomimetic growth of HAp was performed on this sample to improve its biocompatibility and drug-loading capacity using gentamicin as a model drug. Biomimetic growth of HAp was confirmed by FTIR-ATR, SEM-EDX and TEM techniques. SiO₂-PEG/HAp sample had a better biocompatibility in vitro and gentamicin loading capacity than SiO₂-PEG sample.