Drug delivery from hydroxyapatite-coated titanium surfaces using biodegradable particle carriers

The goal of this study was to develop a functional titanium (Ti) implant loaded with bioactive molecules using biodegradable polymeric particles as drug delivery carrier for dental applications. In this study, dexamethasone (DEX)- loaded poly(lactic-co-glycolic acid) (PLGA) particles were electrostatically immobilized on a Ti disc surface coated with hydroxyapatite (HA) nanocrystals using a low temperature high speed collision (LTHSC) method. Resorbable blasting media (RBM) Ti discs (S1), HA-Ti discs (S2), and HA-Ti discs treated with DEX-loaded PLGA particles (S3) were fabricated in this study as sample discs. To facilitate surface immobilization, PLGA particles were coated with polyethyleneimine (PEI) to produce a positive surface charge. This modification of PLGA particle surfaces, allowed DEX-loaded PLGA particles to be immobilized on negatively charged S2 disc surface. It was found that DEX-loaded PLGA particles were well dispersed and immobilized onto the S3 disc surfaces. Release profile studies of DEX from S3 discs in a 4-week immersion study indicated an initial burst release followed by sustained release. In vitro evaluation of bone marrow derived mesenchymal stem cells (BMSCs) cultured for 1 and 2 weeks on S3 discs showed greater BMSC differentiation than on S1 or S2 discs, demonstrating that this innovative delivery platform potently induced BMSC differentiation in vitro, and suggesting that it could be exploited for stem cell therapy purposes or to enhance in vivo osteogenesis. In addition, the results of the present study shows that various bioactive molecules that promote bone regeneration can be efficiently incorporated onto HA-Ti surfaces using biodegradable polymeric particles.