Electrophoretic deposition of dexamethasone-loaded mesoporous silica nanoparticles onto poly (L-lactic acid)/poly (?-caprolactone)composite scaffold for bone tissue engineering.

The incorporation of microcarriers as drug delivery vehicles into polymeric scaffold for bone regeneration has aroused increasing interest. In this study, the aminated mesoporous silica nanoparticles (MSNs-NH2)were prepared and used as microcarriers for dexamethasone (DEX)loading. Poly(L-lactic acid)/poly(?-caprolactone)(PLLA/PCL)nanofibrous scaffold was fabricated via thermally induced phase separation (TIPS)and served as template, onto which the drug-loaded MSNs-NH2 nanoparticles were deposited by electrophoretic deposition (EPD). The physicochemical and release properties of the prepared scaffolds (DEX@MSNs-NH2/PLLA/PCL)were examined, and their osteogenic activities were also evaluated through in vitro and in vivo studies. The release of DEX from the scaffolds revealed an initial rapid release followed by a slower and sustained one. The in vitro results indicated that the DEX@MSNs-NH2/PLLA/PCL scaffold exhibited good biocompatibility to rat bone marrow-derived mesenchymal stem cells (BMSCs). Also, BMSCs cultured on the DEX@MSNs-NH2/PLLA/PCL scaffold exhibited a higher degree of osteogenic differentiation than those cultured on PLLA/PCL and MSNs-NH2/PLLA/PCL scaffolds, in terms of alkaline phosphatase (ALP)activity, mineralized matrix formation, and osteocalcin (OCN)expression. Furthermore, the in vivo results in a calvarial defect model of Sprague-Dawley (SD)rats demonstrated that the DEX@MSNs-NH2/PLLA/PCL scaffold could significantly promote calvarial defect healing compared with the PLLA/PCL scaffold. Thus, the EPD technique provides a convenient way to incorporate osteogenic agents-containing microcarriers to polymer scaffold, and thus, prepared composite scaffold could be a potential candidate for bone tissue engineering application due to its capacity for delivery of osteogenic agents.