Novel mesoporous silica-based antibiotic releasing scaffold for bone repair

Tissue engineering scaffolds with a micro- or nanoporous structure and able to deliver special drugs have already been confirmed to be effective in bone repair. In this paper, we first evaluated the biomineralization properties and drug release properties of a novel mesoporous silica-hydroxyapatite composite material (HMS-HA) which was used as drug vehicle and filler for polymer matrices. Biomineralization can offer a credible prediction of bioactivity for the synthetic bone regeneration materials. We found HMS-HA exhibited good apatite deposition properties after being soaked in simulated body fluid (SBF) for 7 days. Drug delivery from HMS-HA particle was in line with Fick's law, and the release process lasted 12 h after an initial burst release with 60% drug release. A novel tissue engineering scaffold with the function of controlled drug delivery was developed, which was based on HMS-HA particles, poly(lactide-co-glycolide) (PLGA) and microspheres sintering techniques. Mechanical testing on compression, degradation behavior, pH-compensation effect and drug delivery behavior of PLGA/HMS-HA microspheres sintered scaffolds were analyzed. Cell toxicity and cell proliferation on the scaffolds was also evaluated. The results indicated that the PLGA/HMS-HA scaffolds could effectively compensate the increased pH values caused by the acidic degradation product of PLGA. The compressive strength and modulus of PLGA/HMS-HA scaffolds were remarkably high compared to pure PLGA scaffold. Drug delivery testing of the PLGA/HMS-HA scaffolds indicated that PLGA slowed gentamycin sulfate (GS) release from HMS-HA particles, and the release lasted for nearly one month. Adding HMS-HA to PLGA scaffolds improved cytocompatibility. The scaffolds demonstrated low cytotoxicity, and supported mesenchymal stem cells growth more effectively than pure PLGA scaffolds. To summarize, the data supports the development of PLGA/HMS-HA scaffolds as potential degradable and drug delivery materials for bone replacement.