Surface nanoscale patterning of bioactive glass to support cellular growth and differentiation

Bioactive glasses (BGs) have been widely used for bone tissue regeneration as they are able to bond directly with bone. Clinical applications of these materials are likely to be in particulate form. Nanoscale materials can mimic the surface properties of natural tissues, which have exhibited superior cytocompatible property and improved tissue regeneration. The objective of this study is to prepare bioactive glass particles with nanoscale or non-nanoscale surface features and investigate their microstructure, apatite-forming bioactivity and cellular response. The microstructure and micro-nanoscale surface morphology were controlled by adding a hydroxyl-carboxyl acid (citric acid) in the sol-gel process. Results shown that the addition of citric acid induced the formation of nanoscale surface structure and increased the specific surface area, pore volume and pore size of bioactive glass particles. The citric acid with low-concentration-derived sol-gel bioactive glasses (CBGs) resulted in an enhanced apatite-formation ability in simulated body fluids (SBF) compared to normal bioactive glasses. The attachment and proliferation of rat marrow mesenchymal stem cells (RMSCs) on CBGs (low concentration) were higher than those of normal BGs, demonstrating that the CBGs had the excellent cytocompatibility. RMSCs on CBGs (low concentration) expressed the higher alkaline phosphatase activity (ALP) than normal BGs and tissue culture plastic, revealing that CBGs can induced differentiation of RMSCs to the osteogenic lineage. Such improved physical and biological properties of CBGs (low concentration) should be useful in developing new bioactive glass materials for stem cell-based bone regeneration or biomimic tissue engineering scaffolds.