| Summary: | 碩士 === 國立陽明大學 === 口腔生物研究所 === 105 === Titanium-24 wt% Niobium-4 wt% Zirconium-8 wt% Tin (Ti-24 wt% Nb-4 wt% Zr-8 wt% Sn, Ti2448) is a novel titanium alloy with high strength, high corrosion resistance, and good biocompatibility that makes it ideally suited for use as an implant material. Furthermore, its elastic modulus (42 GPa) is close to that of natural bone (< 40 GPa), which decreases the risk of stress shielding. Unfortunately, the bioinert nature of Ti2448 alloy means that surface modification is required to improve surface bioactivity and osteogenic response.
In this study, we employed sandblasting, acid etching and alkaline treatment to produce a roughened Ti2448 alloy surface with a submicron- and nano-scale porosity which was shown to promote the osteogenesis of bone cells. Non-cytotoxic gelatin nanoparticles containing vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), and bone morphogenetic protein-2 (BMP-2) were then sequentially immobilized on the surface-modified Ti2448 alloy using the natural crosslinker genipin. These gelatin nanoparticles were used as carriers to enhance mesenchymal stem cell migration and regulate osteoblast differentiation and bone formation due to the presence of angiogenesis stimulators VEGF and FGF-2, and to play an important role in skeletal growth and bone formation due to the presence of osteogenesis stimulator BMP-2.
To summarize, in this study, we used genipin to immobilize gelatin nanoparticles that contained VEGF + FGF-2 (in the outer layer) and BMP-2 (in the inner layer) on roughened Ti2448 alloy in order to produce a non-toxic multilayered structure. The structure of Ti2448 alloy was designed with both inner and outer layers to ensure the sequential release of osteogenesis-inducing growth factors. As for cell responses, the BMP-2-only layer could enhance the cell adhesion and mineralization; the VEGF, FGF-2, and BMP-2 multilayer (outer: VEGF + FGF-2; inner: BMP-2) could enhance the cell adhesion of human bone marrow mesenchymal stem cells. This novel approach to the immobilization of VEGF, FGF-2, and BMP-2-containing gelatin nanoparticles on roughened Ti2448 alloy surface has potential utility in orthopedic implant applications.
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