GEMOSOL biomaterial technology for bone substitutes

A hydroxyapatite-gelatin nanocomposite system (HAP-GEL) was previously developed to resemble the composition and ultrastructure of natural bone for the application of tissue engineering (Ko et al., 2006). Objectives: The purpose of the present study was to develop gelatin modified sol gel technology (GEMOSOL) to improve the strength, formability and cytocompatibility of HAP-GEL. The GEMOSOL biomaterial consists of the following major components: HAP-GEL in the form of colloids, silica matrices of aminosilane (aminosilica), and trace amounts of TiO2. It was hypothesized that aminosilica binds strongly to both hydroxyapatite and gelatin through covalent and ionic interactions. Methods: Both nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) were utilized to test this hypothesis. Osteoblasts and tooth stem cells were cultivated on the surface of GEMOSOL-derived biomaterials to investigate its biocompatibility. Results: Solid state NMR revealed strong interactions that happen between the hydroxyl group of hydroxylproline and amine group of aminosilica. There was a hydrogen bond between carbonyl group of gelatin and amine in aminosilica. FTIR also confirmed the shift of these chemical bonds. Increased compressive strength in GEMOSOL biomaterials echoed such chemical interactions. The material solidified five times faster than HAP-GEL, and was resistant to erosion in aqueous solution after setting. As a result, various porous scaffolds, ranging from 300 µm to 1000 µm pore sizes, were created using the salt-leaching method. Cell culture showed excellent proliferation, differentiation, and good penetration depth into the scaffolds. Adding trace amount of TiO2 seemed to enhance cell adhesion and proliferation. Conclusion: GEMOSOL technology appears to surpass HAP-GEL in mechanical properties and forming ability for scaffolding, and is applicable for tissue engineering. In vivo study for bone regeneration in a rat model is underway (Supported, in part, by NIH/NIDCR K08DE018695, NC Biotech Grant#2008-MRG-1108, UNC Research Council, and American Association of Orthodontists Foundation.)