A New Gallium Crosslinked Alginate/Nanobioactive Glass Composite For Bone Tissue

V. MOURIÑO; P. NEWBY; J.P. CATTALINI; SILVIA LUCANGIOLI; A. R. BOCCACCINI

Jena

Simposio; Euro Biomat: European Symposium on Biomaterials and Related Areas; 2011

DGM

Recent studies have found that gallium ion (Ga3+), a drug approved for clinical used, inhibits S. aureus. Alginates (ALG) are able to form gels with multivalent metal ions, such as Ga3+, which induce cross-linking of their guluronic residues. In addition, nanoparticulate bioactive glasses (BG) can be also combined with biodegradable polymers to improve the mechanical and physical properties of the matrix increasing its versatility; in particular if an application in BTE is envisaged. The above considerations prompted us to develop a novel nano bioactive glass containing ALG cross-linked with Ga3+ films as a preliminary step for assessing the viability of using these composites in the elaboration of multifunctional 3D scaffolds for BTE with the added value of incorporating a drug delivery system to prevent possible bacterial colonisation of the biomaterial following implant surgery. Materials and Methods: Films were fabricated using a solvent casting following by immersion into a solution of gallium nitrate for crosslinking. Morphology features of the films were observed by SEM and EDX were used to confirmed the presence of Ga3+. The tensile strength at break of the films was measured using a dynamometer at a speed of 1 mm/min. The scaffolds were incubated in simulated body fluid (SBF) at 37°C for different times to evaluate bioactivity. The release of Ga3+ was quantified by atomic absorbtion. The antibacteriostatic properties were investigated by using S. aureus (ATCC 29213) through the antimicrobial disk susceptibility test. In vitro cell culture studies were conducted using osteoblast like human osteosarcoma cells line (MG-63). The measurement of cell viability on the films was carried out using the AlamarBlue assay kit. Results and Discussion: SEM observations showed films with uniform surface morphology in all cases. EDX analysis revealed that Ga3+ ions were successfully incorporated within the films. The tensile strengths at break of the films with BG were significantly higher than the films without BG. Biomineralization studies showed the deposition of hydroxyapatite on the surface of the films suggesting their bioactive nature. The fabricated films supported cell proliferation. In addition, the release of Ga3+) was controlled by crosslinking the ion with alginate. It was shown that Ga-crosslinked composites films possessed excellent physicochemical, biological and drug-release properties. These preliminary studies suggest that these composite films are thus promising candidates for bone tissue engineering applications and they could be applied to design 3D scaffolds with enhanced bioactivity.