Study on the Fabrication, Optimization of Processing Parameters and Characterization of Collagen Based Vascularized Scaffolds for Biomedical Application

Abstract

Tissue engineering aims to produce biological substitutes which may overcome the limitations of conventional clinical treatments for damaged tissues or organs. Bone tissue engineering is aimed at repairing diseased or fractured bone, which cannot be replaced naturally. Skeletal tissue is a highly organized structure comprising mainly type I collagen, nanometer sized carbonate-substituted hydroxyapatite crystals, water and various other non-collagenous proteins. In this study, naturally derived collagen from rabbit skin and chemically synthesized hydroxyapatite, and chitosan were used for fabrication of highly porous hydroxyapatite-collagen-chitosan scaffolds through thermally induced phase separation technique and cross-linked with both chemical (GTA&EDAC/NHS) and physical (DHT treatment & radiation) cross-linkers. Morphological properties of the scaffolds were characterized by determination of its porosity, density, swelling ratio, biodegradability, compressive strength and chemical interaction within the composite etc. The porosity and density of the scaffolds were measured by liquid displacement method; the chemical interaction was analyzed by Fourier transform infrared spectroscopy (FTIR) analysis. The resulted data showed that the selected optimized scaffold possessed three dimensional interconnected homogenous porous structures with a porosity of >91% and the density were 0.13 to 0.18 g/cm3. The rate of swelling ratio of the scaffolds were 80 to 120%. The in-vitro biodegradability rate (after 28 days) of the fabricated scaffolds were varied from 38 to 42%. The mechanical strength of the scaffolds were ranged between 0.03 to 0.88 Nmm-2. FTIR data confirmed that there had an intermolecular interactions among the polymers and mineral content within the composites and with different types of cross-linkers. Biological properties of scaffolds are characterized by determination of its biocompatibility and cytotoxicity. Scaffolds have shown very inferior blood clotting propensity (clot weight 2.1 to 10.5 mg), slight rate of hemolysis (0.22 to 0.62%) which is acceptable for medical devices. The cytotoxicity test indicated that the fabricated scaffolds have no cytotoxic property (100% live count of nauplii at low scaffold inducted concentration) against brine shrimp cells. Above results suggest that, these promising hydroxyapatite-collagen-chitosan scaffolds are useful candidates for bone tissue engineering applications.