Synthesis and characterization of elastic and macroporous chitosan–gelatin cryogels for tissue engineering

Elastic chitosan–gelatin cryogels of varying concentration of polymer precursors have been synthesized using glutaraldehyde as a crosslinking agent. The optimum co-polymer ratio of chitosan to gelatin was found to be 1:4 at the temperature of −12 °C for synthesis of chitosan–gelatin hybrid cryogels. chitosan–gelatin cryogels synthesized with low viscosity chitosan were morphologically better than those formed with medium and high viscosity chitosan. Pore diameters of chitosan–gelatin cryogels as measured by scanning electron microscopy (SEM) was in the range of 30–100 μm. While mercury porosimetry analysis revealed the majority of pores of the scaffold lying in the range of 30–50 μm. Porosity of chitosan–gelatin cryogels was found to be greater than 90% using Archimedes’s principle. Unconfined compression tests showed significant elasticity of chitosan–gelatin cryogels and maintained their physical integrity even after compressing them up to 80% of their original length. The elastic modulus varied in the range of 36–39 kPa. Cyclic deformation analysis performed by compression of chitosan–gelatin cryogels with varying strains (10, 20 and 40%) showed no cracking or any significant deformation. The degradation of chitosan–gelatin cryogels was found up to 13.58 ± 1.52% at 37 °C within 8 weeks of incubation under sterile conditions and the cryogels swelled up to 90% of their capacity within two min. Efficient cell adherence, proliferation and extracellular matrix (ECM) secretion was observed by growing fibroblast (Cos-7) cell line on chitosan–gelatin hybrid cryogels which indicate potential of the material for tissue engineering applications.