Gamma-Poly(glutamic acid)/Chitosan Composite Scaffolds for Tissue Engineering Applications

The development of tissue engineering provides a novel approach to restore bodily functions by seeding cells onto various scaffolds. Although chitosan is a non-toxic biomaterial, its cytocompatibility still needs to be improved. In this study, gamma-poly(glutamic acid) (γ-PGA) was blended with chitosan to prepare both dense and porous γ-PGA/chitosan composite scaffolds using the freeze-gelation method. This method saves time and energy, and there is less residual solvent. SEM micrographs demonstrated that an interconnected porous structure with a pore size of 30-100 micrometer was present in the scaffolds. The hydrophilicity of the scaffolds was significantly improved by γ-PGA. Further, the tensile strength of the porous γ-PGA-modified chitosan scaffolds was about 50% higher than that of the unmodified chitosan scaffolds. The number of osteosarcoma cells cultured on the γ-PGA-modified scaffolds was about double that on the unmodified chitosan scaffolds on day 7. Thus, the γ-PGA/chitosan composite scaffolds, due to their better hydrophilicity, cytocompatibility, and mechanical strength, are very promising biomaterials for tissue engineering applications. We further demonstrated the use of glutamic acid to enhance the tensile strength of chitosan-based composite porous scaffolds. The tensile strength of the chitosan/collagen composite scaffolds was increased by more than 2 times with the addition of glutamic acids as cross-linking bridges. We found that the hepatocytes attached and proliferated well on these composite scaffolds, demonstrating that the glutamic acid modified-chitosan composite scaffolds are also potential tissue engineering biomaterials.