Evaluating the effect of pH on mechanical strength and cell compatibility of nanostructured collagen hydrogel by the plastic compression method

Objective(s): One of the main constraints of collagen hydrogel scaffolds for using in tissue engineering is mechanical weakness. Plastic compression (PC) is a physical method to overcome the mechanical limitation of collagen hydrogel. Materials and Methods: In this study, the effects of pH on mechanical and biological properties of PC hydrogels were investigated. Collagen hydrogels were fabricated at neutral (pH=7.4) and alkaline pH (pH=8.5), and then underwent plastic compression to prepare final hydrogels. The stability, mechanical properties, morphology and cell compatibility of hydrogels were investigated. Results: The results illustrated that increasing in polymerization pH was associated with improvement in both tensile strength and elastic modulus of hydrogels. Furthermore, cell viability assay confirmed cell survival in both hydrogels prepared at alkaline and neutral pH. Conclusion: The results suggest that a slightly basic pH during hydrogel production is an appropriate approach to construct PC collagen hydrogels with an enhanced stability and mechanical properties as well as better handling before PC process.