Degradation of Calcium Gels of Alginate and Periodate Oxidised Alginate

Abstract

The extracellular matrix (ECM) functions as a structural scaffold for cells and controls cellular function through cell-matrix interactions. These interactions are required by most cells in order to maintain viable and promote proliferation. Therefore, an appropriate synthetic extracellular matrix is necessary for tissue engineering applications. Hydrogels, either derived from synthetic or natural polymers, are an alternative. Alginate is a linear co-polymer formed by (1→4)-linked α-D-mannuronate (M) and its C-5 epimer β-L-guluronate (G). This natural polymer can be grafted with short bioactive peptide sequences by resorting to periodate oxidation and reductive amination, which can promote cell attachment. This work studied the effects of saline treatment on the mechanical properties and stability of calcium gels of stipe alginate and oxidised alginate. The results showed that Ca-alginate gels of chemically modified alginate are more prone to degradation than stipe alginate when subjected to saline treatments. This was viewed as a decreasing Young s modulus and storage modulus of the gels as a function of saline treatments. Additionally, the leaked material from the gels presented an initially low G-content and average G-block length, which then increased, indicating that the mixed-in partially oxidised alginate leaked out first. In sum, the use of periodate oxidation allowed to tailor the degradation rate of calcium alginate gels by varying the content of chemically modified alginate.