Influence of divalent cations on the biofouling behaviors of alginate hydrogels

Alginate is one of the most favorable materials in many biomedical applications. The mechanical properties of alginate hydrogels can be easily tailored by adding different concentrations of divalent cations. In this work, we demonstrate that the method can also notably influence the biofouling behaviors of alginate hydrogels. A series of alginate hydrogels was prepared by tuning the concentrations of two types of divalent cation (Ca²⁺ or Ba²⁺). It was found that the biofouling behaviors of the hydrogels exhibited a 'U' curve tendency with the cation concentrations. Interestingly, we found that in optimal conditions ([Ca²⁺] = 0.9 mM or [Ba²⁺] = 0.54 mM), the resultant Ca_0.9- and Ba_0.54-alginate hydrogels were able to achieve negligible adhesion of the proteins and bacteria. Moreover, these two formulations were also able to prevent inflammatory responses at least 4 weeks after subcutaneous implantation in a mouse model. The findings in this work provide more insights into the design and development of appropriate alginate hydrogels for different applications.