Comprehensive Swelling Analysis of Alginate Hydrogel

Abstract Utilizing a combination of sodium tripolyphosphate (TPP) and sodium hexametaphosphate (HMP) as composite cross-linking agents, alginate hydrogels were prepared through ionic cross-linking. An analysis and discussion were conducted on the influence of crosslinking agent mass ratio, pH, and ionic strength on the swelling properties of alginate hydrogels. The findings reveal that the swelling degree of microspheres prepared with the composite crosslinking agent is reduced by 75.1% and 26.8% compared to using TPP or HMP separately, indicating a significantly enhanced cross-linking efficiency. When the mass ratio of TPP to HMP is set at 4:5 and the cross-linking agent pH is 6, the hydrogels demonstrated the utmost crosslinking and the most compact structure. In a pH 2.0 buffered solution, the swelling degree can reach 500%, and the gel remains intact without any breakage. The hydrogels exhibit notable sensitivity to both ionic strength and pH, displaying increased swelling particularly in acidic conditions.