Modulation of properties of self-healing cross-linker free gelatin alginate hydrogels using Hofmeister salts
The insights into the physical interactions within cross-linker-free hydrogels can unlock a new horizon on the modulation of their properties. The impact of interactions between Hofmeister salts and polymers on these hydrogels is unknown. This article considers the effect of four different salts and their mixtures on the design of cross-linker-free self-healing gelatin-alginate hydrogels. The impact of these salts on drug release, swelling, degradation and rheological properties is represented using a 3-D plot to identify optimum samples. It is concluded from the kinectic studies that kosmotropes show better release and swelling when compared to chaotropes. The hydrogels prepared with kosmotropes also show faster degradation which can be overcome using a kosmotrope and chaotrope mixture. The interactions between polymers and the salts are identified using dynamic light scattering and H-bond interactions (FTIR/ATR studies) and then corroborated with drug release, swelling, degradation and rheological analyses. Finally, the self-healing behaviour of hydrogels is studied, and structure recovery after its destruction is calculated. Another 3-D plot is generated considering the release kinetics, gel strength, and recovery percentage (three important factors for self-healing hydrogels) and optimum samples are identified. It is concluded that chaotropes show better self-healing behaviour (in terms of structure recovery). However, when gel strength, release kinetics and self-healing are considered, kosmotropes are favourable. It is also concluded that electrostatic forces from salts hinder the H-bonds formation.