Surfactant-rescued gelation: Stabilizing P123-chitosan hydrogels in blood-isotonic aqueous solutions for controlled drug delivery.

The loss of gelation in Chitosan-Pluronic composite hydrogels under physiological saline conditions restricts their potential for drug delivery applications. To this effect, we present a dynamic and composite hydrogel system based on Pluronic P123 and chitosan, which restores gelation upon the addition of sodium dodecyl sulfate (SDS), even in the presence of NaCl at blood-isotonic concentrations. The entry of SDS induces electrostatic interactions and hydrophobic associations, enabling robust gel formation under physiological conditions. The gelation behavior can be desirably modified by varying chitosan concentration and temperature, allowing tunable mechanical properties suitable for drug delivery applications. Rheological analysis confirmed enhanced mechanical stability in saline environments, while FTIR spectroscopy elucidated molecular interactions within the hydrogel. Quinine sulfate release studies showed sustained drug release without burst effects. Kinetic modeling indicated a predominantly non-Fickian transport mechanism, governed by both diffusion and polymer relaxation. This surfactant-rescued gelation strategy stabilizes chitosan-based hydrogels in physiological conditions, making them promising candidates for controlled drug delivery.