Amino-Carrageenan@Polydopamine Microcomposites as Initiators for the Degradation of Hydrogel by near-Infrared Irradiation for Controlled Drug Release

A hydrogel immobilized with light-responsive amino group was developed by using amino-kappa carrageenan (amino-CG) and polydopamine (PDA). In the hybrid amino-CG@PDA microcomposite system, amino-CG was used to encapsulate PDA microspheres that act as a photothermal agent. Near infrared (NIR) irradiation is absorbed by the PDA to generate heat, releasing the amino-CG via gel-to-sol phase transition. By precisely controlling the transition temperature of amino-CG gel at 40 °C by adding a KCl hardening solution at the appropriate concentration, we successfully developed a composite hydrogel that dissolves at 40 °C when heated with NIR irradiation. The amino-CG@PDA was further composited into an aldehyde-introduced dextran hydrogel, which was reported to degrade by reaction with amino compounds. Utilizing the amino-CG release via NIR irradiation, we can successfully control the release of drug incorporated in the hydrogel, in which the NIR irradiation helps to diffuse amino-CG into the dextran hydrogel to initiate the hydrogel degradation by the reaction with aldehyde.