Hydrogen sulfide detection induced burst release of model drug from polymeric micelles

In this study, a poly(ester-amide)-based amphiphilic polymer (named P1) is prepared for the burst release of a model drug, rhodamine, from polymeric micelles, triggered by hydrogen sulfide (H2S) detection. P1 was synthesized by the Passerini multicomponent polymerization of a hydrophobic H2S-specific unit (M1) with 6-isocyanohexanoic acid, and hydrophilic polyethylene glycol (PEG) dicarboxylic acid. When P1 self-assembles in water, it generates polymeric micelles consisting of a hydrophilic PEG shell and a hydrophobic core derived from M1 with 6-isocyanohexanoic acid. P1 micelles exhibited selective colorimetric (colorless to yellow) and fluorometric (non-emissive to blue emission) H2S detection in water. The limit of detection was as low as 0.09 mM. Upon the exposure of H2S to a P1 micelle solution encapsulating the hydrophobic model drug, rhodamine, H2S detection induced a sequential and self-destructive elimination process of the polymer backbone, resulting in the swelling of the micelles and the abrupt release of rhodamine.