Chemically triggered soft material macroscopic degradation and fluorescence detection using self-propagating thiol-initiated cascades

In this article, we present a new approach for thiol detection through chemically triggered polymeric macroscopic degradation using self-propagating cascades, coupled with photoluminescence. Initially, a new heterocyclic chromophore was synthesized through cyclization of a single conjugate acceptor, showing cyclization induced emission as the source of the luminescence in an aqueous buffer. The reaction between the conjugate acceptor and β-mercaptoethanol led to 160-fold fluorescence enhancement in the aqueous buffer. By utilizing these physiochemical reactions, a poly(ethylene glycol) hydrogel, coupled with 2-hydroxyethyl disulfide to form self-propagating cascades, can be triggered by a thiol to undergo polymeric degradation. In addition to the macroscopic morphological changes, the degradation can be monitored by fluorometric signal amplification in the presence of the thiol as a detection event. Also, the biomolecule glutathione (GSH) was detected and quantitated using the soft material based self-propagating thiol-initiated cascades. Herein, a strategy of thiol-triggered hydrogel degradation and fluorescence detection of GSH through signal amplification offer a new analytical method using stimuli-responsive “intelligent” materials.