A biocompatible hydrogel as a template for oxidative decomposition reactions: a chemodosimetric analysis and imaging of hypochlorite.

The self-assembly properties of new biocompatible, thermoreversible fluorescent hydrogels, composed of amino acid residues, , l-phenylalanine (PyL-PheOx) and l-tyrosine (PyL-TyrOx), have been reported. Spectroscopic investigations indicate that PyL-PheOx forms π-stacked 'compact' aggregates, while 'loose' aggregates with stronger CT characteristics are observed for PyL-TyrOx. Both the compounds showed the presence of fibrous networks in the self-assembled state. Circular dichroism spectral studies indicate the formation of -helical and -helical structures for PyL-PheOx and PyL-TyrOx, respectively. A striking gel-to-sol transition, caused by oxidative decomposition, is explicitly noticed in the presence of hypochlorite. A mechanistic investigation reveals the oxidation of the acyl aroyl hydrazine core of the gelators in the presence of ClO. In addition to this, change in the fluorescence emission intensity of the hydrogel in the presence of ClO is utilized for the analysis of commercial bleach samples. Gel-coated paper strips are also developed for the on-site detection of ClO. Furthermore, the system is utilized for imaging hypochlorite in live mammalian cells.