Masked Amino Trimethyl Lock (H N-TML) Systems: New Molecular Entities for the Development of Turn-On Fluorophores and Their Application in Hydrogen Sulfide (H S) Imaging in Human Cells.

Masked trimethyl lock (TML) systems as molecular moieties enabling the bioresponsive release of compounds or dyes in a controlled temporal and spatial manner have been widely applied for the development of drug conjugates, prodrugs or molecular imaging tools. Herein, we report the development of a novel amino trimethyl lock (H N-TML) system as an auto-immolative molecular entity for the release of fluorophores. We designed Cou-TML-N and MURh-TML-N , two azide-masked turn-on fluorophores. The latter was demonstrated to selectively release fluorescent MURh in the presence of physiological concentrations of the redox-signaling molecule H S in vitro and was successfully applied to image H S in human cells.