Reaction-Based Fluorescent Probes for Detection of Zinc

Technology

A zinc-reactive protecting group is added to the sensor scaffold, thereby creating a non-fluorescent sensor precursor. Upon binding of zinc, the ester is hydrolyzed via a zinc-mediated process, resulting in a restoration of fluorescence.  This modification increases the dynamic range, reduces the pH-sensitivity of the metal-free state, and improves the efficiency with which the probes can be targeted to intracellular locales by reducing endo/lysosomal entrapment. These probes also offer improved solubility and can be applied to cells at lower probe concentrations than are typical. Furthermore, unlike most reaction-based probes, the zinc-induced fluorescence can be partially reversed in the presence of a chelator.  

Problem Addressed

Zinc is an essential nutrient. Chelatable or “mobile” forms of zinc can act as signaling agents, the actions of which have been directly implicated in numerous physiological and pathological processes, such as neurotransmission, neurogenesis, cancer, diabetes, and acute inflammation.  Understanding the role of mobile zinc in biology requires tools that can be used to visualize and track the changes of mobile zinc levels in diverse cellular and subcellular environments. Unfortunately, most commercially available small-molecule probes for mobile zinc have a narrow dynamic range, adventitious localization, and/or a pH-sensitivity, which limits their utility.  

Advantages

• A significantly improved dynamic range and pH profile
• Resistance to water and esterase-mediated hydrolysis both in vitro and in vivo
• The ability to target subcellular organelles such as mitochondria  

Publications

"Reaction-Based Fluorescent Sensor for Investigating Mobile Zn2+ in Mitochondria of Healthy Versus Cancerous Prostate Cells." Proceedings of the National Academy of Sciences 111, no. 16 (2014): 5990-5995.

"Peptide Targeting of Fluorescein-Based Sensors to Discrete Intracellular Locales." Chemical Science 5, no. 9 (2014): 3449-3454.

"New Sensor Tracks Zinc in Cells." MIT News, December 9, 2013.