Protect to Detect: A Golgi Apparatus Targeted Probe to Image Mobile Zinc Through the Use of a Lipophilic Cell-Labile Protecting Group Strategy

The Golgi apparatus requires zinc for its normal function, but the role it plays in these processes at the sub-cellular level is not well-understood due to the lack of appropriate tools to image it. Herein, a small molecule Golgi apparatus targeted probe was developed to image mobile Zn2+. A trityl group was used to protect a Golgi apparatus targeting cysteine residue to increase membrane permeability, which was then removed in cellulo within 24 hours, revealing the free cysteine targeting motif to anchor the probe to the Golgi apparatus. The probe shows good photophysical properties, good selectivity and Zn2+ response over a wide range of pH as well as low cellular toxicity. The probe was shown to be capable of targeting the Golgi apparatus and responding to Zn2+ in a number of different cell lines and was also applied to monitor the change of concentration of mobile Zn2+ in the Golgi apparatus in response to oxidative stress.