Abstract
| - This study introduces new concepts in the design, synthesis, and in vitro and in vivo characterization,manipulation, and imaging of organic chelates whose association with metal ions is rapidly and reversiblycontrolled by using light. Di- and tricarboxylic group bearing photochromes, nitrobenzospiropyran(nitroBIPS), undergo rapid and reversible, optically driven transitions between their spiro (SP) andfluorescent merocyanine (MC) states. The MC state of nitroBIPS-8-DA binds tightly to various metalions resulting in specific shifts in absorption and fluorescence, and the dissociation constant for itsGadolinium complex in water is measured at ∼5 μM. The metal-bound MC state is converted to theweaker-binding SP state with use of 543 nm light, while the SP to MC transition is complete with useof 365 or 720 nm (2-photon) light within several microseconds. Fluorescence imaging of the MC stateof nitroBIPS-8-TriA was used to quantify the rate and efficiency of optical switching and to provide areal-time readout of the state of the optically switchable chelate within living cells.
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