7475-00-5Relevant articles and documents
Ratiometric fluorescent sensor based on inhibition of resonance for detection of cadmium in aqueous solution and living cells
Xue, Lin,Li, Guoping,Liu, Qing,Wang, Huanhuan,Liu, Chun,Ding, Xunlei,He, Shenggui,Jiang, Hua
, p. 3680 - 3690 (2011)
Although cadmium has been recognized as a highly toxic heavy metal and poses many detrimental effects on human health, the Cd2+-uptake and nosogenesis mechanisms are still insufficiently understood, mainly because of the lack of facile analytical methods for monitoring changes in the environmental and intracellular Cd2+ concentrations with high spatial and temporal reliability. To this end, we present the design, synthesis, and photophysical properties of a cadmium sensor, DQCd1 based on the fluorophore 4-isobutoxy-6-(dimethylamino)-8-methoxyquinaldine (model compound 1). Preliminary investigations indicate that 1 could be protonated under neutral media and yield a resonance process over the quinoline fluorophore. Upon excitation at 405 nm, 1 shows a strong fluorescence emission at 554 nm with a quantum yield of 0.17. Similarly, DQCd1 bears properties comparable to its precursor. It exhibits fluorescence emission at 558 nm (Φf = 0.15) originating from the monocationic species under physiological conditions. Coordination with Cd2+ causes quenching of the emission at 558 nm and simultaneously yields a significant hypsochromic shift of the emission maximum to 495 nm (Φf = 0.11) due to inhibition of the resonance process. Thus, a single-excitation, dual-emission ratiometric measurement with a large blue shift in emission (Δλ = 63 nm) and remarkable changes in the ratio (F495 nm495/F558 nm) of the emission intensity (R/R 0 up to 15-fold) is established. Moreover, the sensor DQCd1 exhibits very high sensitivity for Cd2+ (Kd = 41 pM) and excellent selectivity response for Cd2+ over other heavy- and transitionmetal ions and Na+, K+, Mg2+, and Ca2+ at the millimolar level. Therefore, DQCd1 can act as a ratiometric fluorescent sensor for Cd2+ through inhibition of the resonance process. Confocal microscopy and cytotoxicity experiments indicate that DQCd1 is cellpermeable and noncytotoxic under our experimental conditions. It can indeed visualize the changes of intracellular Cd2+ in living cells using dual-emission ratiometry.
