Design And Synthesis Of Novel Fluorescent Intracellular Ca～(2+) Probes

Calcium serves as an intracellular second messenger plays a very important role in biological systems,including almost all of the physiological and biochemical processes,such as the exocytosis, pinocytosis, the release of neurotransimitters, the synthesis of DNA, cell division and even apoptosis etc. Consequently, the measurement of the concentration and spatio-temporal distribution of intracellular free Ca²⁺ has been an important area of investigation in chemical, biological and clinic medical research and also an important hot research project in modern analytical chemistry.The method of fluorescent probes based on the invention of the first generation of fluorescent Ca²⁺ indicators ( also probes) ,developed by Tsien.R.Y in 1982 , has been a breakthrough for the development of measurement of intracellular free Ca²⁺, because of its sensitive and selective response to cell Ca²⁺ in physiological condition and the low even no damage and interference to cell. And the second and the third generation of the fluorescent Ca²⁺ probes were also synthesized later by Tsien. At present, most measurements of intracellular free Ca²⁺ are performed using fluorescent Ca²⁺ probes such as Quin-2, Indo-1, Fura-2 and Fluo-3. The important role of the intracellular Ca²⁺ has been studied detailedly and systemically and the mechanism of Ca²⁺ serves as the second messenger has been discovered and explored preliminarily with the fluorescent probes, which do a great contribution to further understanding of life event.But almost all of the fluorescent probes have some intrinsic and insurmountable drawbacks in that the excitation bands for probes Quin-2, Indo-1 and Fura-2 , occur at UV wavelength(340 360nm), where autofluorescence from cells is high and radiation-damage of cellular structures is serious, and for probe Fluo-3, a visible light-excitable Ca²⁺ probe, overcomes the limitation of Quin-2, Indo-1 and Fura-2 but no longer show any spectral shifts upon Ca²⁺ binding and thus ratiometric measurements are impossible. Particularly all of the fluorescent probes mentioned above are difficult to target precisely to specific intracellular locations and Important Ca²⁺ signals in the cytosol and organelles are hard to measure.In view of all the above discussed technological shortcomings, it is apparent that the field has urgently awaited the novel and high whole quality fluorescent Ca²⁺ probes.