Design, Synthesis Of New ClO~-/pH/Thiol Probe And Its Application Based On Xanthene Dye

Fluorescence imaging has been widely used because of its easy operation and not need complex material preparation process. Fluorescence imaging was made by fluorescent dye connected with specific target, so, it can use to detect of some certain small biological molecules. Organic small molecule fluorescent dyes own excellent performance and can be synthesized easy, therefore, it has been widely used in the detection of ions, enzyme analysis, cell imaging, various functional materials and so on. In this paper, we designed and synthesized three fluorescent probes (ClO-/pH/Thiol), and all were used xanthene dyes as precursor.Firstly, a new hypochlorite ion probe was designed and synthesized, which was used the xanthene dye as precursor. The dye was synthesized by the reaction between 2-(4-(diethylamino)-2-hydroxybenzoyl) benzoic acid and 4-hydroxy carbazole, moreover, the CRh dyes retained the characteristic of "on-off" ring of the classic rhodamine. Furthermore, the dye also has good stability in a wide range of pH. And then, we designed and synthesized a novel hypochlorite ion probe CRh-ClO on the basis of the dye CRh2, before treatment with ClO-, the probe CRh-ClO was no fluorescence, but after added in ClO-, the probe CRh-ClO show intense fluorescence enhancement. In addition, the probe CRh-ClO has some advantage, such as high selectivity and detection limit and response quickly. In the end, we further do cell imaging experiment with only added to probe CRh-CIO, the results show that the probe CRh-CIO can be used for the detection of intracellular hypochlorite ions.Secondly, we designed and synthesized a kind of xanthene fluorescent dyes which owned long emission wavelength and can be monitored by hydroxyl. These dyes have the common parent structure, but, they have different substituent, which were-H/ -OCH3/-OH. With the increasing of electron donating capacity, the fluorescence intensity of the dye also increased. Moreover, the dye FR-OH has very strong fluorescence, the fluorescence quantum yield was 0.57. Furthermore, the dye FR-OH also has good stability and cell membrane permeability. And then, We design a pH probe based on the dye FR-OH, the fluorescence was weakly in acidic conditions, but, with the increase of pH value, The fluorescence intensity was also greatly enhanced, which showing good enhanced response to pH value.Thirdly, We have designed and synthesized probe FR-thiol based on a protection/deprotection approach as a new turn-on fluorescent probe. The probe FR-thiol was designed by the reaction between 2,4-dinitroben-zenesulfonate with hydroxyl group. The probe FR-thiol was no fluorescent before addition to thiol, but, after treatment with thiol, probe FR-thiol showed strong fluorescence. In addition, the probe FR-thiol also has good selectivity, high detection limit and fast response time. Meanwhile, the cellular imaging experiments show that, the probe FR-thiol can detect endogenous thiols. Furthermore, The probe FR-thiol was suitable for time-dependent observation of biological thiols in living cells. Toward this end, cells imaging experiments were taken at different times showed that the fluorescence intensity in HeLa cells is time-dependent. It was worth mentioning that the cells were still alive after 30 min, which indicated that the probe FR-thiol was good permeability and minimum cytotoxicity. So it can be used for the detection of intracellular thiols.