Design Of Fluorescent Sensor Systems And Their Application In Detection Of Biosubstances

Some biosubstances play important roles in organisms, the changes in these biosubstances’ levels have great implications in terms of physiological and pathological functions. So, detection and real time imaging of biosubstances are of significance. In this paper, four kinds of fluorescent sensors were developed based on different mechanisms. These sensors can detect(image in cells or in vivo) sulfide ion, γ-glutamyl transpeptidase and alkaline phosphatise respectively.First, for sulfide ion, we prepared the carbon dots(CD-S) modified with ligand moleculesas a probe precursor, which can coordinate with copper ions(Cu2+) to form a complex compound and the fluorescence of CD-S was quenched accordingly. The CD-S/ Cu2+ complex can detect sulfide ion with a LOD of 0.78 μM, as a turn-on fluorescent probe; S2- can capture Cu2+ from the CD-S/ Cu2+ complex and generate stable CuS(Ksp=3.63×10-36). With good water solubility, biocompatibility, selectivity and sensitivity, the probe can be successfully used in the detection for S2- in toally water and imaging in living cells.Second, we designed and synthesized fluorescent probe Glu-TPE, which can detect gamma-glutamine transpeptidase(GGT). As one of TPE derivatives, the probe Glu-TPE exhibits aggregation-induced emission(AIE) effect. The two γ-glutamine groups endow the probe Glu-TPE with good water solubility and biocompatibility. After GGT catalyzes the hydrolysis of γ-glutamine group in the probe molecule, enzymolysis leads to the formation of aggregate due to hydrophobicity and induces the AIE effect, which greatly enhances the blue fluorescence. Because of the specificity and efficiency of GGT enzymatic reaction, the probe Glu-TPE can be used to detect GGT in human serum samples and image endogenous GGT in A2780 cells with good selectivity and high sensitivity.Moreover, a fluorescent sensor PEG-NA-Glu based on ICT was developed for ratiometric detection of GGT. When the γ-glutamine group of the probe PEG-NA-Glu was hydrolysed by GGT,the change in the electron donating capability lead to the variation of the fluorescence emission.The probe PEG-NA-Glu shows high sensitivity(0.76 U/L) and biocompatibility, the probe PEG-NA-Glu can be used for detecting GGT in urine and serum samples with a convenient operation. And it also can image endogenous GGT in living cells with dual-color fluorescence.Finally, we successfully developed a robust fluorescent ratiometric probe AO-NA-P based on naphthalene imide derivatives, which features sensitive and selective detection of ALP in aqueous media and human serum samples with a LOD of 0.38 U/L. The excellent water solubility and good biocompatibility ensure the probe’s applicability in live cells and in vivo. Moreover, the probe can be employed to detect and image endogenous ALP elevation as a result of drug-induced organ damages to zebrafishes. The strategies herein may provide an effective approach for in vivo tracking of the variations of other biomolecules caused by drug-induced damages, which is of great importance for pathological analysis.