Synthesis Of Fluorescent Probe Based On Polyethylene Glycol And Its Functions

Fluorescence detection techniques has been widely used in the areas of biology, medicine,chemistry and materials science, due to its simple, high sensitivity, specific selectivity, lowdetection limit, real-time and in-situ in vivo. As a kind of derivative of fluorescein,fluorescein isothiocyanate(FITC) has high molar extinction coefficient, high quantum yield,no side effects, and low cost. Furthermore, its excitation and emission wavelengths are in thevisible region. However, it has its own shortcomings, such as the poor cell membranepermeability resulted from the poor lipophilic feature, so that its effect is not good when it isapplied in the intracellular research. It is well known that methoxypolyethylene glycolamine(PEG) is a hydrophilic polymer. So far, PEG has been extensively used in biomedicalapplications, due to its non-toxic, non-antigenic and non-immunogenic properties. Moreover,2,4-dinitrobenzenesulfonyl moiety is able to efficiently quench the fluorescence of thefluorophores upon being coupled onto the fluorophores, while nucleophilic reagent can cleave2,4-dinitrobenzenesulfonyl group, which will restore the fluorescence of the fluorophoressystem. Therefore, in this study, we chose the fluorescein isothiocyanate as a fluorophore and2,4-dinitrobenzenesulfonyl as receptor unit, and incorporate the methoxypolyethylene glycolamine onto the fluorescein isothiocyanate. And we synthesize a fluorescence turn-on probebased-on PEG with good water solubility, good cell membrane permeability and low toxicity.Finally, the probe is used in the detection of an analyte in pure aqueous solution and livingcells. The main contents and the results of this paper are as follows:(1) The water-soluble fluorescence turn-on probe based-on PEG was successfullyprepared, and its structure, spectroscopic properties and cytotoxicity were investigated. Theresults show that, the synthesis of the probe is simple, the water solubility of the probe isgreatly improved by PEG, and the cytotoxicity of the probe is low when its concentration is10-2mg mL-1. We chose the10-2mg mL-1as test concentration.(2) The function of the probe used in the sulfide anion detection, including the responsemechanism of the probe toward sulfide anion, spectroscopic performance of the probe treatedwith sulfide anion, the response of the probe toward sulfide anion in running water and theapplication of the probe in living cell imaging were investigated experimentally. The results show that, the cleavage of2,4-dinitrobenzenesulfonyl group results in fluorescenceenhancement of the probe in the presence of sulfide anion, and with the increasing of thesulfide anion concentration, the fluorescence intensity of the probe solution is graduallyincreased. The fluorescence intensity of the probe solution is enhanced to340times at518nmwhen the concentration of sulfide anion is15μM. Furthermore, the detection limit of theprobe is as low as150nM, it has specific selectivity, fast response within10minutes. Moreimportantly, the probe may be well applied in the detection and tracking of sulfide anion inrunning water and living cells respectively because of its excellent water solubility, cellmembrane permeability and little cytotoxicity.