Heparin Fluorescent Sensor Based On Poly(Pyridinium Salt)s

The detection and quantification of biological molecules have important implications forobtaining the information of human’s life activities, particularly the diagnosis and treatmentof the disease. Fluorescence analysis is more advanced in recent years, having vitalsignificance in many respects, including pharmaceuticals, clinic, environment, micrometricand trace analysis of foodstuff, and in every field of biological sciences research.As light sensitive materials, the cationic polymers have more distinct advantages thansmall molecule materials in recognizing the biological molecules, and they can amplify theoptical signal dramatically by the effect of molecular wires, which improve the sensitivities ofdetection tremendously. Therefore, the conjugated polymers have attracted much of thegeneral attentions in the recognition of biological macromolecules, developing rapidly.At present, the biological sensors based on cationic polymers are mainly side-chainmaterials, such as polyfluorene, polythiophene derivatives, and the hydrophobic groups suchas ammonium base salts and sulphonates will usually be brought in for their water solubility.Other than these conjugated polymers which have their hydrophobic groups in the side chains,in this paper, the poly(pyridinium salt)s are synthesized and characterized as novel main-chaincationic polyelectrolytes, in addition, the interaction of these poly(pyridinium salt)s withheparin was investigated by UV-vis spectroscopy and by fluorescence spectroscopysystematically. This thesis is divided into the following sections:Firstly, we synthesized conjugated cationic poly(pyridinium salt) P1by reaction of4,4’-(1,4-phenylene)bis(2,6-diphenylpyrylium) ditosylate and4,4’-diaminobiphenyl usingring-transmutation polymerization and confirmed it’s chemical structure and molecularweight by NMR spectroscopy and gel permeation chromatography (GPC). The interaction ofP1with heparin was studied by UV-vis absorption spectroscopy and fluorescencespectroscopy titration experiments in neutral aqueous solution (pH=7.40), and then thebinding constant and quenching constant is estimated to be2.90×104M-1and3.81×107M-1respectively. Furthermore, the selectivity experiments polymer P1was carried out, whichindicated the high specificity for heparin. In addition, we have studied the aggregationproperties of P1and heparin. The average particle size of P1and P1-heparin were92.0nmand190nm in the absence and presence of heparin, respectively. The dynamic light scattering(DLS) measurement indicated that the interaction of P1with heparin mainly includedelectrostatic interaction.We synthesized polymer P2and P3by reaction of4,4′-diaminodiphenylether/4,4’-diaminodiphenylmethane and4,4’-(1,4-phenylene)bis(2,6-diphenylpyrylium)ditosylate using ring-transmutation polymerization and confirmed their chemical structures byNMR as well. The binding constant of P2and P3is estimated to be1.31×106M-1and1.52× 106M-1in the aqueous solution (pH=7.40), according to the UV-vis absorption spectratitration method. We can obtain the quenching constant of P2and P3, which was estimated tobe1.02×106M-1and7.10×105M-1respectively, by the fluorescence spectroscopy titrationexperiments. In addition, the selectivity experiments of polymer P2and P3ware carried out,which indicated the high specificity for heparin. In addition, we have studied the aggregationproperties of P2and heparin. The average particle size of P2and P2-heparin were25.0nmand59.0nm in the absence and presence of heparin, respectively. The dynamic lightscattering (DLS) measurement indicated that the interaction of P2with heparin mainlyincluded electrostatic interaction.A new conjugated poly(pyridinium salt) containing carbazole derivant in it’s main chain(P4) was synthesized by reaction of4,4’-(1,4-phenylene)bis(2,6-diphenylpyrylium) ditosylateand3,6-diamino-9H-N-butylcarbazole using ring-transmutation polymerization and it’schemical structure was confirmed by NMR spectroscopy. The quantitative detection range ofpolymer P4to heparin was speculated to be0-14.0μM through the fluorescence titrationspectrum, which is confirmed to the dose level of the post operation and in the long-termtreatment (0.20-1.20U.ml-1--1.80-10.8μM). The fluorescence spectroscopy of P4based onits concentration was investigated: owing to the electronic interaction of them, the polymersexhibited aggregation, and inhibited P4conjugated intra-molecular rotation of main chain,which increased the polymer fluorescence, however, we don’t exclude the existence of theaggregation-induced emission (AIE) characteristics. Besides that, the selectivity experimentsand anionic interference experiment of polymer P4indicated the high specificity for heparin.We have known that P4we have synthesized can be applied in wide range of pH6-8by thefluorescence spectrum influenced by pH, indicating that it can be used in bio-system.