| Water-soluble conjugated polymers (WSCPs) have attacted much attention because of their good light-harvesting ability and molecular wire effect, thus exhibit the broad applications in biological detection, disease diagnosis, drug transport and release, cell imaging, microbial and tumor destruction. Compared with small molecules, water-soluble conjugated polymers with signal amplification effect can greatly improve the detection sensitivity. In this thesis, the synthesis of cationic poly(fluorenylene phenylene)(PFP) and DNA-OPE hydrogel and their applications in drug screening and controlling antibacterial activity have been studied, respectively. The results are summarized as followed.1. Novel Fluorescent Biosensor for α-Glucosidase Inhibitor Screening Based on Cationic Conjugated PolymersA new fluorescent biosensor has been designed to screen a-glucosidase inhibitors (a-GIs) sensitively by utilizing signal amplification effect of conjugated polymers. The fluorescence of cationic poly(fluorenylene phenylene)(PFP) is quenched in the presence of p-nitrophenyl-α-D-glucopyranoside and a-glucosidase, and turn on upon addition of a-GIs. Thus, α new method has been developed for α-GIs screening based on the fluorescence turn-off/turn-on. The IC50values obtained for inhibitors were compared with that reported using absorption spectroscopy. Several α-Gls such as2,4,6-tribromophenol,3-butylidenephthalide and acarbose were also used to examine their inhibitory effects via the new method. The fluorescence turn-on induced by2,4,6-tribromophenol is more efficient than those caused by other two inhibitors, which indicates the inhibitory ability of2,4,6-tribromophenol is the strongest among the three inhibitors. The results are consistent with that reported in literatures. The IC50values obtained for2,4,6-tribromophenol and3-butylidenephthalide are about0.037mM and0.21mM, respectively, which are lower than that reported using the absorption spectroscopy (IC50for2,4,6-tribromophenol and3-butylidenephthalide were60.3μM and2.35mM, respectively in literatures). It is promising that the novel sensor can sensitively and real time screen new effective α-GIs in vitro. Furthermore, it provides a new assay model for enzyme activities detection and inhibitors screening of other enzymes (such as a-galactosidase and β-glucuronidase).2. Regulation of Antibacterial Activity Based on Fluorescent DNA-Oligo(Phenylene Ethynylene) Hybrid HydrogelA novel DNA-conjugated oligomer composite hydrogel has been designed, prepared and characterized by scanning electron microscopy and fluorescence microscopy. Its antibacterial activity and regulable antibacteria driven by DNase have been explored. Notably, in this new material, the DNA is used as the frame of the hydrogel and retains biocompatible aspects, and conjugated oligomers OPEs are used as the photosensitizer and retain their optical properties but no antibacterial activity in the gel state. Once irradiating the mixture of the GEL and Gram-negative E. coli, singlet oxygens are produced and released in the system. Because of the failure of affinity of negatively charged bacteria and negatively charged DNA-OPE hydrogel, the singlet oxygen can’t kill E. coli. With the addition of the DNase, the DNA-OPE hydrogel was hydrolyzed by DNase into small fragments even single nucleic acid base and OPEs. The free OPEs are able to permeate into the membrane of E. coli, and then E. coli bacteria are killed by the singlet oxygens induced under irradiation. Thus, the antibacterial activities of hydrogel can be monitored by DNase. Furthermore, it is potential to develop a new way for drug controlled release based on the new material and regulation method. |
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