Application Of Fluorescent DNA Probe With AIE Characteristic For The Detection And Photodynamic Therapy Of Cancer

With the development of fluorescent materials,more knowledge could be acquired,enabling promoting the development of science as well as technology.In particular,we can better understand biochemical process as well as the functions of biomolecules by the utilization of fluorescent materials.However,conventional fluorescent materials were subjected to aggregation-induced quenching?ACQ?either at high concentrations or after agglomeration.Recently,a class of fluorescent materials with aggregation-inducing emission characteristic?AIEgens?have been developed,the weak fluorescence was observed in the good solvent.In contrast,the fluorescence significantly enhanced in the aggregation states due to the hindrance of the rotation of the AIE molecules.A series of probes have been reported for the detection of analytes and photodynamic therapy on the basis of fluorescent materials with aggregation-induced emission characteristics.However,combination with AIEgens and other therapeutic methods are still relatively rare for cancer treatment.This thesis was focused on the application of AIEgens.By taking advantage of the characteristics of aggregation-induced emission of AIEgens and AIEgens acting as photosensitizers,AIEgens have been explored for diagnosis and treatment of cancer.The thesis mainly includes the following three parts:?1?A DNA-conjugated aggregation-induced emission probe?TPE-R-DNA?was used for cancer tissue imaging and prognosis analysis on the basis of exonuclease III-aided target recycling technique.TPE-R-DNA consists of two parts:a hydrophobic long-wavelength aggregation-inducing emission molecule?TPE-R-N₃?as signal moiety;and DNA?Alk-DNA?which were specifically recognizing the hydrophilicity of MnSOD mRNA as recognition moiety.In the absence of MnSOD mRNA,negligible fluorescence was observed due to its good water solubility.Conversely,when the target was present,the target hybridized to the probe TPE-R-DNA to form a double strand.And then the TPE-R-DNA in the duplex was hydrolyzed by exonuclease III?Exo III?to produce the hydrophobic fluorophore.Subsequently,the hydrophobic fluorophore form aggregates in aqueous media,where bright fluorescence was observed.The detection limit of TPE-R-DNA toward MnSOD mRNA was as low as 0.6 pM.The fluorescent signal can be used to confirm the MnSOD mRNA expression level in cancer tissue.Moreover,the MnSOD mRNA expression in renal cancer was lower than in renal cancer adjacent tissue.In particular,the expression level was analyzed to predict prognosis of cancer patients.These results have demonstrated that low MnSOD mRNA expression of patients suffering from renal cancer appear to be related with a decreased survival time compared to those with a high level of MnSOD mRNA.?2?GSH-responsive MnO₂ was employed as vector to afford photosensitizers?TB?with aggregation-induced emission characteristics and DNAzymes for cancer imaging and photodynamic-gene combination therapy.Among them,TB is a photosensitizer with aggregation-induced emission characteristics which can be used for photodynamic therapy,while DNAzyme can degrade EGR-1 mRNA in the presence of Mn²⁺for gene silencing.In vitro experiments with tumor treatment have shown that MnO₂-DNAzyme-TB nanocomplexes?MDT?can be taken up by cells.Subsequently,MDT inhibits cell growth by gene silencing to reduce the expression of EGR-1.In addition,the released TB aggregated to form aggregates which enhanced the fluorescence.Moreover,singlet oxygen which were generated by TB further inhibit cell growth.The combination of photodynamic and gene therapy significantly improves the efficacy of tumor treatment.In vivo tumor therapy experiments show that MDT under illumination can effectively inhibit tumor growth in MCF-7tumor-bearing mice by photodynamic and gene silent combination therapy.?3?A positively charged SSNB with aggregation-induced emission characteristics can be used for the detection of telomerase activity and telomerase response photodynamic therapy.Based on the amplification of the primers caused by telomerase,the positively charged SSNB bind to the negatively charged amplified primer via electrostatic interaction,enabling the restriction of the intramolecular rotation of SSNB,therefore,the distinctive fluorescence was observed.SSNB can be applied for the determination of telomerase in various types of cancer cells.SSNB was also employed to distinguish between cancer cells and normal cells based on the difference in telomerase expression in cells.In addition,SSBN can also be used for highly selective and efficient telomerase response photodynamic therapy.