DNA Detection Based On Conjugated Polymers And Design Of AIE Photosensitizer

Water-soluble conjugated polymers have attracted extensive interest from scientific researchers,because of their special optical properties.Compared to small molecule counterparts,the large number of photoactive units on the polymer chain increases the possibility of light absorption.The excitation energy along the entire backbone of the conjugated polymer is transferred to the energy/electron acceptor,resulting in amplification of the fluorescent signal.Therefore,conjugated polymers can be used as optical platforms in high sensitivity chemical and biosensors.Not only water-soluble conjugated polymers can be used for fluorescence sensors,but also conjugated compounds with aggregation-induced emission(AIE)can be used for the sensing platform.In many conventional systems,luminaries experience some effects,which are partial or full emission quenching.However,AIE materials precisely overcome the disadvantages of aggregation-caused quenching(ACQ).In the process of AIE,non-emissive emitters induce emission through aggregate formation.Since the concept of AIE was first proposed in 2001,this field has attracted great research interest in the academic and technical fields,and has brought a variety of diversified AIE probes.AIE materials are widely used in biological probes,chemical sensing,cell imaging and tumor therapy.Mainly carried out the following aspects of the work:(1)DNA detection based on conjugated polymer and enzyme digestion cycle reactionConjugated polymers and fluorescein for labeling DNA serve as donors and acceptors for fluorescence resonance energy transfer,respectively,and the emission spectrum of the conjugated polymer coincides well with the absorption spectrum of fluorescein.The electrostatic interaction between the positively charged conjugated polymer and the negatively charged DNA strands brings the distance between the conjugated polymer and the fluorescein closer together,leading to efficient fluorescence resonance energy transfer.The target DNA can trigger the Exonuclease ? to degrade the probe strand and release the fluorescein linked to the probe strand.The fluorescence resonance energy transfer between the free fluorescein and the conjugated polymer cannot occur.The target DNA cyclic hybridization induces the release of a large amount of fluorescein to achieve amplification of the fluorescence signal.The experimental method is simple to operate,with good selectivity and high sensitivity.(2)Photoresponse of AIE materials to glutathione(GSH)The AIE material emits intense fluorescence in the aggregated state,overcoming the disadvantages of fluorescence quenching caused by common material aggregation.Firstly,the synthesis route of AIE materials was designed,and then the near-infrared AIE materials were prepared according to the synthetic route.The synthesized materials were characterized.The synthesized AIE material was made into a nanosphere that was dissolved in an aqueous solution by polymerization,so that it was dispersed in an aqueous solution and emitted weak fluorescence.After addition of glutathione(GSH),GSH can break the disulfide bonds on the nanospheres,open the nanospheres,and release the AIE material.The AIE material accumulates in the aqueous solution and emits strong fluorescence,accompanied by a large amount of singlet oxygen,showing good photodynamic performance...