Synthesis And Application Of Fluorescent Probes With Aggregation Induced Luminescence

Fluorescent bioimaging is considered as an indispensable technology in biological research,due to its high sensitivity,good spatio-temporal resolution,non-invasiveness,fast and real-time responsiveness,and light availability.Especially the advantages of fluorescent probes? strong specificity,high sensitivity,fast response and simple technology make them difficult to be replaced in biosensing and bioimaging field.The concept of AIE was proposed by Academician Tang Benzhong’s group,which is an unique phenomenon: fluorescent molecules do not emit or weakly emit,when dissolved in solution,but they are highly fluorescent as aggregates / clusters.The characteristics of AIE make AIEgens gifted in ?turn-on? fluorescence,when it spontaneously aggregates or binds to analytes in a hydrophilic environment,showing high sensitivity and excellent signal-to-noise ratio.Therefore,the fluorescent probe based on AIE shows great potential for application in fluorescent biological imaging.However,most of the fluorescent probes are organic molecules,which don?t have good biocompatibility and is easy to occur in water.So that it is not conducive to detection and imaging research,and at the same time the probes with a high specific targeting ability or response ability are scarce.Based on AIE materials,the fluorogens in my thesis are designed and synthesized with specific targeting response,and used for biological imaging and sensing research.Contents are as follows:1.Based on 9,10-distyrylanthracene and coupling with a polypeptide L5 whicht can target Glypican-3(GPC-3),a fluorescent probe molecule DSA-L5 was synthesized.Studies have shown that: DSA-L5 has typical AIE characteristics,and shows the strongest absorption peak position at 400 nm,and the strongest emission peak position at 550 nm.The luminescence of the molecule has a large stork displacement,which is beneficial to the research of biological imaging.the probe also has a high fluorescence efficiency.The introduction of quaternary ammonium salt and linked water-soluble polypeptide can effectively improve the biocompatibility of the probe.Cell experiments show that the probe can specifically recognize GPC-3 protein-expressing hepatoma cells and label it on the surface of the cell membrane;meanwhile,it shows low fluorescence when Co-incubated with other cancer cells and normal cells that lowly express GPC-3 protein.The signal indicates that the probe can effectively detect and image liver cancer cells overexpressing GPC-3 protein.The probe’s high specific targeting ability and biocompatibility demonstrate great potential in liver cancer detection2.Based on tetraphenylethylene,a new organic fluorescent dye TPE-2Indo was synthesized.TPE-2Indo shows typical AIE characteristics,with the strongest absorption at 420 nm and the highest emission peak at 560 nm.In the molecular design,the water-soluble indole group is connected to the derivative of tetraphenylethylene to increase its solubility in the aqueous phase.Based on the ability of indole groups to respond to pH,we studied the photophysical properties of molecules at different pHs and the morphological changes at different pHs.The experimental results show that the absorption and emission of the molecule will change strongly in different pH environments,and the pH range of the molecular response can cover 4-10,showing the application value of the probe in the pH substance detection response.