Synthesis And Application Of NIR-? Polymer Based On Cyclopentadithiophene

Biofluorescence imaging technology can be used for real-time stereoscopic imaging to visualize the detection of biomolecules,cells and tissues/organs,so that the detection results are more intuitive.Fluorescence imaging can track various physiological processes of organisms,which is of great help to researchers to understand and study relationship between the structure and function of biomolecules.The near-infrared(NIR)imaging technology,especially the second NIR window(NIR-?),has higher temporal and spatial resolution relative to the visible region,and has less damage to biological tissues,stronger penetration,higher sensitivity and less interference by background fluorescence.Compared with inorganic materials,organic polymer materials fundamentally eliminate the potential toxicity of heavy metals and are ideal for constructing NIR fluorescent probes.NIR-? fluorescence imaging has great potential in diagnosis,but its low quantum yield is an urgent problem.In order to improve the emission wavelength and quantum yield,we explored the structure-activity relationship of molecules,designed and synthesized a series of fluorescent polymers:(1)We adopt the design of donor unit-acceptor unit(D-A)to synthesize a new multifunctional polymer P-TT through coupling reaction.It has tetrahedral C(sp3)and branched alkyl chains in the main chain.This design is used to increase the steric hindrance between molecules and weaken the aggregation-caused quenching to obtain high quantum efficiency.The absorption peak and emission peak of P-TT are 686 nm and 1071 nm,respectively.The quantum yield of P-TT reaches 0.5% and can be heated to 49°C.under laser irradiation.PTT have been applied to liver NIR-? imaging in nude mice.(2)We improved the acceptor unit based on the design of the tetrahedral C(sp3).The polymer P-DPP was synthesized using the acceptor unit with stronger electron-withdrawing ability,while introducing another alkyl chain,which further increased the space resistance.The absorption and emission peaks of P-DPP are 763 nm and 1066 nm,respectively.The photothermal effect of P-DPP can reach 52 ° C and its quantum yield reaches 1.5%,which is three times that of carbon nanotubes(quantum yield 0.4%).P-DPP has been used for stable vascular fluorescence imaging and NIR-? imaging of nude mice,and has been successfully applied to photothermal therapy of tumors in nude mice.(3)In order to further reduce the size of nanoparticles and increase water solubility,we synthesized a water-soluble molecule F-DPP-F.We reduced the size through the design of D-A-D,and introduced PEG side chains to improve the steric hindrance and water solubility of its molecules.Its absorption peak and emission peak in water are 600 nm and 950 nm,respectively.And F-DPP-F has good biocompatibility.