Anti-aggregation Cyanine Dyes Used In NIR-Ⅱ Imaging-guided Photothermal Therapy

The fluorescence imaging technology in the near-infrared two-zone biological channel(NIR-Ⅱ)has the advantages of low light scattering and weak auto-fluorescence.It can obtain high-spatial-resolution imaging in deeper biological tissues and achieve precise diagnosis at the location of the lesion.As a new cancer treatment method,photo-thermal therapy has the characteristics of obvious curative effect and small side effects.NIR-Ⅱ fluorescence imaging-guided photo-thermal therapy has shown great potential in the precise diagnosis and non-invasive therapy of cancer.The design and development of a new type of NIR-Ⅱ fluorophore with a longer excitation wavelength and improved photo-physical and solubility properties for use in clinical optical imaging-guided photo-thermal therapy have an attractive prospect.In the second chapter of this article,we synthesized a new hydrophilic quaternary ammonium stereo-cyanine dye(HQS-Cy).The sulfonic acid group on the small molecule probe HQS-Cy increases the water solubility of the dye,and the dimethyl ammonium functional group repels molecules through charge-charge interaction,destroying the planar feature of the cyanine structure,thereby increasing the distance between the molecules.Prevent the accumulation of HQS-Cy.And then,we prepared the amphiphilic polypeptide block-based nanoparticles HQS-Cy@P,which increased the water solubility of the dye,but also improved its biocompatibility and prolonged its circulation time in the body.The HQS-Cy@P nanoparticles have maximum absorption of 985 nm and maximum fluorescence emission of 1050 nm in an aqueous solution.HQS-Cy@P exhibits good photo-thermal stability and significant photo-thermal conversion efficiency(about 35.5%),In vivo and in vitro studies have shown that it is effective for NIR-Ⅱimaging-guided photo-thermal therapy system.In Chapter 3,we synthesized a new pH-sensitive peptide copolymer P(Glu-co-Lys)by the NTA method,using the pH dynamic response peptide of L-glutamic acid and L-lysine as a carrier for tumor cells The drug delivery system activated by external acid can self-assemble(pH 7.4)and disassemble(pH 5.5)under the adjustment of pH to load the drug and control its release.Load DOX and photo-thermal reagent HQS-Cy in the peptide copolymer to obtain HQS-Cy/DOX NPs for chemotherapy and photo-thermal combined therapy.Gentle photo-thermal heating can enhance the absorption of drugs by cells and enhance the efficacy of chemotherapy,and In addition,chemical-photothermal combination therapy can solve the defect of easy recurrence after photo-thermal therapy.The ingenious nano-drug delivery system of HQS-Cy/DOX NPs provides great potential for the improvement of chemo-photo-thermal therapy and will achieve excellent therapeutic effects in cancer treatment.