| Near-infrared cyanine dyes have been widely used in the diagnosis and photothermal therapy of tumors.The cyanine dyes could absorb near-infrared light of a specific wavelength and thus transition to an electronically excited state.Some of the excited-state energy is released in the form of near-infrared fluorescence and can be effectively used for imaging of living tumors.The other part of the excited state’s energy is transferred to heat through vibrational relaxation or other non-focal transitions.Due to the abnormal angiogenesis inside the tumor,it loses its self-regulatory effect after being heated,resulting in difficulty in its heat dissipation and a gradual increase in temperature.When the temperature exceed the range of tumor cells,tumor cells would be killed.Therefore,the near-infrared cyanine dyes can also be used as photothermal agents.As one of the special properties of solid tumors,hypoxia is closely related to the diagnosis and treatment of tumors.The diagnosis and photothermal treatment reagent for tumor hypoxia design of tumor can not only reduce the toxic and side effects on normal cells,but also be able to achieve precise treatment of tumor site.In the first part,a hypoxia-activated near-infrared fluorescence probe HCy-NO2 was constructed by substitution,Vilsmeier,condensation and cracking reaction,with the hemicyanine dye as a fluorescent group and 4-nitrobenzyl ether as the hypoxia-responsive group.The structure of the probe was characterized by NMR and MS.The reduction mechanism of the probe was studied by HPLC,and the selectivity and sensitivity of the probe were evaluated by UV and fluorescence spectra.The effect of HCy-NO2 on MCF-7 cell viability under normoxia and hypoxia were evaluated by MTT method,and the hypoxia process of the cells by confocal fluorescence imaging method was used.The results showed that the maximum absorption wavelength and maximum fluorescence emission wavelength of HCy-NO2 in DMSO were 686 nm and 740 nm respectively.HCy-NO2 had high selectivity for nitroreductase（NTR）,the detection limit was 15.6 ng/m L,the response time was 15 min,nontoxic,and it could be effectively activated in the hypoxia or NTR detection in the tumor hypoxia region.In the second part,using 1,1,2-trimethyl-1H-benzo[e]indole as raw material,the IR825-NO2,IR825-OCH3,and AsyCy-NO2 which have similar structure to IR825 were synthesized by substitution,Vilsmeier and condensation reaction,introducing 4-nitrobenzyl group,methoxy group,and nitro group.The structure was characterized by NMR and MS and the stability was evaluated by UV absorption spectroscopy.The effects of IR825-NO2,IR825-OCH3,and AsyCy-NO2 on the viability of 4T1 cells under different conditions were investigated using the MTT assay.The photothermal conversion efficiency was evaluated in vitro and the effect of photothermal treatment was evaluated by in vivo experiments.The results showed that,compared with ICG,IR825-NO2,IR825-OCH3 and AsyCy-NO2 had better photostability and thermal conversion efficiency.IR825-NO2 in the dual factors of hypoxia and near-infrared light showed highly toxic and hypoxia selectivity.IR825-NO2could effectively inhibit the growth of tumor after near-infrared laser irradiation,and the tumor inhibition rate was 66.5%,which provides a new idea for selective tumor photothermal treatment. |
