The Preliminary Study Of Indocyanine Green(ICG)/Doxorubicin(DOX)Micelles For Cancer Theranostics

Objective:To prepare a theranostic micelle as a novel theranostic platform with multiple functionalities including cancer near infrared fluorescent imagingn(～800 nm),hyperthermia and synergistic cytotoxicity.Methods:(1)ICG,DOX and mPEG-b-PAsp(DA)were mixed in the mixture of methanol and triethylamine,and subsequently the solutions were evaporated using rotary evaporator,and then dispersed in water.Dynamic light scattering was used to measure the hydrodynamic diameter of micelles.The absorbance and fluorescent spectrums of ICG or DOX were measured using UV-Vis Spectrophotometer and Fluorescence Spectrophotometer,respectively.The drug release behavior of ICG and DOX was evaluated using dialysis method respectively,and free ICG/DOX in DMSO at pH 7.4 and 5.0 were used as the control.(2)A549 cells were used for tumor celles model in vitro.MTT method is used to evaluate the cytotoxicity of material,free ICG/DOX and micelles with or without photoirradiation.The flow cytometry was applied to explore the mechanism of endocytosis of micelles.Trypan blue staining was used to validate the cell death of different groups.DPBF fluorescence probe method,acridine orange staining and DHE staining were used to synergitic mechanism between chemotherapy and photothermed therapy.(3)A549 tumor-bearing BALB/c nude mice were established as the tumor model,and then in vivo fluorescence imaging technique was applied to investigate the distribution and imaging of micelles in nude mice bearing A549 tumor.(4)The antitumor effect of the ICG/DOX Micelles were evaluated using A549 tumor-bearing mice.Results:(1)The characteristics of the micelles:average particle size 71.4±6.9 nm,PDI:0.168.94.7%±0.8%ICG,82.3%±0.8%DOX were entrapped within the micelles at total drug loading level 40%.Preliminary experimental results show the stability of the polymer micelle of the particle size is relatively stable at 25℃.And the micelles have good stability in fluorescence and ultraviolet-visible absorption.Furthermore,we demonstrated the release behavior of ICG and DOX from ICG/DOX Micelles at pH 7.4 and 5.0 at 37℃.The micelles resulted in the sustained release of ICG and DOX when compared with free ICG/DOX,indicating that ICG/DOX Micelles are capable to minimize undesirable release in blood circulation.(2).In vitro experiments show that the ICG/DOX micelles have strong photothermal cytotoxicity under photoirradiation,and also display a synergistic effect.(3).NIRF imaging show that the ICG/DOX micelles have an enhanced biodistribution and imaging.(4).In vivo anticancer efficacy shows that the ICG Micelles group under photoirradiation can eliminate the tumor,but after a period of time the tumor will regenerate.DOX Micelles group can limited the tumor growth but it is hard to eliminate the tumor.The ICG/DOX micelles under photoirradiation can well eradiciate tumor,and inhibit the regeneration of tumor.Conclusions:In summary,we have developed a theranostic hierarchical micelles system for cancer NIRF imaging and multimodal synergistic therapy.The micelles achieve a high drug loading ang good stability via encapsulation of double bonds of ICG within hydrophobic cores.ICG/DOX micelles can improve cellular uptake,accumulation at tumor.The theranostic micelles have good cancer NIRF imaging capacity and superior anticancer efficacy.