Construction Of Nano-targeted Drug Delivery System Based On Click Chemical Reaction And Its Theranostic For Breast Cancer

Tumor has been an important threat to human health due to multiple factors,such as human life pressure and environmental pollution.In traditional drug therapy,targeted tumor marker strategies require covalent linking of a targeting moiety to an NIR fluorophore or drug carrier by various bioconjugation strategies.However,because of the high molecular weight of imaging agents or drug carriers,the steric hindrance effect of this method greatly affects the targeting efficiency of targeting ligands in vivo,thereby reducing probe availability,imaging contrast and tumor retention time.In order to solve this problem and achieve high sensitivity detection and specific targeting of tumors,we use the concept of bio-orthogonal as an efficient and rapid spontaneous reaction to label liposomes loaded with near-infrared cyanine dyes and integrin?_v?₃ targeting polypeptide RGD,respectively.The new labeling method evades the steric hindrance caused by the connection between probe and target molecule,which greatly improves the tumor targeting ability of probe,and makes it have more efficient detection sensitivity and better PTT/PDT therapeutic effect on tumors.The main innovations of this paper are summarized as follows:1.A lipid-soluble cationic near-infrared heptamethylene cyanine dye CyBI7 was synthesized by one-step synthesis.The maximum absorption peak of the dye is 818 nm,the fluorescence emission peak is 837 nm,and the emission wavelength extends to 1150 nm in the near infrared region.Because CyBI7 is a fat-soluble cationic dye,it can penetrate the cell membrane more easily than ICG,and prolong its cell retention time.It is helpful to reduce the dosage of probe in biological imaging and treatment,thus reducing the biological toxicity and side effects.2.In order to realize the high sensitivity of near-infrared fluorescent probe in the diagnosis of tumors and PTT/PDT treatment,CyBI7 dyes were loaded into liposome phospholipid bilayers?CyBI7-LPs?by liposome drug delivery system,so as to improve the in vivo circulation ability and biocompatibility of dyes.At the same time,in vitro PTT/PDT results showed that CyBI7 had better photothermal effect than other cyanine dyes?ICG,IR780?.Liposome nanoprobe CyBI7-LPs had better photostability and PTT/PDT performance than free dye CyBI7.This liposome drug delivery system has excellent biocompatibility and PTT/PDT effect,which is conducive to cell and in vivo tumor imaging and PTT/PDT combination therapy.3.In order to achieve high sensitivity and specificity of cancer detection,further improve the targeting efficiency of nanoprobes in vivo,and increase the uptake of dyes in tumor tissues,with the help of the concept of bio-orthogonal reaction,we used 4T1 breast cancer as the research model and clicked non-destructive markers on CyBI7-LPs and targeted polypeptide RGD?integrin?_v?₃ specifically recognizing the overexpression of tumor cells?.Cell and in vivo tumour imaging results showed that click-mediated liposome nanoprobes?Click LPs?could accumulate in tumors in only 5 minutes by using RGD pre-target and nanoprobe post-labeling,and the fluorescence intensity was significantly higher than that of other labeled dyes.Because of the high sensitivity of near infrared fluorescence probe,Click LPs can detect 2 mm small tumors with a signal-to-noise ratio of6.8.The dye can accumulate in the mitochondria by targeting the negative transmembrane potential in the mitochondria.Under near infrared light,the heat and reactive oxygen species produced by the dye CyBI7 can be used in the combination therapy of PTT and PDT to inhibit the growth of tumors,prevent drug resistance and recurrence of tumors.In conclusion,click-mediated liposomes can improve the biocompatibility of small molecule near-infrared fluorescent probes,enhance their targeting specificity to 4T1 breast cancer,improve the photostability of probes and PTT/PDT effect.It can be used as a highly sensitive nanoprobe for diagnosis and treatment of breast cancer,and achieve the effect of early diagnosis and precise phototherapy.