Construction And Evaluation Of CE6/DOX Combined Drug Delivery System Based On Photodynamic And Chemotherapy

Due to the uncontrolled abnormal cell proliferation and unobservable cell metastasis,cancer has become one of the most serious health problems in the world.Chemotherapy is the main clinical treatment method for tumors.The side effects of chemotherapeutic drugs are very important issues.These side effects include but are not limited to severe systemic toxicity and the development of drug resistance.To address the mentioned drawbacks of chemotherapy,the development of nano drug delivery systems and the co-delivery of multiple therapeutic agents have emerged as alternatives.Nano drug delivery systems can achieve the specific release of chemotherapeutic drugs at the tumor;and the synergistic effect of multiple therapeutic agents may lead to improved tumor suppression efficiency,reduced adverse reactions,and even eliminated the generation of drug resistance.In this study,activated polyethylene glycol was used as a carrier,and the chemotherapeutic drug doxorubicin and the photosensitizer chlorin e6 were combined to realize the combination of chemotherapy and photodynamic therapy.The conclusions are as follows:（1）Firstly,the water-soluble macromolecular polyethylene glycol(m PEG₂₀₀₀)was activated by phenyl p-nitrochloroformate（NPC）and hydrazine hydrate（NH₂NH₂·H₂O）to obtain the drug carrier（m PEG-hyd）.Then,doxorubicin（DOX）was bonded to the carrier with a p H-sensitive hydrazone bond to obtain an amphiphilic prodrug（m PEG-hyd-DOX）.Proton nuclear magnetic resonance spectroscopy,infrared spectroscopy and ultraviolet spectroscopy verify the structure of each intermediate and prodrug.As the ratio of drug to carrier increases,the amount of drug loaded increases and the grafting rate also increases.（2）Single-drug nano delivery system M（DOX）were obtained by ultrasonic self-assembly method,and the photosensitizer chlorin e6（Ce6）was loaded into the hydrophobic core of the nano delivery system to prepare dual-drug nano delivery system.The effect of the feed quality ratio of single-drug nano delivery system and Ce6on the drug loading and encapsulation efficiency of the prepared co-administered nano delivery system was explored,and the optimal conditions were determined.The particle size of the co-administered nano delivery system is about 185.0 nm,and the monodispersity performance is good;during the in vitro stability test,there is almost no change in particle size and particle size distribution,and the co-administered nano delivery system have good stability;during the drug release research process,the co-administered nano delivery system showed acid-sensitive drug release behavior,with73.03%of DOX and 68.98%of Ce6 released within 48 h.The active oxygen generation performance was evaluated.（3）He La cells were selected to investigate the in vitro anti-tumor activity of the nano delivery system,and L929 cells were selected to investigate the toxic and side effects of the carrier and nano delivery system on normal cells.Under light conditions,the dual-drug nano delivery system showed obvious cytotoxicity aganist He La cells(IC₅₀ was 0.31μg/m L and 0.39μg/m L,respectively),and less toxic and side effects on L929 cells(IC₅₀ was 0.91μg/m L and 1.41μg/m L,respectively),and the two therapies showed a good synergy（CI<1）.In the cell uptake experiment,the co-administered nano delivery system could be successfully taken up by cells.The cellular uptake behavior was further verified by flow cytometry.In the cell reactive oxygen species detection experiment,obvious reactive oxygen species production was observed.Mitochondrial membrane potential detection results showed that DOX and ROS generated by Ce6could induce mitochondrial structural damage and eventually lead to tumor cell apoptosis.