Construction Of A Dual-responsive Liposome Drug Delivery System Targeting Liver Cancer Based On Tumor Microenvironment

Liver cancer is a malignant tumor that occurs in the liver.Due to the difficulty of early diagnosis,rapid progress and lack of targeted drugs,the survival rate of liver cancer is extremely low.It is currently one of the most serious diseases threatening human health.When traditional chemotherapy drugs are used for treatment,they are often accompanied by severe side effects,which greatly limits their therapeutic effects.Nanomedicine has shown greater potential in improving drug bioavailability,controlling drug release and targeting tumors,providing a new direction for overcoming the shortcomings of traditional chemotherapy drugs and improving the efficacy of chemotherapy.Therefore,this thesis constructed GSH / ROS dual-responsive drug livery systems using reactive oxygen species responsive adriamycin prodrug(BDOX)as the model drug,aiming for targeting to liver tumor.This thesis includes the following three aspects:(1)Construction of GSH/ROS-responsive liposome drug delivery system targeting to liver cancer cells(BDOX/GAL-SS-LIP).Firstly,galactosylated lipid with disulfide bond(GAL-SS-Lipid)was synthesized by esterification of glutamic acid and tetradecanol as hydrophobic part,lactonic acid as hydrophilic part and cystine containing disulfide bond as linker.In addition,doxorubicin prodrug(BDOX)with phenylborate structure was synthesized with doxorubicin as raw material.BDOX,GAL-SS-Lipid,cholesterol and lecithin were mixed in a certain proportion and prepared into drug loaded liposomes to obtain nano-particle with uniform size by a membrane hydration method.The results of IR,NMR and MS showed that the lipid and doxorubicin prodrug were successfully synthesized.The results of liposome performance test show that the particle size of the synthesized liposome is between 100-200 nm,the particle size is relatively uniform,and the zeta potential is between-15 m V and-20 m V with good stability.The entrapment efficiency of liposomes is more than70%.The results of in vitro release show that liposomes had GSH response ability.The results of cell uptake show that BDOX/ GAL-SS-LIP exhibits weak targeting to normal cells L-O2 cells but better targeting to hepatoma cells(HepG2 cells).In addition,the cytotoxicity results show that BDOX displays strong toxicity to HepG2 cells and reduced toxicity to normal hepatocytes.The prepared blank liposomes have good biocompatibility.Liposome entrapment of drugs not only reduce the toxicity to normal hepatocytes,but also maintain strong cytotoxicity to liver cancer cells.(2)Construction of a drug delivery system containing ROS-responsive adriamycin prodrug and GSH/ROS dual-responsive targeting liver cancer cells.In this system,galactosamine was used as the hydrophilic part of lipid monomer to synthesize galactosylated lipid(GAL-S-Lipid)with sulfide bond.The structure of GAL-S-Lipid was characterized by NMR,MS and IR.Liposomes were prepared by the film hydration of lipids and prodrugs.The particle size of liposomes iss about 100 nm,the zeta potential is about-15 m V to-19 m V,and the entrapment efficiency iss more than 75%.The results of cell uptake show that DOX/GAL-S-LIP exhibits weak targeting to L-O2 cells but stronger targeting to hepatoma cells(HepG2 cells).The drug released in the presence of ROS/GSH is greater than in the absence.The cytotoxicity results show that the prepared blank liposomes shows good biocompatibility.The ROS/GSH responsive liposome loaded with BDOX not only reduces the toxicity to normal hepatocytes but also improve the cytotoxicity to hepatoma cells(HepG2 cells).(3)A GSH/ROS dual-responsive galactosylated liposome loaded with vitamin K3 and doxorubicin prodrug bdox was constructed.The particle size of the liposomes was about 100 nm,and the distribution was relatively uniform.The zeta potential was between-15 mv and-20 m V,and the entrapment efficiency was more than 70%.The results of liposome uptake by HepG2 and l-o2 showed that BDOX/GAL-C-LIP,BDOX/GAL-C-LIP/VK3,BDOX/GAL-S-LIP,BDOX/GAL-S-LIP/VK3 exhibit weak targeting to normal cells(L-O2 cells)but stronger targeting to liver cancer cells(HepG2cells).The cytotoxicity test results showed that the presence of VK3 in the drug delivery system significantly improved the cytotoxicity to HepG2 cell,in compared with the system only loaed with BDOX.