Construction Of Intelligent Drug Delivery System And Their Antitumor Application

Cancer is one of the most critical diseases that seriously threaten human health.So far,the basic and clinical researches on the benefits of cancer treatment is still urgent.As one of the main methods of cancer treatment,chemotherapy exhibits adverse side effects due to the lack of tumor specificity of chemotherapy drugs on normal cells and organs,which seriously affect the therapeutic effect and clinical application of chemotherapy.The rapid development of nanotechnology has allowed a variety of therapeutic drugs to be loaded into nanoparticles,which offer new hope for the treatment of cancer.Compared with free drugs,drug delivery system(DDS)has many advantages.Due to the enhanced penetration and retention(EPR)effect,DDS can regulate the biological distribution of drugs in the body and promote the accumulation of drugs at the target sites,thus improving the therapeutic effect of tumor and reducing the toxic side effect.Although nanomaterials can be passively enriched in tumor sites through EPR effect,the effect of the passive targeting is quite depending on tumor angiogenesis.Meanwhile,the type and size of the tumor also have a serious impact on the final effect of passive targeting.DDS with an actively target and specifically kill tumor cells function has attracted great attention by the researchers.Therefore,the construction of DDS using bioactive ligands that can interact with the tumor microenvironment to realize the targeted delivery to the tumor cells and then release the drug responsively,has attracted considerable attention in the cancer therapy.Albumin can actively target tumor by binding to GP60,and it can be easily modified by tumor target ligands to achieve tumor cell targeting ability,since its surface has abundant functional groups such as amino,carboxyl,and sulfhydryl groups.The carrier-free nanodrugs can also effectively target tumor cells by surface modification during or after the formation of the nanoparticles.However,the albumin and carrier-free DDSs often have unsatisfactory curative effects in the treatment of tumors.In general,chemotherapy drugs do not have good sensitivity to all tumor cells,and a single way of treatment will also lead to the treatment effect of cancer is not as expected.Therefore,it is urgent to develop a multi-functional targeted DDS to improve the antitumor effect.This dissertation aims to improve the targeting effect of chemotherapeutic drugs and the therapeutic efficacy of tumors.Albumin nanoparticles and carrier-free nanodrugs were selected to construct several DDSs for the delivery of chemotherapeutic drugs and related molecules,and the biological effects of DDSs related to tumor were also evaluated.The main research results are summarized as follows:(1)Redox-responsive amphiphilic camptothecin prodrug nanoparticles for targeted liver tumor therapyIn order to improve the chemotherapy drug loading capacity and the targeting ability of nanoplatforms for cancer treatment,we use chemotherapy drug camptothecin(CPT)and liver cancer targeting molecule lactose(LA)to synthesize a carrier-free prodrug nanoplatform CPT-S-S-LA.CPT and LA are linked by disulfide bonds which can be broken by high concentration of glutathione(GSH).The amphiphilic small molecule is composed of the hydrophobic CPT and the hydrophilic LA,it can be self-assembled into nanoparticles with a particle size around 110 nm.The nanoparticles can firstly be enriched at the tumor site by the EPR effect,and then internalized by the tumor cells through the asialoglycoprotein receptor mediated endocytosis,finally release the antitumor drug CPT by the high concentrations of GSH in the tumor cells.Drug release experiments confirm that the nanoparticles have the GSH-stimuli drug release behavior.Meanwhile,in vitro studies show that the nanoparticles have the specific recognition ability of target liver cancer cells instead of normal HUVEC cells.Finally,both in vivo and in vitro results prove that the targeted carrier-free nanodrugs have enhanced tumor inhibition ability comparted with the free chemotherapeutics.(2)Nanoparticle-facilitated autophagy inhibition of tumor cells for improved chemotherapeutic effects on glioblastomaIn order to further enhance the antitumor effect of chemotherapy,we combine autophagy inhibition of glioma stem cells with chemotherapy to improve the sentisivity of glioma cells to chemotherapy drugs.We select albumin as the drug carrier to penetrate the blood-brain-barrier through nutrient transporters.The synthetize of the albumin nanoparticles is through de-solvent method,then folic acid is modified on the surface of the albumin nanoparticles via amide reaction to enhance the phagocytosis of glioma cells.The chemotherapy drugs paclitaxel(PTX)and the autophagy inhibitor chloroquine phosphate(CQ)are then loaded into the albumin nanoparticles for the combination treatment.The results indicate that we have successfully prepared albumin drug-loaded nanoparticles,and the nanoparticles can effectively penetrate the BBB model and further target glioma cells in vitro.We find that the gene expression of stemness-related genes in glioma cells treated with PTX alone are significantly upregulated,but decreased sharply when combined with CQ,suggesting that the inhibition of autophagy can effectively improve the sensitivity of glioma cells to the chemotherapy drug PTX.Cell viability and cell apoptosis results also verify that the autophagy inhibitor CQ can increase the sensitivity of glioma cells to PTX,and the nanodrug delivery system can further promote the anti-glioma efficiency.Next,we knock down the autophagy associated gene ATG5 of the glioma cell to further confirm that the inhibition of autophagy can improve the sensitivity of glioma cells to PTX.(3)Constructing nanocomplexes by multicomponent self-assembly for curing orthotopic glioblastoma with synergistic chemo-photothermal therapyIn order to further enhance the effect of tumor chemotherapy,we combined tumor photothermal therapy with chemotherapy.Firstly,CPT is modified with amino acids to obtain the prodrug CPT-RT,and the prodrug can be assembled with IR783 into stable nanoparticles via π-π stacking and hydrogen interaction.Next,we synthesized polylysine(PLL)by polymerization,then reacted with PEG and Aniopep-2 to obtain the three component Ang-PEG-g-PLL.Then negative charged two-component nanoparticles(CI)can be covered by the positive charged Ang-PEG-g-PLL through electrostatic interaction to obtain the three-component nanoparticles APCI.Both in vivo and in vitro studies confirmed that the nanoplatform can effectively penetrate the blood-brain-barrier and then target glioma cells.Cell viability and apoptosis results have also confirmed the synergistic combination effect of chemotherapy and photothermal therapy in the glioma treatment.Finally,in vivo results showed that APCI + Laser could significantly inhibit the growth of the tumor and prolong the survival time in the glioma-bearing nude mice.