Based On PCL-PEG-PCL Triblock Copolymer In Drug Delivery And Antigen Adjuvant System Research

Cancer is one of the diseases which threats human health.Chemotherapy,radiotherapy,and other treatments are currently used in clinic to suppress tumor proliferation and successfully prolong the life span of patients.However,more and more practices and researches founded that a single treatment form cannot eliminate tumor completely and prevent tumor metastasis.Therefore,to overcome the limitations of monotherapy,combination therapies using two or more forms of therapy have been proposed as an alternative type to monotherapy.Advanced nanotechnology enables the intelligent design of multifunctional nanomaterials used for co-delivery and co-assembly of two or more therapeutic agents,providing possibilities for the idea of combination therapy.Immunotherapy is a treatment that is completely different from chemotherapy.It regenerates the body ability to recognize and kill tumor cells by rebuilding or activating the patient's immune system and changing the tumor microenvironment.This treatment method does not damage the normal cells of the body,but it can inhibit the recurrence and metastasis of tumors and has long-term immune effect due to the existence of memory function.Therefore,it has received widespread attention.Polymeric nanoparticles have great power in integration of diagnostic and therapeutic agents.Great biocompatibility,biodegradability,flexible design and adaptability make it excellent drug delivery vehicle in cancer therapy.Amphiphilic block polymers structure depends on the proportion of the hydrophilic and hydrophobic blocks in the amphiphilic block as well as the polymer molecular weight.Therefore,based on the amphiphilic triblock polymer PCL-b-PEG-b-PCL,we obtained two materials that were self-assembled into polymer nano-vesicles and polymer nano-micelles by adjusting the ratios of PEG and PCL.Its application in chemotherapy-photothermal therapy and immunotherapy was explored.The details are as follows:1.LHRH/TAT dual-peptide and DOX/PTX/ICG multiple drug-loaded polymer vesicles for chemo-photothermal combination therapyIn this study,polymer vesicles were constructed based on reduction-responsive amphiphilic triblock copolymer PCL-ss-PEG-ss-PCL.Using thin film hydration and ultrasonic methods,we obtained polymer vesicles with homogeneous particle size distribution and coupled the aminated LHRH and cys-TAT on the outlayer of the vesicles.After loading chemotherapeutic drugs(DOX,PTX)and photosensitizer(ICG),the LHRH-/-TAT targeted polymer vesicles with the ability of combined chemo-photothermal therapy were successfully formulated.The polymer vesicles were characterized in terms of particle size,polydispersity dispersion,zeta potential(?),morphological structure,drug loading and entrapment efficiency,in vitro thermal imaging,and drug release.In addition,in vitro cellular uptake and cytotoxicity were performed to study the targeting efficiency and chemo-photothermal effect of the polymer vesicles.These studies indicated that the fabricated polymer vesicles can load different kinds of drugs with high drug loading content,trigger drug release in responsive to reduction environment,realize high cellular uptake via dual peptides,and achieve high cytotoxicities via chemo-photothermal combination therapy.2.Study on immunological properties of cationic lipopolymer micelles loaded with antigen and IMQ/MPLA dual adjuvantIn this study,we developed a new multi-functional LPNPs vaccine system that contains antigens and multiple TLRs for synergistic effects.Using OVA as antigen,TLR7 agonist IMQ and TLR4 agonist MPLA as adjuvants,cationic lipid polymeric micelles based on PCL-b-PEG-b-PCL and cationic lipids 1,2-dioleoyl-3-trimethylammonium propane(DOTAP)were prepared by thin film hydration and ultrasonic adsorption method for co-delivery both of antigen and agonists.The results showed that the cationic lipid polymer nanoparticles can significantly increase the uptake of antigen by DCs,effectively induce DCs maturation in vitro,and promote the migration of DCs to secondary lymph nodes in vivo.After subcutaneous vaccination of cationic lipid polymer nanoparticles loaded with OVA in mice,cross-presentation levels,secretion of cytokines,and long-term memory immunity were effectively improved and tumor was better prevented.3.DCs-targeted cationic polymer nanoparticles for co-transport of antigen and adjuvants and enhanced immune effectsThe polymer hybrid nanoparticles that target dendritic cells were prepared by linking mannose receptors.After antigen and adjuvant co-encapsulated,the DCs-targeted nanoparticles were assessed including morphological structure analysis,particle size analysis,in vitro release behavior,in vitro cytotoxicity assay,in vitro cellular uptake,in vitro maturation experiments,analysis of drug metabolism at the injection site,migration of DCs to secondary lymph nodes in vivo,animal immunization experiments,and prophylactic experiments.The results showed that the prepared co-transport antigen and adjuvant polymer nanoparticles have good biocompatibility,the ability of inducing maturation in vitro and can induce more antigen-specific CD8+ T cells,stronger lymphocytes activation,more efficient cross-presentation,and more memory T cells,antibodies,granzyme B,IFN-? and significantly delayed the development of tumors in mice.Therefore,DCs-targeted cationic polymer nanoparticles of this mixed adjuvant are a promising antigen delivery system for cancer immunotherapy.