Design And Synthesis Of Poly(Amino Acids) For Immune Researches And Applications

As a newly cancer therapeutic method,immunotherapy has gradually developed into the fourth largest cancer treatment after surgery,chemotherapy and radiotherapy because of their safety,pertinence,persistence,systematicness,thoroughness and wide indications.Compared to conventional treatments,which directly kill both healthy and cancer cells,immunotherapy can more specifically target cancer cells and cause nearly no side effects.Recently,there are three main immunotherapies include cancer vaccine,checkpoint blockade therapy and chimeric antigen receptor-T immunotherapy.However,there are still some drawbacks in clinical application:1.in immune system,there are only a few antigen-presenting cells（APCs）,and the immune response can be stimulated only through the normal APCs.2.The tracking technology of the vaccine should be further improved during the treatment,which cannot provide more information for immunotherapy to guide clinical treatment.It impedes the further application of immunotherapy in clinical medicine.3.Ex vivo biopsy with immunohistochemistry is not appropriate for dynamic monitoring and assessing the PD-L1 heterogeneity.4.Only one immune treatment is not satisfactory at present in clinical treatment.Therefore,we aim to develop a series of delivery systems for immunotherapy.The thesis can be divided into four sections:1.Conjugated Polymer Brush Based on Poly（L-lysine）with Efficient Ovalbumin Delivery for Dendritic Cell VaccineIn this section,a water-soluble conjugated polymer brush（PPE-PLL）with high Ovalbumin（OVA）loading capacity was designed and synthesized.Due to the conjugated backbone,PPE-PLL was shown excellent photostability and light-harvesting ability.Moreover,the structural of Poly（L-lysine）（PLL）not only exhibited biodegradability,biocompatibility,and nontoxicity,but also had a strong interaction with OVA.The polymer brush was used as the carrier of antigen,and the PPE-PLL@OVA showed a higher cellular uptake in cells,whereas the antigen-pulsed DCs elicited strong immune response.Importantly,the DC vaccine improved the level of immune factor and inhibited the growth of B16F10 tumor.2.NIR-Ⅱ probe modified by poly（L-lysine）with efficient ovalbumin delivery for dendritic cell trackingIn this work,a new DC vaccine with in vivo tracking capability was developed.We designed and synthesized a second near-infrared window（NIR-Ⅱ）fluorescence probe（TTQ-PLL）with electron donor-acceptor（D-A）fluorescent core.TTQ-PLL can bind OVA effectively to form TTQ-PLL@OVA with great stability and water solubility.TTQ-PLL@OVA can be used to prepare DC vaccine,and the homing mechanism of vaccine can be monitored by NIR-Ⅱ fluorescence imaging.The NIR-Ⅱ probe provides possibilities in the development of trackable DC vaccine based immunotherapy.3.NIR-Ⅱ Fluorescent Molecular Bottlebrush Prepared by Ring-opening Polymerization for Programmed Cell Death Ligand-1 Checkpoint ImagingIn this study,a series of molecular bottlebrushes were designed and synthesized via a two-step“grafting from”strategy using ring-opening polymerization.Then we conjugated one of the molecular bottlebrushes(P（TTQ-F）-g-(PLL₃₀-g-（PGA）₅))with PD-L1 monoclonal antibody to afford（anti-PD-L1）-P（TTQ-F）-g-(PLL₃₀-g-（PGA）₅).Because of its excellent NIR-Ⅱ fluorescence ability and specific to the PD-L1 checkpoint,（anti-PD-L1）-P（TTQ-F）-g-(PLL₃₀-g-（PGA）₅)can be used for PD-L1targeting imaging in vivo.The results demonstrated that the molecular bottlebrush succeeded in targeting CT26 tumors with high PD-L1 expression level.4.NIR-Ⅱ Fluorescence Probe based on Polyamidoamine Dendrimers for Immunotherapy as Antigen CarrierIn this section,a NIR-Ⅱ fluorescence molecule（TTQ-F-PAMAM）was synthesized by modified polyamidoamine（PAMAM）dendrimers on D-A-D NIR-Ⅱ fluorescence core.TTQ-F-PAMAM can realize NIR-Ⅱ fluorescence imaging and showed outstanding photostability.Owing to the structure of PAMAM,TTQ-F-PAMAM showed great antigen-loading capacity.So,OVA can be adsorbed onto TTQ-F-PAMAM by electrostatic binding.TTQ-F-PAMAM@OVA can induce the maturation of DC and promotes specific anti-tumor immunity after DC uptake.DCs activated by the complex can release tumor necrosis factor-αand interleukin-12p70.This treatment strategy may greatly improve the efficiency of cancer therapy and provides a new method for immunotherapy research.