Engineering Functional Nanomaterials For Regulating The Function Of Cell-surface Receptors

Cells interact with external environments mainly through protein receptors expressed on the membrane.These cell membrane receptors participate in various life activities such as cell growth,development,metabolism,nerve response,and immune response.The dysfunction in information processing of cells is closely related to the occurrence and development of diseases,such as diabetes,autoimmune diseases,and cancer.Therefore,the correct and moderate response of cells to external information is an important guarantee for the normal progress of cell life activities.Regulates the function of cell membrane receptors artificially may play an important role in cell-related biological processes,disease diagnosis and treatment.At present,according to the different objects of manipulation,the strategies of regulating the function of cell membrane receptors can be divided into two types.The first type uses ligand molecules as manipulation objects to regulate the function of cell membrane receptors indirectly.For example,cytokines are messenger molecules of immune cells.Changing the concentration and distribution of cytokines in the microenvironment outside the cell membrane can regulate the activation intensity and function of the corresponding cell membrane receptors.Although the use of specific ligand molecules can regulate the functional behavior of cells,it may cause systemic toxic side effects.The multivalent ligands developed based on DNA nanotechnology can regulate the function of cell membrane receptors by adjusting the distribution or abundance of the ligands.They also have many limitations such as require chemical modification,interferes with the natural state of the ligand easily,and complex operations.Therefore,it is of great research significance to develop regulatory methods that can operate simply,control the local release,and does not affect the ligand structure.The second type takes the cell membrane receptor itself as manipulation objects,and directly regulates the function of the cell membrane receptor by changing the expression,structure,or distribution of the receptor.For example,genetic engineering,which has been widely used in protein expression.At the same time,it has made remarkable achievements for regulating the function of cell membrane receptor.However,the shortcoming,such as the genetic modification process was complicated,and might cause disturbance on natural cellular states,have greatly hindered its application.DNA nanotechnology regulates the function of cell membrane receptors by controlling their distribution and aggregation state,but it is limited to the regulation of existing membrane protein receptors.At the same time,researchers have developed a variety of chemical structures that can be embedded in membranes to simulate the function of cell membrane receptors,but they are all limited to simplified cell models and cannot achieve real cell behavior regulation.Therefore,the development of chemically synthetic membrane receptors that can work in a real cell system to coordinate the interaction between cells and the outside world is a very challenging topic,and it will also provide a new way of thinking about cell regulation.Aiming at many problems existing in the current methods of regulating the function of cell membrane receptors,New functional nanomaterials have been developed to tailor-regulate the function of cell membrane receptors from the perspectives of ligands and receptors in this thesis.The specific research contents are as follows:New functionalized nanomaterials have been developed for customized regulation of cell membrane receptor functions,from the perspectives of ligands and receptors.To address the shortcomings in strategies that use ligands as manipulation objects,in chapter 2,based on the excellent interaction ability of the perfluorinated deoxyribonucleic acid chain（PF-DNA）with proteins,we constructed a PF-DNA/protein nanocomplexes(FD₄₅PN),and verified the feasibility of its cell delivery and responsive release of carrier protein.The experimental results shown that FD₄₅PN synthesized easily,could load proteins efficiently and regulated protein release through the introduction of DNA dynamic elements.In addition,FD₄₅PN could interact with cells and have excellent lysosome escape ability,which is a potential delivery vehicle.In order to explore whether the PF-DNA/protein nanocomplex can regulate the function of cell membrane receptors,in chapter 3,we optimized the length of PF-DNA and selected PF-DNA with a length of 30 nt(PF-DNA₃₀)to construct a cell membrane nanobackpack(PF-DNA₃₀/protein nanocomplexes,FD₃₀PN)which could stably bind to the cell membrane surface.At the same time,a reduction-responsive dynamic control element was introduced to control the release of protein molecules.Then,a cell membrane nanobackpack(PF-DNA₃₀/IL-2 nanocomplexes,FD₃₀P_IN),which can be used to regulate the activity of T cells,was constructed by using IL-2,an immunomodulatory cytokine.The experimental results of in vitro and in vivo shown that FD₃₀P_IN enhanced the survival and immune activity of T cells to a certain extent,which provided a new way for enhancing the effect of adoptive T cell therapy.Considering that the loss of cell membrane receptors is one of the important causes or results of the occurrence and development of many diseases,in Chapter 4,by using DNA and p H（low）insertion peptide（p HLIP）as basic tools,we developed chemically synthesized membrane receptors,termed Ts-p HLIP-Pr,and fully proved its possibility of simulating cell membrane receptor.The experimental results shown that Ts-p HLIP-Pr could anchored on the cell membrane surface efficiently and stably,responded to external p H stimulation and interacted with intracellular target proteins.Considering that the subcellular distribution of protein is one of the important factors for its funct ion,the chemically synthesized membrane receptor is expected to be an effective means to regulate cell behavior and function.We continued to explore the ability of Ts-p HLIP-Pr to simulate the biological function of cell membrane receptors and realize biological regulation in chapter 5.By using biotin as the recruiting molecule of cytoplasmic protein,we constructed Ts-p HLIP-Pr1 and took PKCεfused monomer streptavidin as the research object,to proved the ability of Ts-p HLIP-Pr to regulate PKCε-related biological events.Furthermore,based on the characteristics of the modular design of Ts-p HLIP-Pr,and the interaction between the phosphorylated immunoreceptor tyrosine-activating motif（ITAM）and ZAP70,we extended this strategy to the natural protein ZAP70 system,constructed Ts-p HLIP-Pr2 and realized the effective regulation of T cell activity.Based on the low p H characteristics of the tumor microenvironment,our strategy was expected to provide a new route for engineering intelligent therapeutic cells with customized signaling pathways.