| Benefited from their high precision programmability,addressable ability,good biocompatibility,and easy site-specific modification,DNA molecules have been widely studied in the construction of specific structural materials,biosensing,drug delivery,cell imaging and cell behavior regulation.However,as a kind of important biological material,DNA still faces challenges in the study of cell membrane surface functionalization,such as:(1)the cell membrane is a highly dynamic and complex environment,resulting in that the small size of DNA molecules is inserted into the membrane in a way of low efficiency and poor stability,and are easy to fall off or to be internalized;(2)The use of DNA nanostructures to regulate the interaction between cells is relatively simple,and it is necessary to develop a variety of regulation methods for recognition and binding between cells.Aiming at the above problems,this thesis uses DNA triangular prisms and DNA branched polymers as structural motifs to construct DNA network structures and use them for the regulation of cell-cell interactions.We first used rolling circle reaction(RCA)to prepare micron-scale DNA linear structures,which facilitated the hydrophobic interaction between cholesterol and phospholipid membranes,thereby anchoring cholesterol-modified DNA nanowires on the cell membrane surface.Subsequently,we constructed DNA network structures using DNA triangular prisms and DNA branched polymers as structural motifs and used them to regulate cell-tocell recognition and aggregation.Finally,we constructed DNA nanowires based on nucleic acid aptamers,using the interaction of nucleic acid aptamers with target proteins on the cell membrane surface to achieve efficient regulation of cell-to-cell recognition and aggregation.(1)In Chapter 2,we prepared micron-scale DNA linear structures by Rolling Circle Amplification(RCA)and anchored them to the cell membrane surface.By optimizing the reaction time of RCA and the post-treatment conditions(temperature,salt concentration),micron-scale DNA linear products could be obtained.Cholesterolmodified DNA linear structures could be stably anchored on the cell membrane surface,providing a research basis for large-scale DNA linear structures to be used for cell membrane surface modification.(2)In Chapter 3,we constructed a variety of DNA network structures with DNA triangular prisms and DNA branched polymers as structural motifs and anchored them on the cell membrane surface.The structure of the DNA network on the surface of the cell membrane could be easily regulated by regulating the proportion and order of the DNA trigonal prism and DNA branched polymer structures in the DNA network structure.The experimental results showed that this DNA network structure could be stably anchored on the cell membrane surface and had good biocompatibility,laying a foundation for the subsequent use of DNA network structure to regulate cell-cell interactions.(3)In Chapter 4,we use DNA network structure to regulate recognition and aggregation between cells.Based on the principle of DNA base complementation,we use the DNA network structure to achieve non-specific intercellular recognition and aggregation;by introducing functional nucleic acids,we use the DNA network structure to achieve stimuli-responsive intercellular recognition and aggregation;through the comprehensive application of the above means to achieve reversible regulation of cell-to-cell aggregation.In addition,we blocked cell-to-cell interactions by shielding cell-surface recognition components using a multilayer DNA network structure.Finally,we preliminarily verified that the DNA network structure can regulate the binding between cells and the transport of substances between cells.(4)In Chapter 5,we construct aptamer-based DNA nanowires for regulating cellto-cell recognition and aggregation.We first constructed DNA nanowires with adjustable length,and obtained aptamer nanowires with multivalent recognition by introducing aptamers.The experimental results show that the binding between the aptamer nanowire and the target cell depends on the type and quantity of the target protein on the cell surface and the type and quantity of the aptamer in the aptamer nanowire.The method of aptamer based DNA nanowire for regulating cell-to-cell recognition and aggregation has the advantages of good specificity and strong binding force.In brief,the DNA network structure constructed in this paper has good stability,biocompatibility and excellent controllability,and has potential application value in the regulation of cell function and cell behavior. |
