Constrution Of Double Rolling Circle Amplication DNA Network For Stem Cells Capture

As a biofunctional polymer,DNA has aroused extensive attention because of its molecular recognition capability,sequence programmability and biocompatibility.In recent years,DNA has been further applied in cell engineering,such as cell capture,3D cell culture and tissue engineering,which has opened a new way for biomedical field.This thesis focuses on the synthesis,properties and biological applications of double rolling circle amplification(RCA)DNA network,and investigates the double RCA DNA network for efficient and specific capture,moreover the enzyme-triggered cell release.The main research contents are summarized as follows:In the first chapter,the features of stem cells and development of stem cells capture were overviewed.Besides,we comprehensively introduced the biomaterials for cell capture,and further introduced the strategy of DNA network crosslink.Furthermore we elaborated the application of DNA network in cell engineering.In the second chapter,a double RCA DNA network was designed and synthesized.Firstly,circular DNA-1 and circular DNA-2 were synthesized.Then DNA chain-1 is prepared to specifically capture BMSC and DNA chain-2 is prepared to hybridize with DNA chain-1 by RCA.DNA chain-1 and DNA chain-2 formed the3 D network through hybridization and physical cross-link.The photos of fluorescence microscope and scanning electron microscopets showed that the DNA network had fibrous network structure and low mechanical properties.In addition,the DNA network has good biocompatibility and injectability.These advantages are a favorable basis for capturing cells.In the third chapter,BMSCs were efficiently captured by DNA network synthesized in chapter 2.Cell membrane colocalization experiments demonstrated the specific anchoring of aptamers and cell membrane.BMSCs were specifically captured with DNA networks containing aptamers,and the BMSCs showed three dimensions spatial distribution in the DNA network.Furthermore,the effects of capture time,cell numbers,DNA network volume,the length of DNA chain,relative size of circular template and other factors on the efficiency of BMSCs capture were studied.Later,BMSCs were captured from mixed cells and bone marrow using DNA network,which proved that this DNA network could efficiently and specifically capture BMSCs.In the fourth chapter,by the catalysis of DNase I,BMSCs captured by DNA network were released controllably.By adjusting the concentration of DNase I,the degradation rate of DNA network can be controlled,and the cells can be released controllably over time.The released BMSCs not only showed normal morphology,but also maintained high viability and pluripotency.In the last chapter,we summarize and forecast this paper.The double RCA DNA network synthesized in this study can capture BMSCs efficiently,which provides new ideas for cell engineering.At the same time,the design of the DNA network provides a general strategy for capturing other types of cells.