Nucleic Acid Assembly Based On Rolling Circle Amplification Template Modulates The Construction Of Nanoparticles

Due to the unique physical and chemical properties,such as special stability,small size effect,quantum effect,surface effect and special biological affinity effect,Au NPs have always been the focus of research in the field of nanotechnology.At present,there is a great prrrogress in the preparation of gold nanoparticles.The gold nanoparticles with different sizes can be obtained by selecting different types of reducing agents,controlling experimental parameters in the preparation process,and changing the loading order of reafent.As a simple and efficient isothermal enzymatic reaction,the rolling circle amplification(RCA)reaction has been developed as a new technology in the field of nucleic acid amplification.Due to its unique controllable length and easy availability,RCA has a wide range of applications in assembly and multi-functional material preparation.In this paper,we use rolling circle amplification technology as a foundation,and an assembly of Au NPs/DNA was prepared using the characteristics of gold nanoparticles.On this basis,a simple method of structural transformation has been developed,that controlled the conversion of Au NPs/DNA assemblies from linear arrays to nanoring structures only by adjusting the salt concentration of(Na Cl).First,gold nanoparticles with different sizes were prepared by using the seed circulation growth method,and the stability of the gold nanoparticles was examined by the p H and salt tolerance experiments.And the Au NPs were characterized by Uv-vis spectrophotometer(UV-vis),dynamic light scattering(DLS)and transmission electron microscopy(TEM).Second,by investigating the influence of RCA reaction time,d NTPs concentration,primer concentration,and phi29 polymerase concentration on the length of the RCA product,the controllabling of the length of the RCA product was achieved The molecular weight was characterized by agarose gel electrophoresis,and the concentration and purity were characterized by nanodrop.Third,RCA products are used as templates for constructing DNA nanoarrays,which combined with gold nanoparticles are used as structures to construct DNA/Au NPs assemblies.The DNA-Au NPs conjugates were firstly formed by binding the Au NPs with thiol-terminated oligonucleotides,then the conjugates were assembled on DNA nanaoladders to form periodic DNA/Au NPs nanoarrays,which were characterizated by Uv-vis and TEM.Interestingly,the linear DNA/Au NPs array may transformed into nanorings by changing the concentration of Na Cl solution.The structures of the transformation were characterized by UV spectrophotometer,dynamic light scattering,atomic force microscopy(AFM)and TEM.The results showed that high concentration of Na Cl weakened the electrostatic repulsion and lead to the formation of nanoring structures.Four,in order to develop the application of linear DNA/Au NPs nanoarrays,using Au NPs as nanocores on linear DNA/Au NPs nanoarrays,the silver nanowires have been obtained by adddig silver nitrate(Ag NO3).Ag+ was gradually reduced to silver atoms by controlling the amount of reducing agent.The reduced silver atoms were gradually grown on the surface of Au NPs,and these silver nanowires can be used to build biological devices such as biosensors or bio-motors.