Research Of DNA Nano-ring And Its Metallization

Micromachining technology has increasingly become a new trend in the field ofmaterials science. Patterned nanomaterials are the centre of the micromachiningtechnology. Nowadays, due to the limitations of top-down approach, the processing formicromachining is gradually replaced by bottom-up approach. Lately, the processtechnology of bottom-up based on the template has become the hot spot. DNA is widelyrecognized as an ideal template for the synthesis of Ag NPs thanks to the uniquestability, Easy Graphical Access and association with Ag+. Moreover, functionalnanomaterials based on DNA template assembly are also a growing field in recent years.As common functional nanomaterials, fluorescent nanoparticles provide a kind of newmaterial for fluorescence imaging and have broad application prospects in theBiomedical Sciences.Firstly, we designed a polyacrylamide gel electrophoresis based on horizontalelectrophoresis for the characterization of DNA. By adding the organic glasses andgalss slides on the gel tray, we can adjust the thickness of the gel and isolate oxygen.The apparatus allows a simple and rapid preparation of horizontal polyacrylamide gelsfor different purposes. Preparation of such gels is as easy and rapid as agarose gelpreparation, and polymerized polyacrylamide gels are used to fractionate proteins orsmall DNA fragments using a common horizontal electrophoretic tank. Furthermore, weoptimized the gel thickness and the electrophoresis voltage according to therequirements of subsequent experiments. Experimental results show that the gel of2mm and voltage of60V are the optimal conditions for the electrophoresis.Secondly, this paper reports on synthesis the strong fluorescence of small silvernanoparticles (Ag NPs) induced by circular single strand DNA (ssDNA). The great UVabsorption of the circular ssDNA and the synthetic process of the Ag NPs on bothcircular ssDNA and linear ssDNA were determined by measuring its UV–Vis spectra.Transmission electron microscopy (TEM) exhibited circular ssDNA-stabilized Ag NPspossessed smaller size that may contribute to the stronger fluorescence compared withlinear ssDNA. Fluorescence spectra revealed that the fluorescence intensity of thecircular ssDNA-Ag NPs showed4.5times stronger than that of the linear ssDNA-AgNPs. In addition, excitation wavelengths caused by both the circular ssDNA and thelinear ssDNA are located in270nm which is the same as the maximum absorbance of ssDNA. This phenomenon shows that energy transfer from the DNA bases to Ag NPsmay be the possible mechanism. Therefore, the greater UV utilization efficiency ofcircular ssDNA may be the other reason for higher emission of the circular ssDNA-AgNPs.Finally, we also describe the metallization of the circular double strand DNA (dsDNA). The integration of Ag NPs and DNA was measured by CD spectra. UV-visspectra showed that the circular dsDNA-Ag NPs own a stronger surface plasmonresonance peak of Ag NPs. TEM exhibited that the metallization caused by the templateof the circular dsDNA trended to synthesize Ag nanorings composed of threenanoparticles with average diameter of about17.1nm. The excellent agreementbetween the diameter of the circular dsDNA and the diameter of the ring formed by thecentre of the three nanoparticles revealed that the adsorption of Ag+on the circularssDNA can form three active sites and nanoparticles are synthesized at the three activesites.In this paper, we put forward the metallization of both the circular ssDNA and thecircular dsDNA, and prepared the fluorescent Ag NPs and the Ag nanoring. Bycomparing with the linear DNA, nanomaterials possessed excellent property. There arewidely development prospects in both micromachining and biomedical fluorescenceimaging.