PREPARATION OF Ag NANOPARTICLES BASED ON PHOTOIRRADIATION METHOD WITH PLASMID DNA-TEMPLATED

Over the past two decades, interest has been focused on the synthesis of novel nanomaterials with different sizes and different morphologies due to their intriguing chemical, electronic, biosensing, optical and catalytic properties. The biomacromolecules like nucleic acids, proteins, amino acids and peptides have been employed as template for nanomaterial design and synthesis. DNA, which could self-assemble into complex structures such as cubes and squares, is being activley explored for the synthesis of nanomaterials with novel structures and unexpected properties. In this work, the plasmid DNA with 7.5 kB base pairs separated from the bacillus was used as a template to prepare Ag nanoparticles based on the ultraviolet ray (UV) photoirradiation method. The effects of experimental conditions, such as the photoirradiation time and concentration of metallic Ag+ ions, on the composition, morphology, and structure of the obtained nanoparticles were detailed studied. The Ag nanoparticles were characterized by using UV-visible light absorption spectroscopy, TEM and EDS. It is found that Ag+ and UV are necessary in this preparation based on plasmid DNA. The resulted Ag nanoparticles are fcc structure, and the average diameter of obtained nanoparticles is 25-40 nm. The sized of nanoparticles increased with the increasing of the photoirradiation time and the concentration of Ag+. When the mol ratio of Ag+ to base pairs is 4 : 1 and the photoirradiation time is 40 min, the obtained nanoparticles are almost ring-shape with inner diameter of 8-10 nm. In synthesizing process of Ag nanoparticles, only plasmid DNA and Ag+ ions solution were needed, and the plasmid DNA worked not only as template to drive the formation of the Ag nanoparticles, but also as reducer to reduce the Ag+ ions to be metallic Ag. This synthesis method could also be used to prepare other metallic or semiconducting nanoparticles.