[Preparation of DNA silver nanowire and its Raman spectra]

Silver nanoparticles were synthesized by the method of combining heating with UV irradiation. In the authors' work, the shape and size of nanograins which carry positive electrical charges are uniform and their average diameter is 7.8 nm. Based on the electrostatic self-assembly characteristics of DNA, silver nanoparticles were equally assembled on predefined aligned calf thymus DNA to form DNA silver nanowires. The diameter of the wires is about 30 nm and the length is 2 microm. The Raman spectra indicate that the silver nanoparticles mainly attach to the backbone chain of DNA and affect the vibration properties of deoxyribose and base. The intensity of the peaks at 782 and 1 098 cm(-1) assigned to stretch vibration of phosphoric skeleton decreases sharply and the band at 782 cm(-1) shifts to 791 cm(-1). The bands of deoxyribose C-O stretch vibration at 1 011 and 1 050 cm(-1) shift to 1 030 and 1 064 cm(-1) respectively. The characteristic peaks of bases at 1 372, 1 334, 1 304 and 728 cm(-1) shift to 1 368, 1 320, 1 294 and 731 cm(-1), respectively.