The operation principle and configuration of the Scanning Near-field Optical/Atomic Force Microscope (SNOAM) is introduced in the paper. DNA molecules were imaged in AFM mode and in SNOM mode. The topography images and the fluorescence images of single DNA molecule were obtained. The topography image in SNOM mode is of high resolution. The near-field fluorescence image shows the fluorescence distribution of DNA molecules. (lambda) DNA Molecules, in which YOYO-1 was intercalated, were imaged and characterized. For (lambda) DNA with 5 (mu) M YOYO-1, there is variation in the fluorescence intensity of the DNA and ratios of the fluorescence intensity showed almost integers in each region. As the fluorescence intensity correlated with the area of cross section in the DNA topography, it was suggested that YOYO-1 intercalated in the DNA homogeneously. Contrary, the fluorescence intensity of (lambda) DNA with 500 (mu) M YOYO-1 was heterogeneous and did not correlate with the area of topographic cross section. This suggested that YOYO-1 was not intercalated to (lambda) DNA uniformly in the concentration and intercalated partially and cooperatively.

Date Published: 3 October 2000
PDF: 5 pages
Proc. SPIE 4220, Advanced Photonic Sensors: Technology and Applications, (3 October 2000); doi: 10.1117/12.401695

Published in SPIE Proceedings Vol. 4220:
Advanced Photonic Sensors: Technology and Applications
Jinfa Tang; Chao-Nan Xu; Haizhang Li, Editor(s)