Imaging of DNA molecules by scanning near-field microscope

• Published in: MATER SCI ENG C BIOMIMETIC SUPRAMOL SYST 2000-08, Vol.12 (1), p.29-32
• Main Authors: Muramatsu, Hiroshi, Homma, Katsunori, Yamamoto, Noritaka, Wang, Jia, Sakata-Sogawa, Kumiko, Shimamoto, Nobuo
• Format: Article
• Language: English
• Subjects: AFM; Atomic force microscopy; Biological and medical sciences; DNA; Fluorescence; Imaging techniques; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Miscellaneous. Technology; Optical fiber; Optical fibers; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Probe; Probes; Scanning; SNOM; YOYO-1
• ISSN: 0928-4931; 1873-0191
• DOI: 10.1016/S0928-4931(00)00153-3

We utilized a novel scanning near-field optical microscope (SNOM) for imaging DNA molecules. The microscope system was constructed with a commercial inverse microscope and a newly developed scanning unit. In the system, a bent optical fiber probe is used to operate in a dynamic mode atomic-force microscope (AFM). A λDNA solution of 5 μM (base) with 5 μM and 500 nM YOYO-1 was prepared and cast on a γ-APTES treated cover slip. The λDNA was aggregated in line and immobilized on the cover slip. The percentage of fluorescence intensity of λDNA with 5 μM YOYO-1 showed integers at almost each point on the DNA. As the fluorescence intensity correlated with the areas of a cross-section of the DNA topography, it appeared that YOYO-1 intercalated in the DNA homogeneously. The fluorescence images of λDNA with 500 nM YOYO-1, however, were irregular and did not correlate with the area of the topographic cross-section, suggesting that YOYO-1 did not intercalate in the λDNA uniformly in this concentration and intercalated cooperatively.