AVS 53rd International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThP

Paper AS-ThP6
Surface Potential Imaging of Self-Organized DNAs acquired by Kelvin Probe Microscopy

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Aspects of Applied Surface Science Poster Session
Presenter: T. Ishizaki, Nagoya University, Japan
Authors: T. Ishizaki, Nagoya University, Japan
N. Saito, Nagoya University, Japan
O. Takai, Nagoya University, Japan
Correspondent: Click to Email
Bioelectronics has been known as a frontier in electronics since biomolecules have attractive functions, which may not be artificially created. Generally, biomoleules work in self-organized units. Novel devices with complex or fuzzy functions would be fabricated when biomolecule is mounted on electronic devices. At first, the basic characteristics of biomolecules on various surfaces must be evaluated toward such technical innovations. There are some reports on the self-organized structures and mechanical properties of biomolecules with atomic force microscopy (AFM) and scanning tunneling microscopy (STM). However, the electric properties have not yet been evaluated by 2-dimensional images, since it is difficult to acquire such images. Kelvin probe force microscope (KPFM) is a powerful tool for measuring microscopic surface potential. In this study, we aim to acquire surface potential images of self-organized DNAs. The DNA sample used in this research was poly(dA-dT)･poly(dA-dT). The DNA was dissolved in ultrapure water (18.2 MΩ) or 0.1 mM MgCl2. The solutions of 10 µl were dropped onto Si(111) substrate, amino-terminated Si(111) substrate or HOPG. The sample solution was allowed to remain on the substrates for 1min and it was then blown off with air. The surface potential images of the samples were acquired by Kelvin probe force microscopy (KPFM). We first observed that the network structure of DNA was formed. The mean height of DNA was 1.2 nm, indicating that the clusters mainly comprised a single layer of DNA molecule. This may be due to an attractive electrostatic force between the substrates and the phosphate group of DNA. The clear surface potential images of self-organized DNA on Si and HOPG were acquired under the condition of an a.c. voltage of 2 V and a frequency of 23 kHz. The surface potential of DNA was c.a. 10 mV higher than that of Si substrate, while it was c.a. 20 mV lower than that of HOPG.