Paper NS-TuP4
Effect of Surface Potential on Formation of DNA-Templated Gold Nanowires by pH Change of Gold Nanoparticles

Tuesday, October 16, 2007, 6:00 pm, Room 4C

Biological molecules such as DNA are especially useful as the material for the nanoscale electronic construction because their strand is possible to regulate and their width has nanometer-size diameter of about 2 nm. And also, the negatively charged phosphate group in DNA is possible to bind the surface-functionalized gold nanoparticle (AuNP). However, the location of AuNP with the uniform interval along DNA molecules as template is generally considered to be difficult because precise control of the electrostatic force for conjugation between negatively charged DNA molecules and positively charged AuNPs is hard. In this study, we developed a new method to control the interval between AuNPs on stretched DNA molecules by changing pH of oxidized aniline-capped AuNPs (AN-AuNPs). DNA molecules were stretched and fixed on 3-aminopropyltriethoxysilane (APS) coated Si wafer by the tilting method. Then, pH of AN-AuNPs solution was changed by adding NaOH solution, and DNA molecules were treated with AN-AuNPs solution for the certain time. As NaOH solution was added in AN-AuNPs solution, the surface electric charge of AN-AuNPs was decreased. Atomic force microscopy (AFM) was used to analyze the intervals of AN-AuNPs attached on DNA molecules. The surface electric charge of AN-AuNPs was measured with the change of pH by the Zeta-potential measurement to confirm the interval of AuNPs when the surface electric charge of AN-AuNPs was changed. The effect of AN-AuNPs size on the intervals of AN-AuNPs was also investigated because the AuNPs would be aggregated with the change of pH of AN-AuNPs.