Monitoring DNA Immobilization and Hybridization on Surfaces by Atomic Force Microscopy Force Measurements

• Published in: Analytical chemistry (Washington) Vol. 73; no. 10; pp. 2207 - 2212
• Main Authors: Wang, Jian, Bard, Allen J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.05.2001
• Subjects: atomic force microscopy; Base Sequence; Biological and medical sciences; Diverse techniques; DNA - chemistry; Fundamental and applied biological sciences. Psychology; mercaptopropanoic acid; Microscopy, Atomic Force - methods; Molecular and cellular biology; Nucleic Acid Hybridization; ruthenium; Molecular hybridization; Atomic force microscopy; Force measurement; DNA; Immobilization; Aluminium III; Thin film
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac001344a

DNA immobilization and hybridization was carried out on Au substrates that were modified with mercaptopropanoic acid and then treated with aluminum(III) solution. The positively charged Al(III) film can be used to immobilize both ds-DNA and ss-DNA. Atomic force microscopy (AFM) was used to monitor the process by force measurements between a negatively charged silica tip and the substrates while immersed in dilute electrolyte. Surface hybridization of ss-DNA produces an increase in the surface charge and surface potential of the substrates, which is reflected by the increasing repulsive force as determined from AFM force−separation curves. A single-base mismatch was detectable in surface hybridization. The AFM force measuring technique was also employed to investigate the interaction of Ru(phen)3 2+ with ss-DNA and ds-DNA. The force measurement results showed that there is a small interaction between Ru(phen)3 2+ and ss-DNA, which was ascribed to the electrostatic binding of Ru(phen)3 2+ to the ss-DNA surface. For ds-DNA, there is a strong interaction which is believed to be due to the association or intercalation of Ru(phen)3 2+ with ds-DNA.