Formation and Nanomechanical Properties of Silver-Mediated Guanine DNA Duplexes in Aqueous Solution
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- Department of Materials Science and Engineering, University of California, Irvine, California 92697, United States
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Irvine, California 92697, United States, Department of Physics and Astronomy, University of California, Irvine, California 92697, United States, Department of Chemical and Biomolecular Engineering, University of California, Irvine, California 92697, United States
Silver cations can mediate base pairing of guanine (G) DNA oligomers, yielding linear parallel G–Ag+–G duplexes with enhanced stabilities compared to those of canonical DNA duplexes. To enable their use in programmable DNA nanotechnologies, it is critical to understand solution-state formation and the nanomechanical stiffness of G–Ag+–G duplexes. Using temperature-controlled circular dichroism (CD) spectroscopy, we find that heating mixtures of G oligomers and silver salt above 50 °C fully destabilizes G-quadruplex structures and converts oligomers to G–Ag+–G duplexes. Electrospray ionization mass spectrometry supports that G–Ag+–G duplexes form at stoichiometries of 1 Ag+ per base pair, and CD spectroscopy suggests that as the Ag+/base stoichiometry increases further, G–Ag+–G duplexes undergo additional morphological changes. Using liquidphase atomic force microscopy, we find that this excess Ag+ enables assembly of long fiberlike structures with ~2.5 nm heights equivalent to a single DNA duplex but with lengths that far exceed a single duplex. Finally, using the conditions established to form single G–Ag+–G duplexes, we use a surface forces apparatus (SFA) to compare the solution-phase stiffness of single G– Ag+–G duplexes with dG-dC Watson–Crick–Franklin duplexes. SFA shows that G–Ag+–G duplexes are 1.3 times stiffer than dG-dC duplexes, confirming gas-phase ion mobility spectrometry measurements and computational predictions. These findings may guide the development of structural DNA nanotechnologies that rely on silver-mediated base pairing.
- Research Organization:
- Univ. of California, Irvine, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 2281457
- Alternate ID(s):
- OSTI ID: 2283301
- Journal Information:
- ACS Nano, Journal Name: ACS Nano Vol. 18 Journal Issue: 4; ISSN 1936-0851
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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