Title: Base dependent adsorption of single-stranded homo-oligonucleotides to gold nanoparticles

Authors: Omar A. Alsager; Sarah K. Andreassend; Bicheng Zhu; Jadranka Travas-Sejdic; Justin M. Hodgkiss

Addresses: The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand; School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, 6040, New Zealand; King Abdulaziz City for Science and Technology, Riyadh, 11442, Saudi Arabia ' School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, 6040, New Zealand ' The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand; Polymer Electronics Research Centre, School of Chemical Sciences, University of Auckland, Auckland, 1010, New Zealand ' The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand; Polymer Electronics Research Centre, School of Chemical Sciences, University of Auckland, Auckland, 1010, New Zealand ' The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand; School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, 6040, New Zealand

Abstract: Many bioanalytical devices now feature DNA immobilised on optically or electrically addressed gold surfaces, either via covalent (thiol) tethers, or non-specifically adsorbed via the DNA nucleobases. To guide the development of colorimetric biosensors that depend on the dissociation of adsorbed DNA aptamers, the interaction of homo-30-mers composed of each of the bases with gold nanoparticles was investigated. Through colorimetric measurements of the stability of DNA-coated gold nanoparticle dispersions, stability was found to decrease in the order A > T > C ≥ G, counter to expectations based on intrinsic affinities. These observations were reconciled using electrochemical measurements of DNA surface densities on gold nanoparticle electrodes; while the measured surface densities correlated with the dispersion stabilities, it was apparent that many bases of a long DNA strand were dangling from the surface, rather than directly adsorbed. Thus, even (dT)₃₀, whose bases have the weakest affinity to gold, can cover a gold surface with high total density since many of the bases will simply be tethered, and still contributing to the stability of a nanoparticle dispersion.

Keywords: oligonucleotides; DNA surface densities; gold nanoparticles; colorimetric biosensors; aptasensors; nanotechnology; base dependent adsorption; nanoparticle dispersion.

DOI: 10.1504/IJNT.2017.082474

International Journal of Nanotechnology, 2017 Vol.14 No.1/2/3/4/5/6, pp.519 - 529

Published online: 24 Feb 2017 *

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