What Controls the Melting Properties of DNA-Linked Gold Nanoparticle Assemblies?

Abstract

We report a series of experiments and a theoretical model designed to systematically define and evaluate the relative importance of nanoparticle, oligonucleotide, and environmental variables that contribute to the observed sharp melting transitions associated with DNA-linked nanoparticle structures. These variables include the size of the nanoparticles, the surface density of the oligonucleotides on the nanoparticles, the dielectric constant of the surrounding medium, target concentration, and the position of the nanoparticles with respect to one another within the aggregate. The experimental data may be understood in terms of a thermodynamic model that attributes the sharp melting to a cooperative mechanism that results from two key factors: the presence of multiple DNA linkers between each pair of nanoparticles and a decrease in the melting temperature as DNA strands melt due to a concomitant reduction in local salt concentration. The cooperative melting effect, originating from short-range duplex-to-duplex interactions, is independent of DNA base sequences studied and should be universal for any type of nanostructured probe that is heavily functionalized with oligonucleotides. Understanding the fundamental origins of the melting properties of DNA-linked nanoparticle aggregates (or monolayers) is of paramount importance because these properties directly impact one's ability to formulate high sensitivity and selectivity DNA detection systems and construct materials from these novel nanoparticle materials.

Particle-by-Particle Charge Analysis of DNA-Modified Nanoparticles Using Tunable Resistive Pulse Sensing

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Submicrometer Cavity Surface Plasmon Sensors

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DNA-Functionalized Gold Nanoparticles in Macromolecularly Crowded Polymer Solutions

“…21,28 This adsorption may increase the difficulty to push the PEG out of the where co-operative melting of the multiple DNA linkages has been proposed to be responsible for such sharp melting transitions. [30][31][32] In our current system, DNA-capped AuNPs also aggregated in PEG even without linker DNA and we wonder if the sharp transition is still maintained. For this purpose, heated DNA-capped AuNPs were gradually heated in 10% PEG 8k or 20k samples with 0.5 M NaCl.…”