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Instantaneous and Quantitative Functionalization of Gold Nanoparticles with Thiolated DNA Using a pH-Assisted and Surfactant-Free Route
journal contribution
posted on 2012-05-02, 00:00 authored by Xu Zhang, Mark R. Servos, Juewen LiuThe attachment of thiolated DNA to gold nanoparticles
(AuNPs) has
enabled many landmark works in nanobiotechnology. This conjugate chemistry
is typically performed using a salt-aging protocol where, in the presence
of an excess amount of DNA, NaCl is gradually added to increase DNA
loading over 1–2 days. To functionalize large AuNPs, surfactants
need to be used, which may generate difficulties for downstream biological
applications. We report herein a novel method using a pH 3.0 citrate
buffer to complete the attachment process in a few minutes. More importantly,
it allows for quantitative DNA adsorption, eliminating the need to
quantify the number of adsorbed DNA and allowing the adsorption of
multiple DNAs with different sequences at predetermined ratios. The
method has been tested for various DNAs over a wide range of AuNP
sizes. Our work suggests a synergistic effect between pH and salt
in DNA attachment and reveals the fundamental kinetics of AuNP aggregation
versus DNA adsorption, providing a novel means to modulate the interactions
between DNA and AuNPs.