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Updated: Feb 14, 2026

Gold Nanoparticle Synthesis
Published on: July 10, 2021
Spectroscopic and Hydrodynamic Characterisation of DNA-Linked Gold Nanoparticle Dimers in Solution using Two-Photon
Johanna Midelet1, Afaf H El-Sagheer2, Tom Brown2
1Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, United Kingdom.
Abstract:
Two-photon photoluminescence (TPPL) emission spectra of DNA-gold nanoparticle (AuNP) monoconjugates and the corresponding DNA-linked AuNP dimers are obtained by photon time-of-flight spectroscopy. This technique is combined with two-photon photoluminescence fluctuation correlation spectroscopy (TPPL-FCS) to simultaneously monitor the optical and hydrodynamic behaviour of these nano-assemblies in solution, with single-particle sensitivity and microsecond temporal resolution. In this study, the AuNPs have an average core diameter of 12 nm, which renders their dark-field plasmonic light scattering too weak for single-particle imaging. Moreover, as a result of the lack of plasmonic coupling in the dimers, the optical extinction, scattering and photoluminescence spectra of the DNA-AuNP complexes are not sufficiently different to distinguish between monomers and dimers. The use of TPPL-FCS successfully addresses these bottlenecks and enables the distinction between AuNP monomers and AuNP dimers in solution by measurement of their hydrodynamic rotational and translational diffusion.
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