Studying DNA-Directed Nanoassembly, Hybridization and Mismatch-Discrimination via Plasmon Scattering of Gold Nanoparticles

Abstract

This research study combined the exquisite plasmon scattering properties of spherical gold nanoparticles (nAu) and the specific recognition attributes of DNA to investigate the nAu-DNA assembly formation, and to apply the nanoassemblies for DNA detection. The nanoassembly structures, successfully correlated to the LSPR wavelength shift and the plasmon color change, showed that their homogeneous formations in bulk solution were influenced by parameters inherent to nAu and DNA. The progress of hybridization was monitored through the localized surface plasmon resonance (LSPR) coupling of nAu via dark field microscopy. The particular role of bulky nAu was exploited for distinguishing target DNA having single-base mismatches. Here, a head-to-tail nAu-DNA alignment was found to confer the head- and tail-probe with distinctly different mismatch-discrimination ability. The assay has been extended to perform hybridization on targets bearing non-hybridizing elongated sequences. It was found that these sequences, while reducing the nanoassembly formation efficiency, promoted better discrimination results with relatively lesser impact from the mismatch loci. In order to improve the sensitivity and selectivity, magnetic microparticles (MMP) with superparamagnetism were employed in the LSPR-assisted target DNA detection. The ultrabright non-bleaching plasmonic scattering from nAu allowed direct quantification without the need for additional signal amplification.