Self-assembled magnetoplasmonic nanochain for DNA sensing

A method is proposed for the subtle control of multifunctional nanoparticles by applying an externalmagnetic field to induce a 1D assembly. Au coated Fe3O4 core-shell nanoparticles (Fe3O4@ Au NPs) wereused to fabricate conducting magnetoplasmonic nanochains (MPNCs). Fe3O4@ Au NPs were synthesizedin an aqueous solution by a one-step reaction, showing superparamagnetic property, and were welldispersed and stable in water at physiological pH. The MPNCs were prepared on a solid substrate throughmagneticfield- induced alignment of Fe3O4@ Au NPs. The dimension of these MPNCs is simply controlledby adjusting magnetic field strength. In order to utilize MPNCs as sensing platform, an annealing step wasperformed to improve their electrical properties. The annealed MPNCs were used as electrical transducersfor DNA detection by successively immobilizing DNA probe on MPNCs and hybridizing them with targetDNA. A direct detection of the electrical changes was performed using linear sweep voltammetry (LSV). A significant resistance increase was observed upon hybridization of the target DNA to the probe DNAon MPNCs. (C) 2014 Elsevier B. V. All rights reserved. As one of the most important spinel-type materials with poten-