A performance evaluation of Fe3O4/Au and gamma-Fe2O3/Au core/shell magnetic nanoparticles in an electrochemical DNA bioassay

Abstract

The present study aimed at synthesizing and evaluating Fe3O4/Au and gamma-Fe3O4/Au core/shell magnetic nanoparticles (MNPs) in an electrochemical DNA bioassay to achieve favorable nanostructure for biosensing applications. Firstly, the MNPs were synthesized using co-precipitation method for synthesis of iron oxide cores followed by citrate reduction of Au precursor to form Au shell. Then, the structural analysis of these two MNPs by UV Vis spectroscopy, XRD, FE-SEM, EDS, TEM and cyclic voltammetry confirmed their core/shell structures. The results revealed that, compared to Fe3O4/Au, a thicker, Au shell was formed on gamma-Fe3O4/Au. Moreover, the VSM analysis showed the superparamagnetic nature of the both MNPs with considerable reduction in magnetic property for gamma-Fe3O4/Au compared to Fe3O4/Au. Finally, the synthesized MNPs were employed in an electrochemical DNA bioassay, consisting of surface modification of MNPs, hybridization by target and reporter probe, and magnetic field assisted separation steps. The results exhibit that Fe3O4/Au has better performance than gamma-Fe3O4/Au in detection of target oligonucleotide. (C) 2017 Elsevier B.V. All rights reserved.