Chemiluminescence Switching on Peroxidase-Like Fe3O4 Nanoparticles for Selective Detection and Simultaneous Determination of Various Pesticides

To achieve selectivity in direct chemiluminescence (CL) detection is very significant and a great challenge as well. Here, we report a novel concept of developing intrinsically selective CL switching at the surface of Fe3O4 nanoparticles for the sensitive detection and simultaneous determination of various pesticides. Fe3O4 nanoparticles have peroxidase-like catalytic activity and catalyze the decomposition of dissolved oxygen to generate superoxide anions, so that the CL intensity of luminol was amplified by at least 20 times. The CL signals can be quenched by the addition of ethanol because ethanol readily reacts with superoxide anions as a radical scavenger. However, the quenching effect can be inhibited through the specific binding of target molecules on Fe3O4 nanoparticles, leading to CL turn-on in the presence of ethanol. The novel CL switching on concept demonstrated unique advantages in the detection of pesticide residues. Using the surface coordinative reactions, nonredox pesticide ethoprophos were sensitively detected with a detection limit of 0.1 nM and had a very wide detection range of 0.1 nM to 100 mu M. More importantly, the selectivity of CL switching is tunable through the special surface modification of Fe3O4 nanoparticles, and these Fe3O4 nanoparticles with different surface groups can generate unique CL response pattern for the simultaneous determination of various pesticides Meanwhile, the superparamagnetic properties of Fe3O4 nanoparticles provide a simple magnetic separation approach to attain interference free measurement for real detection. The very facile and versatile strategy reported here should open a new window to exploration of selective CL molecular switching and application of magnetic nanoparticles for chemo/biodetection.