Gold Nanorod Assembly Based Optical Aptasensor for One-Step Detection of Ochratoxin A

摘要

This work describes a novel optical aptasensor based on gold nanorod (GNR) assembly for one-step determination of ochratoxin A (OTA), which is a mycotoxin identified as a contaminant mainly in grains and wine throughout the world. DNA aptamer for OTAexhibiting high affinity and binding specificity has already been used as biorecognition elements to improve the detection performances. Here thiol-modified DNA was decorated on the side sites of GNRs by ligand exchange. The linker DNA containing aptamersequences against OTA hybridized with decorated DNA on the GNRs in the absence of OTA, resulting in side-by-side assembly of GNRs. Otherwise the GNRs dispersed in solution induced by specific aptamer-OTA recognition and conformational changes of aptamerin the presence of OTA. The UV-vis spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used for characterizations. And the induced changes in the optical properties of GNRs could be used for OTA sensing. It was illuminated that a linear correlation existed between the absorbance of GNRs at 708 nm and the concentration of OTA over the range from 0.5 to 20 ng/mL. Moreover the limit of detection (LOD, 3a) obtained was 0.22 ng/mL which could meet the demand for detection of the allowed OTA in agro-products and foods. The developed GNR side-by-side assembly based OTA aptasensor was simple, efficient and cost-effective with only one-step detection. Consequently, it would be a promising tool for toxin screening to guarantee food safety and to minimize the potential risks to human health.