A label-free aptasensor for turn-on fluorescent detection of ochratoxin a based on SYBR gold and single walled carbon nanohorns

Ochratoxin A (OTA), is one of the most commonly found mycotoxins in food. It is primarily produced by Aspergillus ochraceus and Penicillium verrucosum. OTA can causes serious damages to liver and kidney, increases the teratogenicity, and has been considered as a potential carcinogen (group 2 B). In this study, we demonstrated a new detection system for the detection of OTA using fluorescence biosensing according to an anti-OTA aptamer and fluorescence quencher using single-walled carbon nanohorns (SWCNHs). In the presence of OTA, the OTA-specific aptamer underwent the conformation change from a random coil to an antiparallel G-quadruplex. The latter one was resistant to being adsorbed onto SWCNHs, leading to the pertection of the fluorescence of SYBR Gold. As a result, the remained fluorescent intensities correlated with the concentrations of OTA. The detection limit of OTA was 2.3 ng/ml, meanwhile the linear detection range was 5-500 ng/ml, with a satisfactory linear correlation (R-2 = 0.992) of the fluorescence intensity and the logarithm of OTA concentrations. The aptasensor was subjected to quantify the concentration of OTA in red wine samples. As a result, this label-free aptasensor was suitable for the test of OTA in food samples.

Automated summary

This study demonstrated a new detection system for OTA using fluorescence biosensing based on an anti-OTA aptamer and fluorescence quencher, using single-walled carbon nanohorns. The detection limit of OTA was 2.3 ng/ml with a linear detection range of 5-500 ng/ml. The aptasensor was found suitable for the quantification of OTA in food samples.