Highly sensitive and selective detection of Ochratoxin a using modified graphene oxide-aptamer sensors as well as application

Abstract

Graphene oxide (GO) and specific aptamer were used to assay Ochratoxin A (OTA) in this work. Briefly, GO played a role in quenching the fluorescent group of specific aptamer in the absence of OTA. However, the fluorescence restoration could be observed in the presence of OTA based on the sensing platform. Therefore, through utilizing bare GO and optimizing the detective conditions, the detection limit of this unmodified biosensor was preliminarily obtained to be 886.7 nM with a linear detection range from 1 μM to 20 μM. Above all, to avoid the nonspecific adsorption of OTA on the surface of GO and improve the sensitivity of the sensor, surface blockers (Tween 20, CTAB, and oligonucleotides) were used to modify GO in this investigation. And Tween 20 was finally selected as the suitable surface blocker by comparing their experimental data. Based on this fact, the Tween 20 modified sensing platform reveals a lower detection limit to 3.12 nM, and shows a strong linear relationship within the detection range from 5 nM to 200 nM (R2 = 0.997). Results of this study also demonstrated that the detecting platform exhibited excellent selectivity for OTA against other fungi toxins. In addition, this purposed assay was challenged by testing food samples that contained buffer solution spiked with different concentrations of OTA. These results indicate that this method has a promising analytical application in food detection.