Design of a Quencher-Free Fluorescent Aptasensor for Ochratoxin A Detection in Red Wine Based on the Guanine-Quenching Ability

Abstract

This study describes a quencher-free fluorescent aptasensor for ochratoxin A (OTA) detection using the specific quenching ability of guanine for fluorescein (FAM) molecules based on photo-induced electron transfer (PIET). In this strategy, OTA is detected by monitoring the fluorescence change induced by the conformational change of the aptamer after target binding. A new shorter OTA aptamer compromising three guanine bases at the 5′ end was used in this study. This new aptamer, named G3-OTAapt1-FAM (F1), was labeled with FAM on the 3′ end as a fluorophore. In order to increase the binding affinity of the aptamer and OTA, G3-OTAapt2-FAM (F2) was designed; this added a pair of complementary bases at the end compared with F1. To prevent the strong self-quenching of F2, a complementary chain, A13, was added. Although the F1 aptasensor was simpler to implement, the sensitivity of the F2 aptasensor with A13 was better than that of F1. The proposed F1 and F2 sensors can detect OTA with a concentration as low as 0.69 nmol/L and 0.36 nmol/L, respectively.

Multifunctional Smart ZnSe-Nanostructure-Based Fluorescent Aptasensor for the Detection of Ochratoxin A

“…As shown in Figure 6 a, the pure dye solution (160 ng/L) presented a strong fluorescence maximum at 578 nm. On adding a ZnSe-B6 nanoquencher, an appreciable decrease in fluorescence response was found ( Figure 6 b), which is primarily can be attributed to Förster resonance energy transfer (FRET), based on the strong binding interaction between cationic Rh-B dye and the highly negatively charged surface of ZnSe-B6 [ 32 , 33 ]. To develop the ZnSe-B6-based aptasensor, already optimized concentration, sonication time and incubation time values for the ZnSe-B6 were used.…”

“…The quenching response of type ZnSe-B6 on the emission spectrum of Rh-B dye in the presence of an OTA aptamer was evaluated with and without an OTA target. Pure Rh-B exhibited a sharp fluorescence peak, which significantly reduced after the addition of ZnSe-B6 nanoquencher, which primarily can be attributed to an FRET mechanism based on the strong binding interaction between cationic Rh-B dye and the highly negatively charged surface of ZnSe-B6 [ 32 , 33 ]. Scheme 1 B shows step by step details of the fabrication of a ZnSe-nanostructure-based fluorescent aptasensor for the detection of OTA.…”

Current Review of Mycotoxin Biodegradation and Bioadsorption: Microorganisms, Mechanisms, and Main Important Applications

“…OTA production in grapes and grape-derived products is a severe problem in the wine production field, especially in European countries where the climate conditions favor the growth of ochratoxigenic Aspergillus species. Thus, since March 2002, maximum OTA levels in cereals and dried vine fruits are regulated by the EU [55,56].…”