Impedimetric Aptasensor for Ochratoxin A Determination Based on Au Nanoparticles Stabilized with Hyper-Branched Polymer

Abstract

An impedimetric aptasensor for ochratoxin A (OTA) detection has been developed on the base of a gold electrode covered with a new modifier consisting of electropolymerized Neutral Red and a mixture of Au nanoparticles suspended in the dendrimeric polymer Botlorn H30®. Thiolated aptamer specific to OTA was covalently attached to Au nanoparticles via Au-S bonding. The interaction of the aptamer with OTA induced the conformational switch of the aptamer from linear to guanine quadruplex form followed by consolidation of the surface layer and an increase of the charge transfer resistance. The aptasensor makes it possible to detect from 0.1 to 100 nM of OTA (limit of detection: 0.02 nM) in the presence of at least 50 fold excess of ochratoxin B. The applicability of the aptasensor for real sample assay was confirmed by testing spiked beer samples. The recovery of 2 nM OTA was found to be 70% for light beer and 78% for dark beer.

Thermolysin entrapped in a gold nanoparticles/polymer composite for direct and sensitive conductometric biosensing of ochratoxin A in olive oil

“…The conductometric response was linear up to 60 nM for the AuNPs/PVA/PEI biosensor and up to 75 M for the TLN/BSA biosensor. A large number of electrochemical biosensors have been [18] already reported for OTA detection, most of them relying on the affinity of the molecule for specific antibodies or aptamers [18][19][55][56][57][58][59][60][61][62][63][64][65][66]. As seen in Table 1, aptasensors recently proposed in the literature are far more sensitive than any other type of biosensor ever proposed.…”

Sensors Based on Bio and Biomimetic Receptors in Medical Diagnostic, Environment, and Food Analysis

“…The detection limit of the sensor is 14 ng/mL and its linear range is 20–160 ng/mL. A label-free impedimetric aptasensor for ochratoxin A detection based on immobilized thiol-modified aptamers on Ag nanoparticles, which were decorated on the gold surface, is proposed in [ 325 ]. The analytical signal is detected in the presence of a ferricyanide redox mediator.…”

Food Safety Analysis Using Electrochemical Biosensors

“…Various strategies have been proposed for signal enhancement using AuNPs, MNPs, and graphene derivatives. An additional approach combining AuNPs and polymers for an efficient detection of OTA was reported by Etvugyn et al [ 69 ]. In this work, an impedimetric aptasensor was prepared by drop casting a suspension of Au NPs stabilized by the dendrimeric polymer Botlorn H30 ® (Perstorp Speciality Chemicals AB, Perstorp Sweden) onto gold electrodes previously modified by electropolymerized Neutral Red.…”