A novel electrochemical immunosensor for ochratoxin A with hapten immobilization on thionine/gold nanoparticle modified glassy carbon electrode

Abstract

A novel electrochemical sensor was developed based on the combination of polythionine (PTH)/gold nanoparticle (nanoAu) composite film and enzyme catalysis amplification for the indirect competitive immunoassay of ochratoxin A (OTA). The sensing substrate was fabricated using a glassy carbon electrode (GCE) modified with an electropolymerized film of polythionine, which then mediated the self-assembly of nanoAu monolayer. After OTA-ovalbumin conjugates (OTA-OVA) were adsorbed onto the surface-confined gold nanoparticles, the analyte OTA in sample solution competed for the limited anti-OTA monoclonal antibodies with the immobilized hapten. Alkaline phosphatase (ALP)-labeled horse anti-mouse IgG antibodies were selectively bound onto the surface of the electrode, which afforded an indicator for OTA concentration in the sample. Under the optimal conditions, electrochemical response arising from the oxidation of enzymatic product of 1-naphthyl phosphate was observed to be inversely proportional to OTA concentration in the range from 1 ng mL À1 to 1000 ng mL À1 with a detection limit as low as 0.2 ng mL À1 . In addition, good reproducibility, high selectivity, sensitivity and stability were achieved. The recovery test demonstrated the feasibility of the proposed method for accurate determination of OTA contaminated samples.

Electrochemical Aptasensor for the Determination of Ochratoxin A at the Au Electrode Modified with Ag Nanoparticles Decorated with Macrocyclic Ligand

“…Direct oxidation of OTA from alkaline solution at glassy carbon electrode was evaluated by measurement of the current using square‐wave voltammetry 17. Electrochemical immunosensors for OTA detection have been developed on the base of mono‐ and polyclonal antibodies attached to Au nanoparticles 18–21, magnetic beads 22, 23 and ZnO 24 nanostructures. The signal was measured using cyclic voltammetry and electrochemical impedance spectroscopy (EIS).…”

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.…”

An Overview of Recent Electrochemical Immunosensing Strategies for Mycotoxins Detection

“…An enzyme‐labeled indirect competitive immunosensor was constructed by modifying GCE surface with an electropolymerized film of polythionine, which then mediated the self‐assembly of nano Au monolayer to immobilize OTA. The device showed good reproducibility, high selectivity, sensitivity and stability .…”