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. 2018 Apr 11;18(4):1161.
doi: 10.3390/s18041161.

Label-Free QCM Immunosensor for the Detection of Ochratoxin A

Şerife Şeyda Pirinçci  1   2 , Özlem Ertekin  3 , Duygu Ercan Laguna  4 , Fehime Şeyma Özen  5 , Zafer Ziya Öztürk  6 , Selma Öztürk  7
Affiliations

Label-Free QCM Immunosensor for the Detection of Ochratoxin A

Şerife Şeyda Pirinçci et al. Sensors (Basel). .

Abstract

Ochratoxin A (OTA) is a potent mycotoxin that poses a risk in food and feed moieties and subject to worldwide regulation. Laboratory-based analytical methods are traditionally employed for reliable OTA quantification, but these methods cannot provide rapid and on-site analysis, where biosensors fill this gap. In this study a label-free quartz crystal microbalance (QCM)-based immunosensor for the detection of OTA, which is one of the most important small molecule contaminants, was developed by direct immobilization of OTA to amine-bearing sensor surfaces using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-Hydroxysuccinimide (NHS) chemistry. The protein-free sensor surface enabled regeneration of sensor surface with 50 mM NaOH and 1% SDS up to 13 times without loss of performance, which would disrupt a protein-containing sensor surface. We developed a QCM immunosensor using the developed sensor surface with a 17.2-200 ng/mL detection range which can be used for on-site detection of feedstuffs.

Keywords: OTA; Ochratoxin A; QCM; immobilization; immunobiosensor; quartz crystal microbalance; regeneration.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic illustration of OTA immobilization to sensor surface. (a) OTA activation with EDC/NHS; and (b) immobilization of activated OTA to SAM coated sensor surface.
Figure 2
Figure 2
Evaluation of different OTA-immobilized surfaces for their antibody binding capacities. In control bar, BSA was sent to the surface and non-specific adsorption of the surface was measured. Error bars represent standard errors.
Figure 3
Figure 3
Regeneration of OTA immobilized sensor surface by using different regeneration solutions. The regeneration solution which provided 100% regeneration efficiency (50 mM NaOH and 1% SDS) was highlighted with the red border.
Figure 4
Figure 4
Regeneration of different OTA-immobilized sensor surfaces with 50 mM NaOH and 1% SDS regeneration solution. Error bars represent standard errors. Each experiment was repeated three times.
Figure 5
Figure 5
Reusability of the OTA-immobilized sensor surface after regeneration by 50 mM NaOH and 1% SDS. Measurements were made by application of 10F4 antibody to sensor surface. Error bars represent standard error. Each experiment was repeated three times.
Figure 6
Figure 6
Selection of optimal antibody concentration for OTA measurement in a competitive assay format.
Figure 7
Figure 7
Sensorgrams showing sensor response at different OTA concentrations: 0.025 mg/mL 10F4 was applied to sensor surface until the sensorgram reaches to saturation, then the surface was washed with PBS.
Figure 8
Figure 8
Dose-response curves for OTA at different measurement time points.
Figure 9
Figure 9
Repeatability of different sensors in terms of percent signal. Error bars represent standard errors.
See this image and copyright information in PMC

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