Detection of Ciguatoxins and Tetrodotoxins in Seafood with Biosensors and Other Smart Bioanalytical Systems

Abstract

The emergence of marine toxins such as ciguatoxins (CTXs) and tetrodotoxins (TTXs) in non-endemic regions may pose a serious food safety threat and public health concern if proper control measures are not applied. This article provides an overview of the main biorecognition molecules used for the detection of CTXs and TTXs and the different assay configurations and transduction strategies explored in the development of biosensors and other biotechnological tools for these marine toxins. The advantages and limitations of the systems based on cells, receptors, antibodies, and aptamers are described, and new challenges in marine toxin detection are identified. The validation of these smart bioanalytical systems through analysis of samples and comparison with other techniques is also rationally discussed. These tools have already been demonstrated to be useful in the detection and quantification of CTXs and TTXs, and are, therefore, highly promising for their implementation in research activities and monitoring programs.

Keywords: bioanalytical assays; biosensors; fish; food safety; marine toxins; shellfish.

Figure 1

Schematic representation of the effect of ciguatoxins (CTXs) and tetrodotoxins (TTXs) on the sodium flow dynamics through the membrane of Neuro-2A cells treated with ouabain (O) and veratridine (V).

Figure 2

Schematic representation of a competitive receptor binding assay (RBA) applied to samples with low toxin contents (A) and to samples with high toxin contents (B). The lower the toxin content is in the sample, the more the labeled ligand is bound to the receptor, and the higher the signal is, and vice versa.

Figure 3

Cell-based biosensor (CBB) approaches based on electrophysiology (A–C) and cell viability evaluation (D) for the detection of ciguatoxins (CTXs) and tetrodotoxins (TTXs). Cell-attached patch clamp (A), whole-cell patch clamp (B), microelectrode array (MEA) well (C), and cells immobilized on electrodes (D).

Figure 4

Schematic representation of immunosensors for tetrodotoxins (TTXs) and ciguatoxins (CTXs). The immunosensor for TTXs is based on a competition between the toxin in the sample and the immobilized toxin for binding to the anti-TTX mAb (A). The immunosensor for CTXs is based on a sandwich configuration using two anti-CTX mAbs (B).

Figure 5

Schematic representation of a hybrid sandwich aptamer-based assay for TTXs.