Abstract:
Okadaic acid (OA) is one of the known marine biotoxins produced by various dinoflagellates and exists
in seafood such as shellfish. The consumption of contaminated shellfish with OA leads to diarrheic
shellfish poisoning (DSP), which results in the inhibition of protein phosphatase enzymes in humans. This
poisoning can cause immunotoxicity and tumor promotion due to the accumulation of okadaic acid in
more than the allowed limit in bivalve molluscs. The reported methods for the detection of okadaic acid
include mouse bioassays, immunoassays, chromatography coupled with spectroscopic techniques, electrochemical
sensors and immunosensors. We have developed a naphthalimide-gold-based nanocomposite
for the detection of okadaic acid. Individually, the organic nanoparticles (ONPs) of synthesized
naphthalimide-based receptors and gold-coated ONPs are less sensitive for detection. However,
fabrication of the composite of Au@ONPs and ONPs enhance the sensing properties and selectivity. The
composite shows a ratiometric response in the UV-Vis absorption spectrum and quenching in the
fluorescence profile with a detection limit of 20 nM for OA in aqueous medium. In cyclic voltammetry, a
shift was observed in the cathodic peak ( 0.532 V to 0.618 V) as well as in the anodic peak ( 0.815 V
to 0.847 V) with the addition of okadaic acid. To study the quick binding of the composite with OA, a
time response experiment was performed. Also, the developed sensor retains its sensing ability in the pH
range of 5–9 and in high salt conditions. Our developed composite can be used for the detection of OA
in real applications.
