A new nano biosensor for maitotoxin with high sensitivity and selectivity based fluorescence resonance energy transfer between carbon quantum dots and gold nanoparticles

Maitotoxin (MTX) is a potent marine toxin with critical LD50, which usually causes poisoning because of eating the contaminated marine crustaceans. This poison is a severe threat to neuronal systems and also disables the heart by increasing the calcium ions flow in the cardiovascular. Therefore, the quantitative determination of MTX by using a fast and cost-effective way is essential. Application of carbon dots in the structure of various sensors for the measurement of biological compounds has been developed due to its easy, rapid and inexpensive synthesis. In this study, carbon quantum dots (CQDs) and gold nanoparticles (AuNPs) were synthesized for the determination of MTX with high sensitivity and selectivity. The structure of CQDs and AuNPs were characterized using SEM (Scanning electron microscopy), TEM (Transmission electron microscopy), EDS (Energy-dispersive X-ray spectroscopy) and FT-IR (Fourier-transform infrared spectroscopy) techniques. The Basis of the sensing method is fluorescence resonance energy transfer (FRET) which occurs between energy donor (CQDs) and energy acceptor (AuNPs). Under optimal conditions (excitation wavelength 430 nm and emission wavelength 523 nm), the linear range and detection limit were obtained 1 -600 pmol L-1 and 0.3 pmol L-1, respectively. The strong point of this nanosensor is its very fast quenching process. The interference effect of other poisons and some ions on the MTX determination were investigated using CQDs at the constant concentration of MTX50 pmol L-1 and various concentrations of other species. The results show excellent selectivity for the measurement of MTX in the presence of other similar species.