Development of a selective fluorescence nanosensor based on molecularly imprinted-quantum dot optosensing materials for saxitoxin detection in shellfish samples

Abstract A new type of molecularly imprinted silica layers appended to quantum dots (MIP-QDs) for saxitoxin (STX) was fabricated through the surface grafting technique. The MIP-QDs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), and imprinting and selective fluorescence quenching properties in different solutions. Results demonstrated that the synthesized MIP-QDs exhibited excellent selective fluorescence quenching to STX because of the complementary imprinted cavities on the surface of MIP-QDs. Furthermore, a fluorescence nanosensor based on MIP-QDs was fabricated for the selective detection of STX under optimal experimental conditions. A good linear relationship in the range of 20.0-100.0 μg/L with a correlation coefficient of 0.9988 was obtained. Excellent recoveries ranging from 89.4% to 102.4% with the RSD below 6.3% were obtained for the shellfish samples at three spiked levels of STX. The detection limit of STX in shellfish samples was 0.3 μg/kg. The results indicated that the developed fluorescence nanosensor was highly selective and sensitive enough to detect STX in shellfish samples.