Molecularly imprinted optosensing sensor for highly selective and sensitive recognition of sulfadiazine in seawater and shrimp samples

Two types of molecularly imprinted silica layers appended to quantum dots (MIP-QDs) for sulfonamides (SAs) were fabricated using reverse microemulsion surface grafting with 3-aminopropyltriethoxysilane as a functional monomer and sulfadimethoxine (SDM) and sulfadiazine (SDZ) as template molecules. The characterizations of both MIP-QDs were analyzed by ATR-FT-IR, SEM, and TEM, and their imprinting and specific fluorescence quenching mechanisms were elucidated through selectivity fluorescence response experiments. Finally, the MIP-QDs synthesized with SDZ as template exhibited excellent selective fluorescence quenching properties, which were attributed to the complementary imprinting cavities of the MIP-QDs to the templates and to the specific interactions between the functional monomer and the template molecules. Furthermore, a selective MIP-QD-based fluorescence optosensing sensor for the highly selective and sensitive recognition of SDZ was developed and successfully applied to detect SDZ in sea-water and shrimp samples. Under optimal conditions, linear relationships with correlation coefficients 0.9971 were obtained along the range of 0.005-1.5 mg/L to SDZ. The limit of detection was 0.004 mu g/L and 0.79 mu g/kg for SDZ in seawater and shrimp samples, respectively. Excellent recoveries (82.7-99.9%) with a relative standard deviation (below 6.1%) were obtained for both samples spiked with three levels of SDZ. The proposed MIP-QD method provides a powerful tool for the rapid and sensitive determination of SDZ in real samples. (C) 2017 Elsevier B.V. All rights reserved.