Room temperature phosphorescent determination of aflatoxins in fish feed based on molecularly imprinted polymer - Mn-doped ZnS quantum dots.

Possibilities of room temperature spectrometry based on Mn-doped ZnS quantum dots coated with a molecularly imprinted polymer based nanosensor have been explored for the sensitive and selective determination of aflatoxins. Synthesized polymeric nanoparticles exhibit intense room temperature phosphorescence (total decay time of 0.004 s) and aflatoxins quench the room temperature phosphorescence when interact with the recognition cavities of the molecularly imprinted polymer attached to the phosphorescent quantum dots. Room temperature phosphorescence was recorded by scanning from 520 nm to 720 nm (maximum peak intensity at 594 nm) after excitation at 290 nm. The prepared imprinted material was found to have higher adsorption capacity than those based non-imprinted quantum dots, demonstrating high adsorption uptake for aflatoxins. In addition, selectivity studies have demonstrated that the material offers a specific recognition for aflatoxins. Room temperature phosphorescence quenching by aflatoxins was found to be linear within the 2-20 μg L^-1 range, and a limit of detection of 3.56 μg kg^-1 was obtained. This value was lower than the maximum acceptable/residual level (aflatoxins in feeds) published by the European Commission. The results indicate a simple room temperature phosphorescence nanosensor for aflatoxins detection in fish feed as a versatile tool having excellent sensitivity and selectivity.