Construction of ratiometric fluorescence sensor and test strip with smartphone based on molecularly imprinted dual-emission quantum dots for the selective and sensitive detection of domoic acid

Domoic acid (DA), a highly neurotoxic metabolite produced by phytoplankton, contaminates seafood products and threats humankind. Herein, we have proposed a molecular imprinting fluorescence sensor with internal standard ratiometric mode for sensing of DA in seafood and seawater. In this study, the silicon-coated blue luminous carbon dots (B-CDs@SiO2) and CdTe acted as reference probe (430 nm) and response probe (610 nm), respectively. Subsequently, the two probes were assembled and the molecularly imprinted polymer (MIP) was introduced as the recognition element to construct the core component of the sensor (B-CDs@SiO2/CdTe MIP). When DA exists, it can be specifically adsorbed by the amino-rich imprinted sites on surface of B-CDs@SiO2/CdTe MIP and further assembled into the hydrogen-bonds complex, which can lead to the decrease in the fluorescence signal of MIP at 610 nm owing to the electron transfer from CdTe to DA. However, the fluorescence signal of MIP at 430 nm is not affected because of the protection of silica layer. Based on this principle, the designed internal standard ratiometric fluorescence sensor reveals high sensitivity, excellent selectivity, and wide linear range of 0.03-1 μM with a detection limit of 18 nM. Further, the portable fluorescent test strip with smartphone has been designed for semi-quantitative sensing of DA, which has potential application prospects for field analysis.