A novel quantum dots-labeled on the surface of molecularly imprinted polymer for turn-off optosensing of dicyandiamide in dairy products.

A novel optosensing system based on quantum dots (QDs)-labeled on the surface of a molecularly imprinted polymer (MIP) was developed for turn-off fluorescence sensing of dicyandiamide (DCD). The QDs were modified with silica to covalently adhere to the MIP surface, which resulted in a higher fluorescence quantum yield than MIP-coated QDs. Under optimal conditions, there was a linear relationship, with a correlation coefficient of 0.9950, between the fluorescence intensity and the DCD concentration over the range 5-1600 μmolL(-1). The detection limit of this system was 2.7 μmolL(-1). The proposed method exhibited with good recoveries ranging from 95% to 106%. Most importantly, the optosensing approach can be successfully applied for the determination of DCD in dairy products. With excellent sensitivity and selectivity, such simple and cheap materials are potentially suitable for monitoring of DCD in other food, in agriculture and for environmental applications.