Fluorescence-based aptasensors for small molecular food contaminants: From energy transfer to optical polarization

• For the first time, the fluorescence-based aptasensors are classified into groups “energy transfer” and “optical polarization” according to the generation mode of the fluorescent signal. • A systematic review of principle and application of the fluorescence-based aptasensors, from energy transfer to opitical polarization, are included in this paper. • Pertinent perspectives, challenges and solutions are given in order to inspire the practitioners working on the research and development of fluorescence-based aptasensors for small molecules. • This paper will provide insights to practical application in different scenarios and demand-driven design of fluorescence-based aptasensors for small molecules and other analytes. Small molecular food contaminants, such as mycotoxins, pesticide residues and antibiotics, are highly probable to be passively introduced in food at all stages of its processing, including planting, harvest, production, transportation and storage. Owing to the high risks caused by the unknowing intake and accumulation in human, there is an urgent need to develop rapid, sensitive and efficient methods to monitor them. Fluorescence-based aptasensors provide a promising platform for this area owing to its simple operation, high sensitivity, wide application range and economical practicability. In this paper, the common sorts of small molecular contaminants in foods, namely mycotoxins, pesticides, antibiotics, etc, are briefly introduced. Then, we make a comprehensive review, from fluorescence resonance energy transfer (in turn-on, turn-off, and ratiometric mode, as well as energy upconversion) to fluorescence polarization, of the fluorescence-based aptasensors for the determination of these food contaminants reported in the last five years. The principle of signal generation, the advances of each sort of fluorescent aptasensors, as well as their applications are introduced in detail. Additionally, we also discussed the challenges and perspectives of the fluorescent aptasensors for small molecular food contaminants. This work will offer systematic overview and inspiration for amateurs, researchers and developers of fluorescence-based aptasensors for the detection of small molecules.