Nucleic acid aptamers improving fluorescence anisotropy and fluorescence polarization assays for small molecules

Abstract

Affinity probes, such as nucleic acid aptamers, have been combined with fluorescence anisotropy (FA)/fluorescence polarization (FP) technology for the development of a diverse range of assays. Formation of a complex between a small fluorescent molecule and its binding partner usually increases the overall size of the fluorescent molecule and decreases its rate of rotation, resulting in increases in fluorescence anisotropy/polarization. Structure-switching of the fluorescently labeled aptamers arising from target binding can also affect molecular volume, local rotation of the fluorophore, and/or fluorescence lifetime, causing changes in anisotropy/polarization. Incorporation of the unique adsorptive properties of single-stranded nucleic acid aptamers on nanomaterials, hybridization of aptamers with complementary sequences, and the amplifiable ability of nucleic acid aptamers have broadened the applications of fluorescence anisotropy assays and enhanced their sensitivity. This review focuses on nucleic acid aptamer-based fluorescence anisotropy assays for the detection of small molecules, such as therapeutic drugs, environmental contaminants, natural toxins, and metabolites.