Nanopore Detection of Small Molecules Based on Replacement and Complexation Chemical Interactions

Small molecules play important roles in a variety of biological processes such as metabolism, cell signaling and enzyme regulation, and can serve as valuable biomarkers for human diseases. Moreover, they are essential to drug discovery and development, and are important targets for environmental monitoring and food safety. Due to the size incompatibility, small molecule transport is difficult to be monitored with a nanopore. A popular strategy for nanopore detection of small molecules is to introduce a molecular probe as a ligand (or recognition element) and rely on their effect on the ligand transport. One limitation for this sensing strategy is that the probe molecule needs to have a slightly smaller size than the nanopore constriction or can be easily unfolded or unzipped through the pore. Herein, by taking advantage of replacement and complexation chemical interactions, a generic approach is reported for detection of small molecules by using large biomolecules with well-defined stable 3D structures such as aptamers as recognition elements. Given the versatile use of aptamers as capture agents for a wide variety of species, the developed nanopore sensing strategy should find applications in many fields.