Tannic acid modified single nanopore with multivalent metal ions recognition and ultra-trace level detection

Artificial single nanopore as a promising tool for chemical and biological studies, such as ionic detection, DNA sequencing, molecular sensing/separation, nanofluidics and biomimetics, has been attracting great attention. Here we show a reliable functional single glass nanopore system with tannic acid to provide polyphenolic functional groups that possess specific binding affinities able to achieve metal ions recognition and ultra-trace level detection (e.g., limit of Fe3+ detection is down to 10−15 M). This system displays fast and high sensing ability features for detecting multivalent metal ions. Theoretical calculation (Gaussian 16) and experiments demonstrate that the specific binding energy between the trihydroxy phenolic groups of the inner surface of the nanopore and multiple metal ions can effectively distinguish trivalent, divalent, and monovalent metal ions. Therefore, our new system could promote a potential to conveniently recognize multivalent metal ions in nanoconfined space, and spark efforts to mimic ionic transport in biological nanopore systems and exploit smart nanofluidic devices.