Nanoarchitectonics of Small Molecule and DNA for Ultrasensitive Detection of Mercury

Reliable and ultrasensitive detection of mercury ions is of paramount importance for toxicology assessment, environmental protection, and human health. Herein, we present a novel optoelectronic approach based on nanoarchitectonics of small-molecule templated DNA system that consists of an adenine (A)-conjugated small organic semiconductor (BNA) and deoxyribo-oligothymidine (dTn). This mutually templated dynamic chiral coassembly system (BNAn-dTn) with tunable chiroptical, morphological, and electrical properties is tapped in to enable ultrasensitive and selective detection of inorganic and organometallic mercury in water. We observe a rapid transformation of the BNAn-dTn coassembly into a metallo-DNA duplex [dT-Hg-dT]n in the presence of mercury, which is utilized for a chiro-optical and conductivity-based rapid and subnanomolar sensitivity (≥0.1 nM, 0.02 ppb) to mercury ions in water (∼100 times lower than United States Environmental Protection Agency tolerance limit). This ultrasensitive detection of inorganic and organometallic mercury is driven by a novel chemical design principle that allows strong mercury thymine interaction. This study is anticipated to inspire the development of future templated DNA nanotechnology-based optoelectronic devices for the rapid and ultrasensitive detection of numerous other toxic analytes.