Metal-Organic Polyhedra-Coated Si Nanowires for the Sensitive Detection of Trace Explosives.

Surface-modified silicon nanowire-based field-effect transistors (SiNW-FETs) have proven to be a promising platform for molecular recognition in miniature sensors. In this work, we present a novel nanoFET device for the sensitive and selective detection of explosives based on affinity layers of metal-organic polyhedra (MOPs). The judicious selection of the geometric and electronic characteristics of the assembly units (organic ligands and unsaturated metal site) embedded within the MOP cage allowed for the formation of multiple charge-transfer (CT) interactions to facilitate the selective explosive inclusion. Meanwhile, the host-stabilized CT complex inside the cage acted as an effective molecular gating element to strongly modulate the electrical conductance of the silicon nanowires. By grafting the MOP cages onto a SiNW-FET device, the resulting sensor showed a good electrical sensing capability to various explosives, especially 2,4,6-trinitrotoluene (TNT), with a detection limit below the nanomolar level. Importantly, coupling MOPs-which have tunable structures and properties-to SiNW-based devices may open up new avenues for a wide range of sensing applications, addressing various target analytes.