Organic molecular passivation of phosphorene: An aptamer-based biosensing platform

Black phosphorus (BP), also known as phosphorene (PP), is a fascinating two-dimensional (2D) material with extraordinary anisotropic mechanical, electronic and optoelectronic properties. However, PP is sensitive to oxygen and moisture and is completely degenerated by oxygen and humid air within 12 h, which limits its applications. Here, we coat PP with hexamethylenediamine (HMA), which allows the coated PP to maintain its original form in aqueous solution for over one month. The stable PP is dotted with gold nanoparticles to facilitate binding to a 3,3'4,4'-polychlorinated biphenyl (PCB77) aptamer (ap) as a biosensor. The aptamer biosensor based on gold nanoparticle-dotted PP nanocomposites (PP-AuNPs) exhibits superior analytical performance, and its sensitivity (391.1 μA cm^-2) is approximately three times higher than that of an AuNP-based sensor (AuNP-Ap/Au electrode, 147.2 μA cm^-2). This biosensor has a low detection limit (DL) of 33 pg L^-1 toward PCB77 with a dynamic response range toward PCB77 from 100 pg L^-1 to 10 μg L^-1. This research opens up avenues for the use of PP to make multiplexed diagnosis platforms in aqueous systems.