A Highly Sensitive Luminescent Upconversion Nanosensor for Turn-On Detection of As.

A luminescent nanoprobe (N), MnO-modified Er/Yb-codoped AgMoO upconversion nanoparticles (UCNPs; cod-AMO-3/MnO), was constructed for rapid, sensitive, and selective "turn-on" detection of trace As. Herein, two kinds of luminescent Ns were developed based on luminescence resonance energy transfer (LRET) between cod-AMO-3 as the energy donor and MnO as the energy acceptor. By using MnO as the matrix in cod-AMO-3/MnO fluorometric assay, the upconversion luminescence (UCL) intensity () of the cod-AMO-3 probe was quenched significantly through LRET, illustrating MnO as an efficient quencher for UCL. With the addition of As, a stable bidentate binuclear (BB) corner-sharing bridged complex (As-MnO) was probably formed, which alters the surface of the upconversion N, leading to gradual separation between UCNPs and MnO and subsequent recovery of . Interestingly, it possessed superior sensitivity, reaction kinetics, and also high selectivity toward As in aqueous solution. Our optimized cod-AMO-3/MnO nanocomposite (NComp) demonstrated a linear range of 0-150 ppb and an ultrasensitive detection limit of 0.028 ppb for As, which is extremely below the regulatory level, signifying the promising practical usage of this system. To the best of our knowledge, such a surface-modified Ln-codoped Ag-based nanosensor being applied for As detection probably has not been reported yet, and it is rather unexplored. In a nutshell, the ability to monitor the As concentration may enable the rational design of a convenient platform for a diverse range of environmental monitoring applications.