Dual-chromophore-functionalized silica mesoporous nanoparticles for fast visual detection of nerve agent simulant DCP

In the present work, a mesoporous silica nanoparticle (MSN@RB-NA)-based fluorescent nanomaterial was developed for fast and selective detection of a nerve agent simulant, diethylchlorophosphate (DCP), where two chromophores, naphthalimide and rhodamine B, were co-functionalized on the surface of MSN through their silane derivatives. The successful immobilization of the two fluorescent derivatives on MSN was demonstrated by a variety of characterization methods including FT-IR, BET-BJH, XPS, TEM, TGA, and solid-state 13C NMR, etc. A filter-paper sensor based on the dual-chromophore-functionalized MSN was tested for DCP vapor detection. Fluorescence measurements revealed that DCP can induce fluorescence reduction of naphthalimide unit at 476 nm and enhanced emission of rhodamine B at 575 nm of the paper sensor. Control experiments reveal that the piperazine group connected with the naphthalimide unit is responsible for DCP recognition, and a FRET process from naphthalimide to rhodamine B is believed the reason for the observed enhanced rhodamine emission. The paper sensor exhibits high sensitivity to DCP vapor with detection limit at 4.58 ppb, excellent selectivity over other 17 interferents, and fast response speed (< 1 s). Moreover, the present work provides an easy way for fast visual detection of DCP vapor.