Amino-Functionalized Nano-UiO-66 for the Detection of Nerve Agent Analogs

The size modulation of metal–organic frameworks (MOFs) is of vital importance in many fields, especially in sensing for enhanced performance, while the synthesis of small-sized MOF nanocrystals with wide active reaction sites remains challenging. Here, we report a general sustainable strategy for building smaller, nanosized, self-assembled, film-forming UiO-66 with abundant active reaction sites via carboxylated cellulose nanofibril (CNF)-induced in situ growth. Benefiting from the remarkably boosted active site quantity, the eliminated background fluorescence, as well as the superior charge transfer between an amino group and an analyte, an efficient fluorescent platform for the detection of the nerve agent analog diethyl cyanophosphonate (DCNP) was established. Not only were a significantly low limit of detection (LOD, 4.2 nM/0.685 ppb) and robust selectivity against a wide range of common substances (>21 types) achieved, but an immediate response to DCNP vapor (<1 s) was also demonstrated by a sensing chip. We believe that the design of UiO-66 with nanosize and monodispersity would help advance the development of high-performance MOF-based fluorescence sensing devices.