Fluorescent self-propelled covalent organic framework as a microsensor for nitro explosive detection

Covalent-organic-frameworks (COFs) are an emerging class of porous materials with fascinating struc- tural features desired for a wide spectrum of applications. However, the potential sensing applications of COFs are hindered by their hydrophobic nature, as well as limited detection speed and sensing sensitivity. We report a fluorescent self-propelled COF as a microsensor for highly efficient nitro explosive detec- tion. Together with MnO2 microsphere catalysts and magnetic Fe3O4 nanoparticles, the fluorescent COF is built in biodegradable polymeric spheres. The resulting microsensors can exhibit magnetically guided autonomous motion in aqueous solution. Fluorescence quenching of the microsensors is observed upon their navigation in solutions with trace amounts of explosives. Continuous mixing induced by the bub- ble propulsion of microsensors greatly shortens the sensing time to several minutes. We anticipate the presented strategy would provide implications for sensing applications of COFs. (C) 2020 Elsevier Ltd. All rights reserved.