5G smartphone-adaptable fluorescence sensing platform for simultaneous detection of toxic formaldehyde and phosgene in different emission channels

Formaldehyde (FA) and phosgene are toxic volatile organic compounds (TVOCs) that pose serious threats to environment and human health. Herein, we rationally designed a fluorescent sensing platform Nap-NH2 for the detection of FA and phosgene in different emission channels. Upon an aldimine condensation reaction with FA, Nap-NH2 exhibited a significant fluorescence "turn-on" response at 551 nm with high selectivity and a low detection limit (62 nM). In contrast, Nap-NH2 underwent a specific nucleophilic reaction with phosgene, trig-gering a fluorescence band at 487 nm with fast response and a low detection limit (23 nM). The sensor was fabricated into cheap and portable test strips, which showed differentiable fluorescence colors and response rates to determine FA and phosgene. A smartphone containing RGB color detector was used to record the fluorescence pictures of test strips in the presence of FA or phosgene, and quantitatively determine the levels of FA and phosgene. Furthermore, Nap-NH2 test strips coupled with 5G mobile smartphone realized remote online monitoring gaseous phosgene and FA. Therefore, this 5G smartphone-adaptable fluorescence sensing platform has great potential applications in environment and public security.