A ratiometric fluorescent indicator-displacement assay for on-site determination and intracellular imaging of nitroxinil.

[Display omitted] • This work reported the first ratiometric fluorescent probe for nitroxinil. • The probe enables fast, sensitive and selective detection of nitroxinil. • On-site analysis in real food samples was available by using paper strips. • Fluorescence imaging of nitroxinil in Hela cells was successfully achieved. Nitroxinil (NIT) is a widely using veterinary medicine to protect cattle and sheep yet may threaten human health when ingested through food chain. Developing fluorescent analytical methods in ratiometric manners was essential for the on-site detection and in-situ monitoring of NIT but still challenging. Here, we improved the indicator-displacement assay (IDA)-based method and designed the first ratiometric fluorescent probe for NIT by using an albumin host and an Aggregation-induced emission (AIE) guest. This probe exhibited fast response (10 s), high sensitivity (limit of detection: 4.6 ppb), good selectivity (over twelve medicines) and eye-discriminable fluorescent color change (green–red) upon responding to NIT. Based on these properties, this probe enabled quantitative determination of NIT in real food samples, on-site analysis via a paper-based test strip, and fluorescence imaging of NIT in living cells. [ABSTRACT FROM AUTHOR]