Rational construction of a robust nanoprobe for highly selective and sensitive nitrite and formaldehyde detection and imaging in real foods.

Nitrite (NO) and formaldehyde (FA) are practice common food hazards, seriously threatening human health. Herein, for the first time a de novo nanoprobe, named MTB, with a single response group exhibiting different optical signals for NO/FA was reported, which had the following characteristics: i) An adamantane-labeled small molecule NI-adH grafted with polycyclodextrin (Poly-β-CD) to form MTB with excellent water-solubility and biocompatibility. ii) O-phenylenediamine (OPD) with photoinduced electron transfer (PET) played both a fluorescence quencher and as NO/FA trappers. Interestingly, fixed on pH6.0, OPD rapidly reacted with NO forming triazoles, inhibiting the PET effect and releasing bright fluorescence at 530 nm. While adding FA, OPD ultrafast formed Schiff-base, and MTB absorption red-shifted from 452 nm to 545 nm. Moreover, MTB exhibited excellent selectivity, high sensitivity (21.8 nM/17.1 nM), and rapid response towards (60 s/65 s) NO/FA. Impressively, MTB has been successfully adopted to detect NO/FA in real foods with satisfactory results.