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

• A host–guest self-assembly nanoprobe MTB was constructed for NO 2 – and FA detection. • MTB can report FA, NO 2 –, and FA/NO 2 – with different optical signals. • MTB was successfully adopted to detect FA and NO 2 – in real foods samples. Nitrite (NO 2 –) 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 2 –/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 2 –/FA trappers. Interestingly, fixed on pH6.0, OPD rapidly reacted with NO 2 – 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 2 –/FA. Impressively, MTB has been successfully adopted to detect NO 2 –/FA in real foods with satisfactory results. [ABSTRACT FROM AUTHOR]