A turn-on fluorescent nano-probe base on methanobactin-AuNPs for simple and efficient detection of nitrite

•Methanobactin is a fluorescent molecular peptide obtained by fermentation.•Methanobactin and gold nanoparticles form Mb-AuNPs fluorescent probe through Au-S.•The detection is based on the diazo coupling reaction-triggered intensity change.•The method exhibits good selectivity and reliability.•The method can be used for detection of nitrite in actual food samples.