Dual-mode strategy for 2,6-dipicolinic acid detection based on the fluorescence property and peroxidase-like activity inhibition of Fe-MIL-88NH2

[Display omitted] •A novel fluorometric/colorimetric dual-mode sensor for DPA detection was established based on Fe-MIL-88NH2.•The inhibitory effect of DPA on the peroxidase activity of Fe-MIL-88NH2 was investigated.•The method demonstrated good sensitivity, selectivity, and visual monitoring toward DPA. This work designed a fluorometric/colorimetric dual-mode sensor for detecting 2,6-dipicolinic acid (DPA) based on the blue emission property and peroxidase-like activity of Fe-MIL-88NH2. The fluorescence of Fe-MIL-88NH2 was obviously turned off by Cu2+, but DPA was able to bring it back because it has a strong chelate bond with Cu2+. Fe-MIL-88NH2 also displayed high peroxidase-like activity, which accelerated the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to the blue oxidation product (oxTMB) when H2O2 was present. When DPA was added, it efficiently inhibited the peroxidase-like activity of Fe-MIL-88NH2, causing less oxTMB and less absorbance at 652 nm. The fluorescence recovery of Fe-MIL-88NH2 and the change in absorbance at 652 nm were used as analytical signals for dual-mode detection of DPA. The linear responses in the range of 10–60 μM and 60–160 μM were achieved for the fluorometric mode, and the limit of detection (LOD) was 1.46 μM. The respective values of linear range and LOD for the colorimetric mode were 5–25 μM and 3.00 μM, respectively. In summary, the dual-mode testing strategy successfully detected DPA in aqueous environmental samples, suggesting great potential in disease prevention and environmental analysis.