One-pot synthesis of luminol–gallium nanoassemblies and their peroxidase-mimetic activity for colorimetric detection of pyrophosphate

Abstract

A one-pot approach has been demonstrated for the synthesis of amorphous luminol–gallium (Ga) nanoassemblies, which are formed by small particles with big irregular spheres or network nanoassemblies. Moreover, luminol–Ga nanoassemblies exhibit peroxidase-mimetic activity toward the oxidation of peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H₂O₂) owing to its stimulating effect on the formation of reactive oxygen groups, such as hydroxyl radicals (OH˙). After the addition of luminol–Ga nanoassemblies to the TMB–H₂O₂ system, a remarkable color change is observed from colorless TMB to its blue product TMBox accompanied by an absorption peak at around 652 nm. Owing to the presence of reactive oxygen groups by luminol–Ga nanoassemblies, the peroxidase-mimetic activity is inhibited by PPi. Accordingly, the blue color fades away and the absorbance at 652 nm is decreased. Herein a novel sensitive colorimetric detection of PPi from 0.5 to 15 μM using luminol–Ga nanoassemblies is developed with the limit of detection (LOD) of 62.4 nM. The practicability of the assay toward the detection of PPi is also investigated in real water analysis such as lake water and tap water. Recoveries from 97.3% to 102.6% in local lake water and tap water samples are obtained. Therefore this cost-effective peroxidase-based analysis using luminol–Ga nanoassemblies is a potentially powerful tool for the quantitative determination of PPi in environmental samples.