Colorimetric detection of pyrophosphate using gold nanorods and Fe3+ based on anti-etching mechanism

Pyrophosphate (PPi), as a derivative of inorganic phosphate, has important applications in the fields of food and environment, it also plays an important role in biological metabolism and serves as a biomarker for clinical diagnosis of certain diseases. Thus, the development of a simple and convenient method to quantify PPi is of great significance for environmental protection, food safety and disease diagnosis. In this study, visual colorimetric detection of PPi was achieved by inhibiting the morphological change of gold nanorods (Au NRs). In the presence of SCN - , Fe 3+ with low concentration can oxidatively etch Au NRs due to the potential difference, leading to significant color change of Au NRs solutions and blue shift in longitudinal local surface plasmon resonance (LSPR) absorption peak of Au NRs solutions. Due to the strong complexation between PPi and Fe 3+ , the etching of Au NRs by Fe 3+ was restrained, while the morphology of Au NRs, the color and UV–vis absorption spectrum of Au NRs solution remained uninfluenced. Under optimal conditions, this colorimetric detection method exhibited exceptional selectivity, anti-interference, and sensitivity towards PPi, with a linear detection range of 0.8–24 μM. Moreover, practical application results suggest that this colorimetric method holds significant potential for swiftly detecting PPi in intricate samples.