Tunable catalytic activity of FeWO4 nanomaterials for sensitive assays of pyrophosphate ion and alkaline phosphatase activity

Alkaline phosphatase (ALP) activity and pyrophosphate ion (PPi) levels are remarkable for the human body functions such as signal transduction pathways and metabolism. Current quantitative methods mainly focus on developing complicated organic substrates or employing unstable metal ions as signal-regulated medium. Herein, we have developed a facile hydrothermal method for preparing FeWO 4 nanomaterials with intrinsic peroxidase-like activity and further confirmed that such a catalytic activity could be significantly enhanced by adjusting the size and oxygen vacancy content. More encouragingly, PPi can easily inhibit the catalytic activity of FeWO 4 , whereas orthophosphate ions (Pi) cannot. Therefore, we constructed an FeWO 4 -based colorimetric assay for sensing PPi by means of the classical 3,3′,5,5′-tetramethylbenzidine-peroxidase chromogenic reaction. A facile and reliable ALP activity assay was also designed and developed because of the logical regulation of the peroxidase-like activity of FeWO 4 through the ALP-catalyzed hydrolysis of PPi into Pi. Based on the clear mechanism and mimetic-enzyme FeWO 4 -catalyzed amplification, the sensing system exhibited excellent performance and was able to evaluate ALP activity in real serum samples and screen for potential ALP inhibitors. The proposed mimetic enzyme-involved colorimetric assay provides an alternative pathway, and FeWO 4 nanomaterials with excellent performance have great potential for further biosensing and biomedical applications.