Prussian Blue Nanoparticles with High Oxidase-like Activity for Simultaneous Detection of Ascorbic Acid and Alkaline Phosphatase in Real Samples

Prussian blue nanoparticles (PB NPs) have exhibited favorable anti-inflammatory effects in animal models, and have been proved to mimic three antioxidant enzymes: peroxidase, catalase, and superoxide dismutase. Whereas the oxidase-like activity of PB NPs has not been demonstrated. In this work, PB NPs with outstanding oxidase-like activity were demonstrated by virtue of the colorimetric substrate o-phenylenediamine (OPD). Interestingly, based on the oxidase-like activity, PB NPs can also catalytically oxidize vitamin B1 (VB1) to strongly fluorescent product in the physiological environment without the addition of other oxidants. Considering that VB1 has no toxicity and carcinogenicity comparing with OPD, a novel PB NPs-VB1 fluorescent sensor was further developed for simple, nontoxic, and rapid detection of ascorbic acid (AA) in foods and alkaline phosphatase (ALP) in human serum samples by taking advantage of the reduction of PB NPs to Prussian White by AA or enzymatic hydrolysate of ALP and ascorbic acid 2-phosphate (AA2P), leading to the decrease of fluorescence intensity. The extremely low detection limits of 44 nmol/L for AA and 72 mU/L for ALP as well as the excellent applicability in real samples were both obtained. Therefore, we envision that such a novel fluorescent probe would be potentially applied in the food analysis and clinic diagnosis fields.