Enzymes encapsulated in organic–inorganic hybrid nanoflower with spatial localization for sensitive and colorimetric detection of formate.

[Display omitted] • FOx and HRP were co-immobilized in organic–inorganic hybrid nanoflower. • FOx@HRP showed good catalytic activity owing to spatial localization of enzymes. • FOx@HRP could be applied in the sensitive and colorimetric detection of formate. • FOx@HRP possessed ideal stability and reusability in the detection of formate. Formate is an important environmental pollutant, and meanwhile its concentration change is associated with a variety of diseases. Thus, rapid and sensitive detection of formate is critical for the biochemical analysis of complex samples and clinical diagnosis of multiple diseases. Herein, a colorimetric biosensor was constructed based on the cascade catalysis of formate oxidase (FOx) and horseradish peroxidase (HRP). These two enzymes were co-immobilized in Cu 3 (PO 4) 2 -based hybrid nanoflower with spatial localization, in which FOx and HRP were located in the shell and core of nanoflower, respectively (FOx@HRP). In this system, FOx could catalyze the oxidation of formate to generate H 2 O 2 , which was then utilized by HRP to oxidize 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid to yield blue product. Ideal linear correlation could be obtained between the absorbance at 420 nm and formate concentration. Meanwhile, FOx@HRP exhibited excellent detection performance with low limit of detection (6 μM), wide linear detection range (10–900 μM), and favorable specificity, stability and reusability. Moreover, it could be applied in the detection of formate in environmental, food and biological samples with high accuracy. Collectively, FOx@HRP provides a useful strategy for the simple and sensitive detection of formate and is potentially to be used in biochemical analysis and clinical diagnosis. [ABSTRACT FROM AUTHOR]