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Updated: Jan 23, 2026

Colorimetric Analysis of Alkaline Phosphatase Activity in S. aureus Biofilm
Published on: April 12, 2019
MnO2 nanosheets as oxidase mimics for colorimetric detection of alkaline phosphatase activity
Fengyu Tian1,2,3, Jing Zhou1,2,3, Jing Ma3
1Laboratory of Quality & Safety Risk Assessment for Citrus Products (Chongqing), Ministry of Agriculture, Citrus Research Institute, Southwest University, Chongqing, 400712, People's Republic of China.
Abstract:
A sensitive colorimetric method is described for the determination of the activity of alkaline phosphatase (ALP). It is based on the regulation of the oxidase-mimicking activity of MnO2 nanosheets. In the absence of ALP, MnO2 nanosheets are capable of catalyzing the oxidation of the colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) by oxygen to form a blue oxidized product (TMB Ox) with an absorption peak at 652 nm. In the presence of ALP and its substrate ascorbic acid-2-phosphate, the latter is hydrolyzed to form ascorbic acid (AA). AA triggers the decomposition of MnO2 nanosheets by reducing MnO2 to Mn2+, thereby weakening the enzyme mimicking activity of the MnO2 nanosheets and causing a drop in absorbance. The drop in absorbance at 652 nm is related to the ALP activity in the range from 0.05-10 m-units per mL (mU·mL-1), and the detection limit is 0.05 mU·mL-1. The method was applied to the determination of ALP in spiked calf serum samples and gave satisfactory results. Graphical abstract Schematic presentation of a facile and sensitive colorimetric method for detecting the activity of alkaline phosphatase (ALP) based on enzymatic regulation of the oxidase-mimicking activity of MnO2 nanosheets.
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