Gold Nanoparticle-Decorated Single-Walled Carbon Nanotubes as a Catalytic Amplification Platform for the Electrochemical Detection of Alkaline Phosphatase Activity

The detection of alkaline phosphatase (ALP) activity is of great significance in many biomedical applications and for understanding the functional mechanism of ALP-related biological events. A sensitive electrochemical ALP biosensor using ascorbic acid 2-phosphate (AA-P) as the substrate was developed based on a gold nanoparticle-decorated single-walled carbon nanotube (GNP/SWNT)-modified glassy carbon electrode (GCE). The activity of ALP was determined indirectly according to the concentration of ascorbate (AA), which was generated during the hydrolysis reaction of AA-P in the presence of ALP as a catalyst. The biosensor exhibited a low applied potential, high sensitivity and selectivity, and the current response increased with ALP concentration from 3 to 50 U L-1 with a detection limit of 0.2 U L-1. The applicability of the developed method was demonstrated for successfully detecting ALP in whole HeLa cell lysate, thus providing a promising tool for other sensing systems that involve ALP.