[Visualized and quantitative detection of horseradish peroxidase based on redox reaction boundary]

A new portable method for the detection of horseradish peroxidase (HRP) is reported in this paper. Visualized and quantitative detection of HRP was achieved based on the theory of electrophoresis titration (ET) and redox reaction boundary (RB). The ET-RB model was built on the 3,3',5,5'-tetramethyl benzidine chromogenic system because it significantly increases the efficiency of the chromogenic reaction and can react with L-ascorbic acid. A series of experiments were performed on a tiny and portable titration chip based on the material of polymethyl methacrylate designed for the developed model. The composition of the titration gel was optimized to ensure higher detection sensitivity and stable detection performance. The experimental results manifested a log-linear relationship between the moving distance of the RB and the HRP concentration. The dynamic range of the developed method ranged from 0.002 to 0.073 mg/L, and the detection could be accomplished within 10 min. Visualized and quantitative detection could be realized by reading the moving distance of the colored boundary with the naked eyes instead of using any signal-reading device or analyzing instrument. Thus, this method has great potential for further application to the development of a real-time detection method for various target substances based on the detection of peroxidase activity.