An Amperometric Biosensor for trans‐Resveratrol Determination in Aqueous Solutions by Means of Carbon Paste Electrodes Modified with Peroxidase Basic Isoenzymes from Brassica Napus

The catalytic properties of peroxidase basic isoenzymes (PBI's) from Brassica napus towards trans‐resveratrol (t‐Res) oxidation were demonstrated by the first time by conventional UV‐visible spectroscopic measurements. The enzymatic reaction rate was studied under different experimental conditions and the kinetics parameters were determined. An amperometric biosensor based on Brassica napus PBI's to determine t‐Res is also proposed by the first time. The method employs a dialysis membrane covered, PBI's entrapped and ferrocene (Fc)‐embedded carbon paste electrode (PBI's‐Fc‐CP) and is based on the fact that the decreased amount of H₂O₂ produced by the action of PBI's is proportional to the oxidised amount of t‐Res in the solution. Comparative amperometric experiments showed that, in spite of PBI's activity was much lower than commercial horseradish peroxidase (HRP) activity, t‐Res was a much better substrate for PBI's biosensors than those biosensors constructed by using HRP. The PBI's‐Fc‐CP biosensors showed a very good stability during at least twenty days. The reproducibility and the repeatability were 4.5% and 8.3%, respectively, showing a good biosensor performance. The calibration curve was linear in the t‐Res concentration (c_t‐Res) range from 1×10^?6 to 2.5×10^?5 M, with a sensibility of (2.31±0.05)×10⁶ nA M^?1. The lowest c_t‐Res value measured experimentally for a signal to noise ratio of 3 : 1 was 0.83 μM.