A novel biosensor based on horseradish peroxidase trapped in silica Sol-Gel/MWCNTs matrix for methyldopa determination in medical and pharmaceutical samples

A modified electrode composed of horseradish peroxidase (HRP) trapped onto silica Sol-Gel/multi-walled carbon nanotubes (MWCNTs) matrix on carbon paste electrode (CPE) developed and applied for determination of methyldopa by electrocatalytic oxidation of methyldopa with HRP for the first time. The proposed biosensor showed linear response in two ranges of 1 μmol L-1 to 3.5 mmol L-1 and 3.5 mmol L-1 to 12 mmol L-1, and detection limit was obtained about 25.3 nmol L-1. The biosensor performance was much better than a lot of previously reported sensors and biosensors for methyldopa determination. This modified electrode was successfully used for accurate determination of methyldopa in urine and pharmaceutical samples. Using the developed biosensor provided an accurate, sensitive and repeatable method for methyldopa measurement in pharmaceutical and urine samples.