Development of Novel Electrochemical Biosensors Based on Horseradish Peroxidase for the Detection of Caffeic Acid

In this study, biosensors based on two types of screen-printed carbon and Prussian blue-carbon electrodes, respectively, modified with peroxidase extracted from horseradish root for the sensitive and selective detection of caffeic acid were developed. The presence of the enzyme in the aqueous extract and the activity of peroxidase was demonstrated by spectrometric methods. The electrochemical technique used for the determination of caffeic acid with the biosensors was the cyclic voltammetry. Calibration of the biosensors towards caffeic acid was carried out in solutions of different concentrations, ranging from 5 to 74 μM. Suitable sensitivities and detection limits for practical applications were obtained, with the more sensitive (0.72 μA·μM−1) one being the biosensor containing Prussian blue as a mediator of the exchange between electrons with a detection limit of 0.9 μM. Caffeic acid was successfully determined and quantified in three food supplements using the Prussian blue-peroxidase-based biosensor. The method used to validate the results obtained with the biosensor in the food supplements was a comparison with the amounts indicated by the producers, with no differences between the results at a 99% confidence level.