Horseradish peroxidase biosensor based on layer-by-layer technique for the determination of phenolic compounds

An amperometric biosensor, based on layer-by-layer self-assembly of horseradish peroxidase (HRP) multilayers built up on a thiol-modifed gold surface, has been used for the detection of phenolic compounds. Optimization of the parameters has been performed with regard to the number of assembled bilayers, operating potential and the concentration of hydrogen peroxide. In the optimized conditions, the biosensor presented a linear response for catechol from 6 to 120 μmol l−1, with a sensitivity of 48.91 μmol l−1 nA and a detection limit of 0.7 μmol l−1. The response time of the biosensor for phenolic compounds was very short, reaching 95% of its maximum response in about 2 s. The differences in sensitivity observed for a series of phenolic substrates were discussed in terms of the stability of the oxidized phenolic compounds and the properties of substituents.