Laccase biosensor based on screen-printed electrode modified with thionine-carbon black nanocomposite, for Bisphenol A detection

The relevance of Bisphenol A (BPA) in human health is well-known. For this reason we designed and developed a biosensor based on a bionanocomposite (laccase-thionine-carbon black)-modified screen-printed electrode. Thionine, a commercially available dye, was used as electrochemical mediator coupled with a nanostructured carbon black. By means of cyclic voltammetry, the interaction of thionine adsorbed on modified screen printed electrode with laccase/BPA reaction products has been studied. In addition, the immobilization of laccase by physical adsorption on the surface of thionine-carbon black modified screen printed electrodes was investigated. The response of the biosensor has been optimized in terms of enzyme loading, pH and applied potential reaching a linear concentration range of 0.5-50 μM, a sensitivity of 5.0 ± 0.1 nA/μM and a limit-of-detection (LOD) of 0.2 μM. The developed biosensor has been also challenged in tomato juice samples contained in metallic cans where release of BPA due to the epoxy resin coating can be assumed. A satisfactory recovery value comprised between 92% and 120% was obtained.