Enhancing biosensor capabilities through laccase immobilization in nanostructured Langmuir-Blodgett films for phenol detection

Fabricating nanoscale structures combining various elements with specific functionalities is a pertinent strategy for enhancing sensor capabilities. In this study, we immobilized Laccase (Lac) in a biomimetic environment provided by a nanostructured Langmuir-Blodgett (LB) film of an amphiphilic material (octadecylamine, ODA), where poly(3-hexylthiophene-2,5-diyl) (P3HT) has been coimmobilized as the electron mediator. Tensiometry demonstrates that the enzyme is incorporated in the floating monolayers efficiently. The monolayers were transferred to solid substrates as LB films and characterized using UV-vis and infrared spectroscopies and Atomic Force Microscopy, exhibiting a quasi-ordered structure with low roughness. The films' ability to detect phenols was evaluated through enzymatic activity estimation using colorimetric and voltammetry measurements against vanillin, catechol, and pyrogallol. Our results demonstrate that the electrochemical response depends on the phenol's nature, with limits of detection for vanillin, catechol, and pyrogallol at 1.10.10(-6), 2.13.10(-7), and 2.07.10(-7) mol.L-1, respectively. Additionally, the intensity of the response does not correlate with film thickness, confirming that the electrochemical reaction is a surface phenomenon for catechol and pyrogallol. We believe this study provides valuable insights into phenol detection in the food industry, which is crucial for ensuring food safety, quality, and authenticity by aiding in regulatory compliance, process optimization, and product preservation.