Advanced Biosensors: Electrochemical Impedance Study of Hybrid Materials Based on Layered Double Hydroxide/Trypsin

Immobilization of active Trypsin in Layered Double Hydroxides (LDH) has been successfully obtained by soft chemistry processes through coprecipitation and anion exchange reaction. Thin films of bioactive LDH-Trypsin membranes were coated on gold electrode for measurements of biosensing response toward a model substrate, N-Benzoyl-L-Arginine Ethyl Ester (BAEE). The adhesion and conductivity performance of the films were significantly enhanced by a chemical treatment of gold surface and Zn₂Al LDH by mercaptoethane sulfonate anion (MS). LDH-Trypsin based biosensors were studied by Electrochemical Impedance Spectroscopy and charge transfer mechanisms were investigated using Nyquist diagram simulation using electrical equivalent circuits. Nanostructuration of Zn₂Al-MS and Zn₂Al-MS-Trypsin at the surface of gold and MS modified gold electrodes have a strong influence on the protonic conductivity of the biosensor.