Langmuir–Blodgett films incorporating redox mediators for molecular recognition of NADH

We focused our studies on the fabrication of nano-organized systems incorporating redox mediators for NADH. We fabricated gold-modified electrodes of phospholipid layers containing a redox mediator for NADH by means of the Langmuir–Blodgett (LB) technique. We chose tetramethylbenzidine (TMB) which is known to decrease the very large overvoltage involved in the direct oxidation of NADH. The electrochemical characterisation of the films allowed to determine the presence and the electrochemical activity of the mediator in the LB layers. The response of the sensing layer in solutions containing NADH was investigated by means of cyclic voltammetry and fluorescence spectroscopy. We observed that NADH has a strong affinity with the film, and it interacts with the TMB-containing phospholipid layers. In fact, we found that TMB molecules mediate the NADH oxidation reaction, even if the surrounding matrix relatively hinders their mobility.