Electrochemistry in large unilamellar vesicles. The distribution of 1-naphthol studied by square wave voltammetry

1-Naphthol (NPh) behavior in water and in large unilamellar vesicles (LUVs) formed with the phospholipid 1,2-di-oleoyl-sn-glycero-3-phosphatidylcholine (DOPC) was studied by square wave (SWV) and cyclic voltammetry (CV) techniques and, compared with emission spectroscopy studies. In DOPC LUV media, the redox behavior of NPh shows that the molecule undergoes a partition process between two pseudophases, the water and the LUV bilayer. The NPh electrochemical responses allow us to propose a model to explain the electrochemical experimental results and, in conjunction with our measurements, to calculate the NPh partition constant (K) value between the pseudophases. The K value coincides with the one obtained through emission spectroscopy. Beside the K value, our electrochemical model allows us to calculate the diffusion coefficient (D_LUV) for DOPC LUV which coincides with the D_LUV value obtained through dynamic light scattering (DLS). Thus, our data clearly show that the electrochemical measurements could be a powerful alternative approach to investigate the behavior of non-ionic electroactive molecules embed in a confined environment such as the LUV bilayer.