Oxidation of a Phospholipid at an Electrode Modified with an Electrochemically Formed Sol-Gel Film Doped with Cyclodextrin

In aqueous, un‐buffered solution at a potential where H+ is generated in a tetraethylorthosilicate sol, nm‐scale deposits of silica on electrodes are formed. Inclusion of β‐cyclodextrin in the sol promotes electrochemical activity, presumably by producing channels in the otherwise‐passivating film. With the additional provision of inclusion of a redox mediator, RhII, the electrochemical oxidation of a representative phospholipid (PL), phosphatidylcholine (PC), is demonstrated; the process occurs without the passivation that otherwise precludes the voltammetric determination of PLs. By cyclic voltammetry, current proportional to PC concentration in the range 1–100 μM is achieved with the described electrode.