Approach for the electrochemical analysis of hydrophobic compounds included in photo-responsive liposomes

Abstract

A highly hydrophobic porphyrin: di-octadecyl-amide deuteroporphyrin (D-ODA) was synthesized and incorporated into liposomes (Lipo-D-ODA) through self-assembling of the aliphatic chains. From the fluorescence spectra, it was concluded that the long alkyl carboxylate chains accommodate the sensitizer into the lipid bilayer, is less exposed to quenching induced by aggregation. The light excited liposome Lipo-D*-ODA activated the ground state molecular oxygen to produce oxygen singlet or superoxide anion. The electrochemical responses of two structurally different redox-active analytes were studied. Quercetin oxidation at 200 mV was only observed after irradiation on the Lipo-D-ODA/Quercetin, indicating that it is embedded in the liposome and requires membrane rupture. On the contrary, the signal of Ferrocene-ODA was independent of irradiation because the redox polar moieties (Ferrocene) were oriented in aqueous space.