Formation Of EggPC Vesicles On Modified Electrode

Giant unilamellar vesicles (GUVs) of10-100m can be prepared byelectroformation method. Similar size and bilayer structure to bio-membrane, vesiclebecomes useful model for investigation the interactions between lipid memebranes andcollodial particles or macromolecules. It also can be widely used as the model of cellmembrane and drug carrier. Due to important influences of substrate properties on thevesicles formation, this paper introduces modified aluminum electrode and modified goldelectrode as working electrode respectively in the research of vesicle electroformation.High yield of giant vesicles are successfully formed on the two modified electrodes underan alternative current (AC) electric field. This paper elaborated the electroformation ofvesicles on the two modified electrodes as follows.Firstly, glyoxylic acid modified aluminum electrode (GA-Al) and L-acetylcysteinemodified gold electrode (AC-Au) were prepared by the electro-reduction of oxalic acidand the method of chemical adsorption, respectively. The modified layers of these twomodified electrode were characterized by scanning electron microscope (SEM). Theinteraction of electro-deficient of the aldehyde group have electron-rich groups in the eggphosphatidylcholine (EggPC) molecule, and the adsorption of L-acetylcysteine modifiedgold electrode with anionic or zwitterionic lead to the aggregation of EggPC molecule onthe surface of these two modified electrodes. Modified aluminum electrode and modifiedgold electrode play an important role in the electroformation of vesicles.Secondly, giant vesicles were obtained over a wide frequency range of1-3000Hzand peak-to-peak value from0.212V/mm to20V/mm between modified electrode andplatinum-wire electrode under AC electric field. The influences of AC voltage andfrequency on the structural evolution of giant vesicles were in situ observed by invertedoptical microscope. A large number of repeated experiments demonstrated that5V and10V is the optimal voltage for the formation of the vesicles on glyoxylic acid modifiedaluminum (GA-Al). It observed that the largest frequency of vesicles formation was10000Hz. Finally, we explored the vesicles formation on L-acetylcysteine modified goldelectrode (AC-Au) in distilled water and sodium chloride solution under three kinds ofrepresentative AC electric field parameter(5V/20Hz),(5V/100Hz),(7V/20Hz).