Authors: S.R. Jadhav, R. Mark Worden
Affilation: Michigan State University, United States
Pages: 336 - 339
Keywords: supported bilayer lipid membrane, PAMAM dendrimers, cyclic voltammetry, impedance
Polyamido-amine (PAMAM) dendrimers are hyperbranched polymers with uniform particle size making them ideal monodisperse nanoparticles. PAMAM dendrimers are being pursued as non-viral vectors for gene delivery due to their low immunogenicity and their ability to rupture bilayer lipid membrane. In the present study, a supported bilayer lipid membrane (sBLM) was deposited on a glassy carbon electrode using 1,2-dioleoyl-sn-glycero-3-phosphocholine lipids. The sBLM formation and the interaction of different PAMAM dendrimers with carbon sBLM were investigated using electrochemical techniques. PAMAM dendrimers of different generation (G2-G7) were tested for their effect on carbon sBLM. It was found that the low generation dendrimers (G2-G4) primarily adsorb on the sBLM surface without causing much damage to the membrane. Higher generation dendrimers (G5-G7), however, were found to cause the rupture of sBLM creating large defects in sBLM. The rupture ability was quantified using cyclic voltammetry studies wherein the peak current obtained for the ferricyanide reduction increases proportionally with the area of BLM ruptured. Impedance results showed that the ruptured bilayer gave higher capacitance values suggesting that the BLM surface coverage has decreased. The results suggest that the molecular shape, size and surface charge density are the critical factors determining the BLM rupture ability of the dendrimer. The dendrimers with the dimension equal to or greater than bilayer thickness are more effective in causing defects in BLM. Higher generation dendrimers also offer higher charge density which enhances their BLM rupturing ability. The study provides valuable evidence supporting the use of PAMAM dendrimers as potential gene delivery vehicles.