Effects of amine and amine oxide compounds on the zeta-potential of emulsion droplets stabilized by phosphatidylcholine

A positively charged submicron emulsion based on phospholipid was suggested and their surface electrical properties were investigated at various pHs. Additives used to change the zeta potential of emulsion were decyldimethylamine oxide (DeDAO), dodecyldimethylamine oxide (DDAO) stearylamine (SA) and dodecylamine (DA). Also the emulsion droplet size and size distribution were measured to study the effects of additives on the emulsion properties. By adding additives, the zeta potential of emulsion droplet has been significantly changed but there were little effects on emulsion size and size distribution. In a wide range of pH (≈8.0), all additives yielded the positive zeta potential values. But at pH 10, amine compounds generated the negative-charged emulsion droplets while amine oxide compounds generated the neutral emulsion droplet. From this study, it was found that amine oxide compounds as well as amine compounds can be used to modify the zeta potential of emulsion droplets from negatively charged to positively charged below pH 8.0 for the effective drug delivery vehicles.