Partitioning of propranolol in the phospholipid bilayer coat of anionic magnetoliposomes

Abstract

This work deals with the partitioning of the cationic amphiphilic drug, propranolol, in thecoating of so-called magnetoliposomes (MLs), which consist of nanometre-sized,magnetizable iron oxide cores covered with a phospholipid bilayer. MLs of two types wereused: either the ML coat consisted entirely of anionic dimyristoylphosphatidylglycerol,or it was mixed with zwitterionic dimyristoylphosphatidylcholine in a5/95 molar ratio. To separate sorbed from non-sorbed propranolol, high-gradient magnetophoresiswas used. The sorption profiles clearly show that electrostatic interactions play a key rolein the sorption process as drug incorporation in the ML coat was favoured byincreasing the anionic character of the ML envelope and by reducing the saltconcentration of the medium. Also, upon drug binding some phospholipid moleculeswere expelled from the ML coat. The observations may be of relevance in thebiomedical field, i.e. in the development of ML-based, intracellular theranostics.