Microencapsulation of organic solvents in polyelectrolyte multilayer micrometer-sized shells

Hollow-shell micrometer-sized particles were fabricated in aqueous media by stepwise deposition of oppositely charged polyelectrolytes onto melamine l atex particles and biological cells with a dissolution of the core afterwar d. It is demonstrated that these shells can be suspended in various organic media, such as methanol, ethanol, pentanol, hexanol, octanol, octane, and decane, by a gradual solvent exchange. At this stage of the procedure the s hells contain the respective organic solvent. Oil suspensions in water are then formed by transferring the particles from the organic media into water , without the use of any further surfactant addition. By an additional adso rption step employing phospholipids, it is possible to obtain a dispersion of shells in organic solvents containing an aqueous solution inside. AFM me asurements are provided which show that the shells preserve their integrity in the different solvents. Confocal microscopy is employed to demonstrate encapsulation of solvents and the presence of lipids, (C) 1999 Academic Pre ss.