Liposomes as vehicles for transferring low molecular weight compounds into periwinkle protoplasts

The uptake of liposomal contents into Catharanthus roseus protoplasts has been quantitated. Hi.phest uptake was obtained from positively charged vesicles (1.09% of vesicle contents per 10(7) protoplasts) in the presence of 10% w/v polyethylene glycol 4000. Significant uptake was also observed from negatively charged vesicles (0.1% of vesicle contents per 10(7) protoplasts) in the presence of 25% polyethylene glycol 1540. The uptake of vesicle contents from negatively charged liposomes was confirmed by light microscopy after treatment of the protoplasts with liposomes loaded with the fluorescent dye 6-carboxyfluorescein. About 10% of the treated protoplasts exhibited intracellular fluorescence. No uptake from neutral liposomes was detected.