Modification of liposomes by addition of HCO60. II. Encapsulation of doxorubicin into liposomes containing HCO60.

The efficiency of encapsulation of doxorubicin (DOX) into liposomes containing HCO60 was studied. Empty egg phosphatidylcholine (PC) liposomes containing various amounts of HCO60 were passed through a polycarbonate membrane filter (0.1 micron). Closed vesicles were formed even with liposomes containing 90 wt% HCO60. DOX was encapsulated efficiently (more than 1 mg DOX/8 mg lipids) using a pH-gradient method. HCO60 accelerated the leakage of DOX from liposomes into phosphate buffer at temperatures above 25 degrees C. HCO60 suppressed the leakage of DOX from egg PC/cholesterol (7/3, w/w) liposomes into phosphate buffer containing 50% fetal bovine serum (FBS). Studies on the interaction between liposomes and serum components using zeta potential and turbidity suggest that HCO60 prevents the liposomes from interacting with serum components.