Environmentally-Sensitive Vesicles for Controlled Drug Delivery

Abstract

The potential uses of phospholipid vesicles in drug delivery have been widely discussed. The present chapter summarizes work from this laboratory on the preparation of lipid vesicles that release their contents in response to specific chemical or physical stimuli. Contributions to this area from other laboratories may be found in references 15-21. The unifying theme of our work has been the use of environmentally sensitive polyelectrolytes to control the structure and permeability of the phospholipid vesicle membrane. In particular, we have found that the large changes in solvation and conformation that accompany the titration of hydrophobic poly(carboxylic acid)s can be exploited to effect phospholipid reorganization from vesicular to micellar form, as illustrated in Scheme I. This idea has been elaborated, as described below, to prepare phospholipid vesicles that respond to changes in pH, temperature or glucose concentration.