A fusogenic liposome composition for delivering a
liposome-entrapped compound into the cytoplasm of a target cell is
described. The liposomes have an outer surface coating of
chemically releasable hydrophilic polymer chains which shield
hydrophobic polymers on the liposome outer surface. Release of the
hydrophilic polymer chains exposes the hydrophobic polymers for
interaction with outer cell membranes of the target cells to
promote fusion of the liposome with the target cells. Also
disclosed is a method for using the composition to deliver a
compound to target cells, and a method for selecting suitable
hydrophobic polymers for use in the composition.