As a negatively charged lipid that can stably add negative charges to the surface
of vesicles without side effects, the carboxyl acid-type lipid of the following
general formula [1]:
##STR1##
[wherein R1, R2 and R3 represent substituents
of which one is represented by the following general formula [X]:
##STR2##
(wherein M is a hydrogen atom or monovalent cation, and m is an integer
of 1 to 5 that represents the methylene chain length), and the other two are chained
hydrocarbon groups; A1, A2 and A3 are the same
or different substituents selected from the group consisting of C(O)O, CONH or
NHCO; and n is an integer of 1 to 3 that represents the methylene chain length)
is provided.
