Nano-technology.

The term liposomes (i.e. lipid body) is derived on the basis of names of sub cellular particles like lysosome and ribosomes. It is a sphere vesicle of lipid bilayers enclosing an aqueous compartment. The lipid most commonly used is phospholipids. Because of their availability in various sizes, ability to incorporate both water as well as oil soluble drugs, their inertness and their ability to protect labile drugs, liposomes are versatile carriers for parenteral drug delivery system. Liposomes have been realized as extremely useful carrier systems, additives and tools in various scientific domains. Liposomes over the years have been investigated as the major drug delivery systems due to their flexibility to be tailored for varied desirable purposes. They can be administrated parenterally, topically, by inhalation and possibly by other routes of administration, but the current products are administrated parenterally. Fusogenic liposomes are specially engineered liposomes that fuse and merge with cell membranes and directly introduce molecules (entrapped or anchored) into cytoplasm thus avoiding the route followed by conventional liposonmes, i.e., internalization via endocytic compartments into lysosomes. The fusogenic liposomes mimic the way by which several viruses (HIV, Sendai virus) bind and merge with cell membranes at neutral pH and subsequently release their genome into the cytoplasm.