Liposomes as model cellular systems

Abstract

Liposomes are spherical structures composed of a phospholipid bilayer membrane that encapsulates an aqueous cavity. The diameter of a liposome ranges from tens of nanometers to tens of micrometers, and with its pliable membrane, it can be forced to flow in a microfluidic system in a manner that is reminiscent of a cell flowing through capillaries in the vasculatory system. For many years, our research has focused on defining new analytical applications for liposomes. In this chapter, we describe the use of liposomes as reagent delivery vessels that can be stimulated to release their contents as a function of temperature in a microfluidic system to initiate mixing and bio/chemical reaction. We also describe the use of microfluidic systems to automate the formation of liposomes. Using the simple principles of hydrodynamic focusing in microfluidics, we have demonstrated the ability to prepare very homogeneous populations of liposomes with encapsulated reagents that are suitable for a wide variety of analytical and biomedical applications.