Bilayers are widely studied and critically important to a wide range of biological systems, a full understanding of which requires a deeper understanding of the interactions that occur within the bilayer. As interactions between lipids and proteins underpin the functions of the cell membrane and how proteins removed from a cell membrane behave. Here I present two different methods using a bottom up approach
that can be used to investigate the interactions that occur within a bilayer, both natural, lipid, and artificial, polymer.
A bottom-up approach to understanding the mammalian cell is to develop an artificial cell using either lipids or amphiphilic polymers to make the bilayer membrane, but keeping proteins stable in these membranes has proven difficult. Here, I show that the key to stabilising proteins within the membrane is the thickness of the membrane, and through the minimisation of the hydrophobic mismatch between the protein and the bilayer, the relative activity of a light-harvesting complex in a polymer membrane
can be significantly improved by an order of magnitude. When this is combined with the inherent stability of polymer vesicles (polymersomes), a system that remains stable for several months has been developed using low (around 1000Da) molecular weight polymers.
This is, however, only one aspect of the complex environment that makes up a cell membrane. The formation of membrane rafts is thought to be driven by the desire to minimise the hydrophobic mismatch between the lipid bilayer and proteins. Using Fluorescence Lifetime Imaging (FLIM) microscopy, I have been able to image micron-sized lipid domains and distinguish between liquid ordered and liquid disordered domains from the fluorescent signal from Texas Red, NBD and DI-4-ANEPPDHQ. Providing
a toolkit that can be used in future investigations.
