Membrane Biophysics (To be updated)

One of the most important structural elements in all living cells is the biological membrane. Not only does it partition, compartmentalise and organise the complex hierarchy of intracellular biochemical environments in the cells, but it also plays a vital role in cellular signaling and trafficking. Furthermore, synthetic lipid membranes increasingly find applications as novel materials with tunable properties.

Understanding biomembranes is generally a very difficult task. Self-assembled lipid structures can adopt an astonishing range of complex shapes and structures in 1, 2 or 3 dimensions, and cover length scales ranging from nanometres to microns. In some cases, the molecular identity of the lipids and the membrane proteins is paramount. In other cases, membrane elasticity and/or hydrodynamic interactions are the key physics. To this end, no single technique is suitable and we use a combination of analytical and computational techniques to provide insights into these problems.

Vesicles in Contact With Multiple Aqueous Phases

One topic which has attracted our interests in recent years is membranes and vesicles in contact with several aqueous phases. This novel system exhibits a number of interesting phenomena, including wetting transition, budding and tubular formation. This work is a collaboration with Y. Liu (Chinese Academy of Sciences), R. Lipowsky and R. Dimova (Max Planck Institute of Colloids and Interfaces). Below is a movie of a vesicle containing phase separating polymer solutions: by increasing the osmotic pressure outside the vesicle, water comes out of the vesicle and phase separation occurs.

Morphologies of Vesicles

We are developing novel techniques for computing the shapes of lipid vesicles. What separates our techniques from previously published results is our ability to compute not only the minima, but also the transition pathways and energy barriers between any two minima. This allows us to obtain and visualise a global view of the free energy landscapes. The method can be generalised to study other membrane-based structures.