Origins of cellular life
Life as we know it is cellular life. Each cell has a cell membrane that not only protects the contents of the cell, but also controls the flux of nutrients, grows, divides, and in some cases, generates motility. Although the membrane itself owes its structure to phospholipids, most of the functions are carried out by proteins. This then begs the question of how cells performed all of these functions, prior to the evolution of all of these proteins.
We are interested in reproducing the basic functions of a cell membrane with the simplest, most primitive ingredients available. By working on these model primitive cells , we hope to gather insight into how cellular life may have started on early Earth, and the biophysical properties of bilayer membranes.
Here is an overview of what some people are doing in the field of protocell research.
How did primitive cells divide without any protein division machinery?
What roles can peptides and mineral particles play in primitive life?
Understanding colloidal interactions with digital holographic microscopy
One of the luxuries of working with soft matter is that some of the most important building blocks -- colloidal particles, cells, droplets -- are visible under the microscope. This is an incredible privilege because it makes the interpretation of the results more straightforward and enables better mechanistic insight.
We are interested in tracking their motion to give us insight into their interactions and behaviours.
We use a fast, 3D imaging technique called digital holographic microscopy (DHM) to glean quantitative information from our microscopy observations. In its simplest form, DHM uses a collimated coherent beam (e.g. laser or LED) in lieu of a white-light source and instead of a regular image, a hologram is captured on-camera. The interference fringes in the holograms contain information about the distance and orientation of the object, information that we can extract computationally.
It's difficult to imaging moving objects under a microscope because they go out-of-focus. In DHM out-of-focus objects have fringes which in turn can be used to gain insight into their 3D position.
As an object moves in the imaging plane, so does the centre of the interference pattern. As an object moves in and out of focus, the size and shape of the hologram fringes change.
DHM has ~2nm precision in all three dimensions
DHM can be used to track the motion of microorganisms (top), and the nanoscale-features of the interactions between colloidal particles and oil-water interfaces (bottom).