Question: Hi Matt, I read on your profile that you like "zapping cells with lasers" , and I was wondering how you are able to zap them with lasers when they are so tiny you can't even see them unless you use a microscope.
I want to try that someday! It sound fun
This is a great question! I use two different machines that both zap cells with lasers. In both cases – the lasers actually stay still, only the cells move! The first machine is in fact a microscope, so even though the cells are tiny I can see them. The cells are stuck down on a glass slide so I just have to move the slide until it is above the laser beam.
The other machine is called a ‘flow cytometer’. Flow cytometers are pretty clever, because I can put all of my cells in a container, and the machine sucks them up into a stream of fluid. The fluid gets thinner and thinner, until eventually the cells are whizzing through the machine in single file. Like in the microscope, the lasers in this particular machine are not too dangerous – you wouldn’t want to look at them because they would damage your eyes – but they won’t burn or anything. But you can stick molecules onto your cells that absorb the laser light, and then they glow a different colour in a way that can be detected by the machine.
So I stick these glowing molecules onto some of the cells, and I run them all one at a time past 3 or 4 lasers which are turned on inside the machine. The cells fly through the laser beams, and if they have one of the molecules attached, they’ll glow a certain colour just as the laser hits them! There is a detector in the machine which knows if the cell was glowing or not. It can either tell you later, which is useful if you have already done an experiment. The glowing molecules may only stick to cells that were activated in the experiment, and this can tell you which ones! Or if you haven’t done an experiment yet, it can actually flick the cells with the molecules into a new container so you can then use them later.
This lets you pick out even just a single type of cell, out of a big mixture of lots. I’m studying one particular sort of white blood cell so this helps me get hold of some of those, even when I start from the huge blend of cells we have in our blood!