 There is, of course, another particular virus that we can't help to mention right now, or rather not so much the virus, but this. Do you know what this is? This is the sequence that's going to save a fair share of us this year. This is the mRNA sequence of the Pfizer-BioNTech mRNA vaccine against COVID-19. You can read the sequence. You might find that there is a little psi here. The reason for that, if we use uracil, it will actually set off our immune system that would target the mRNA itself. But by replacing U for pseudo-uridine, which is the psi, this is silent. It will not trigger the immune system, but just a minor detail. So we just now need to inject this in each and every cell in our body. Wait a second, that's going to be problematic. The RNA is very fragile, so I can't eat it either. And in fact, if I just inject it, it might very well end up in the fat or breakdown before it has time to reach the cells. So we need to find a way for this mRNA to be delivered to the right place. The way that is done in these vaccines is actually using lipids, this type of thing called LLNP lipid nanoparticle. We don't know exactly what the structures of lipid nanoparticles are yet. There's been a lot of trial and error and experiments to optimize their properties. But briefly, we have a bunch of lipids, a coat here, that solvates some cholesterol, other lipids, there are some surfactant proteins, there are maybe some lipids here that are pH dependent so that we deliver them to the right cells. And then there are some relatively large water cavities here, the blue parts maybe, where the mRNA itself, the long string, would be bound. And you saw in the previous slide, it's a fairly long string. So these are going to be large particles. They work well, so I wouldn't worry about taking it at all, but it's still fascinating that we have something so exceptionally important, we hardly know anything about the internal structure. That is of course because the mRNA vaccines was just a distant future possibility until a year ago. And I bet I even know that there are a fair number of pharmaceutical companies that are now spending a lot of time and research money on understanding and characterizing lipid nanoparticles as delivery mechanisms, primarily for mRNA vaccines, but potentially also for other drugs. Imagine if you could tailor a cancer drug so it's only delivered to the tumor cells and not anywhere else in the body. Super exciting research. I just wish that I had a structure I could show you, but that's going to be up to you to fix.