Excellent 39-part twat thread (with some comments) that explains why and how soap kills viruses.
https://twitter.com/PalliThordarson/status/1236549305189597189
Palli Thordarson @PalliThordarson
1/25 Part 1 - Why does soap work so well on the SARS-CoV-2, the coronavirus and indeed most viruses? Because it is a self-assembled nanoparticle in which the weakest link is the lipid (fatty) bilayer. A two part thread about soap, viruses and supramolecular chemistry #COVID19
2/25 The soap dissolves the fat membrane and the virus falls apart like a house of cards and "dies", or rather, we should say it becomes inactive as viruses aren’t really alive. Viruses can be active outside the body for hours, even days.
3/25 Disinfectants, or liquids, wipes, gels and creams containing alcohol (and soap) have a similar effects but are not really quite as good as normal soap. Apart from the alcohol and soap, the “antibacterial agents” in these products don't affect the virus structure much at all.
4/25 Consequently, many antibacterial products are basically just an expensive version of soap in terms of how they act on viruses. Soap is the best but alcohol wipes are good when soap is not practical or handy (e.g. office receptions).
5/25 But why exactly is soap so good? To explain that, I will take you through a bit of a journey through supramolecular #chemistry, nanoscience and virology. I try to explain this in generic terms as much as possible, which means leaving some specialist chemistry terms out.
6/25 I point out to that while I am expert in supramolecular chemistry and the assembly of nanoparticles, I am not a virologists. The image with the first tweet is from an excellent post here which is dense with good virology info:
7/25 I have always been fascinated by viruses as I see them as one of them most spectacular examples of how supramolecular chemistry and nanoscience can converge. Most viruses consist of three key building blocks: RNA, proteins and lipids.
8/25 The RNA is the viral genetic material -it is very similar to DNA. The proteins have several roles including breaking into the target cell, assist with virus replication and basically to be a key building block (like a brick in a house) in the whole virus structure.
9/25 The lipids then form a coat around the virus, both for protection and to assist with its spread and cellular invasion. The RNA, proteins and lipids self-assemble to form the virus. Critically, there are no strong “covalent” bonds holding these units together.
10/25 Instead the viral self-assembly is based on weak “non-covalent” interactions between the proteins, RNA and lipids. Together these act together like a Velcro so it is very hard to break up the self-assembled viral particle. Still, we can do it (e.g. with soap!).
11/25 Most viruses, including the coronavirus, are between 50-200 nanometers – so they are truly nanoparticles. Nanoparticles have complex interactions with surfaces they are on. Same with viruses. Skin, steel, timber, fabric, paint and porcelain are very different surfaces.
12/25 When a virus invades a cell, the RNA “hijacks” the cellular machinery like a computer virus (!) and forces the cell to start to makes a lot of fresh copies of its own RNA and the various proteins that make up the virus.
13/25 These new RNA and protein molecules, self-assemble with lipids (usually readily present in the cell) to form new copies of the virus. That is, the virus does not photocopy itself, it makes copies of the building blocks which then self-assemble into new viruses!
14/25 All those new viruses eventually overwhelm the cell and it dies/explodes releasing viruses which then go on to infect more cells. In the lungs, some of these viruses end up in the airways and the mucous membranes surrounding these.
15/25 When you cough, or especially when you sneeze, tiny droplets from the airways can fly up to 10 meters (30 ft)! The larger ones are thought to be main coronavirus carriers and they can go at least 2 m (7 ft). Thus – cover your coughs & sneezes people!
16/25 These tiny droplets end on surfaces and often dry out quickly. But the viruses are still active! What happens next is all about supramolecular chemistry and how self-assembled nanoparticles (like the viruses) interact with their environment!
17/25 Now it is time to introduce a powerful supramolecular chemistry concept that effectively says: similar molecules appear to interact more strongly with each other than dissimilar ones. Wood, fabric and not to mention skin interact fairly strongly with viruses.
18/25 Contrast this with steel, porcelain and at least some plastics, e.g. teflon. The surface structure also matter – the flatter the surface the less the virus will “stick” to the surface. Rougher surfaces can actually pull the virus apart.
[Moar at website]