I have read that soap does not kill bacteria and viruses, but it rather removes them, that is, it strips them off the skin sort of speak by forming micelles around them, which are then rinsed off.

But isn't it more logical that soap forms liposomes for viruses instead of micelles to remove them.

  • $\begingroup$ @z1273 This question seems to focus on the chemical side so it is much better kept here. $\endgroup$
    – Jan
    Commented Feb 4, 2021 at 12:35

1 Answer 1


Whether a mixture of phospholipids/lipids/detergents form micelles or liposome is not dependent on the hydrophobic "payload" but on the nature of the amphiphilic molecules.

Detergents form micelles (and bubbles and antibubbles, when there is air around). The micelles are fairly small (radius similar to the length of the detergent), and they don't have space for an entire virus (diameter on the order of 100 nm) or bacteria (diameter on the order of 1000 nm). Detergents that form micelles are able, however, to solubilize membrane proteins (diameter on the order of 10 nm) by forming a band of detergents around the hydrophobic parts of membrane proteins.

Phospholipids mixed with cholesterol form lipid bilayers and liposomes (the latter by extrusion or sonification). The distinct behavior has to do with differently charged head groups and the number of hydrophobic tails.

Some bacteria are killed by detergents because they break down the cell membrane, integrating the phospholipids and cholesteral into the micelle. Viruses can't be killed because they are not alive. If they are surrounded by a lipid bilayer, the detergent can also break this down, rendering the genetic material inside harmless.

No matter whether bacteria and viruses are destroyed by the soap or not, the soap allows the water to wash the germs away, and they end up in the canalization (e.g. coronavirus genetic material in Boston) instead of in people's bodies.

  • $\begingroup$ May I ask you how exactly does a soap inactivate a virus? The lipid bilayer that surrounds viruses is polar from the outside. How does the soap get into the intermediate zone to fix to the lipids. And if and when it does attatch to the lipids how does it pry the bilipid layer? Does the water outside cause a tractional pull on the soap and that results in the lipids detaching? $\endgroup$
    – Mhkhm
    Commented Jan 26, 2021 at 4:28
  • $\begingroup$ @Mhkhm That is an intriguing follow-up question, ready to be posted. I would argue it is more interesting and of higher quality than the original question, but of course that is for the community to decide. $\endgroup$
    – Karsten
    Commented Jan 26, 2021 at 12:23

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