Understanding Why Alcohol Is Such A Good Disinfectant/Antivirus.

We’d have to look back at the fundamentals of protein chemistry to understand what’s going on.

Both alcohol-based and non-alcohol based hand sanitizers have been ubiquitous throughout the past few years. When the COVID-19 pandemic was raging in full force in 2020, The Wall Street Journal reported that sales of hand sanitizers had jumped by 600% during that period. Demand for these products got so out of hand in the early months of the pandemic that rationing was necessary and price hikes were inevitable.

And as we know, alcohol is one of the most commonly used ingredients in hand sanitisers. When we go for an injection at a hospital or a clinic, our skin is swabbed with 70% iso-propyl alcohol (IPA) prior to the needle piercing our skin — we need to get rid of any potential surface bacterial contaminants and viruses before we get that injection. This same IPA is present in most alcohol-based hand sanitizers too. But why is it that useful?

We’d have to look at bacterial cell structures first.

A bacterial cell is a living microorganism cell. These cells tend to have lipid bilayer membranes that encompass the functioning factories and mechanisms that keep the cell alive and productive.

This lipid bilayer consists of multiple phospholipid molecules that have a hydrophilic (water-loving) head and a hydrophobic (water-hating) tail. The hydrophilic head is the portion of the bilayer that comes into contact with the extracellular fluid — in the body, that extracellular fluid tends to be blood.

Another hydrophilic head comes into contact with the hydrophilic cytoplasm, which houses the cell’s factories and operating mechanisms. The lipid bilayer protects the cytoplasm from the extracellular fluid, and within the bilayer are embedded proteins that function as transporters of materials across the bilayer.

The GLUT4 transporter proteins, for instance, are proteins that rely on the signalling from insulin to commence transporting glucose from the blood into the cytoplasm, which is then used for energy generation within the cell. They are embedded within the lipid bilayer itself.

The glucose itself does not come into contact with the lipid bilayer — the GLUT4 proteins are transporting channels that regulate the flow of glucose into the cell, as in the glucose flows through the GLUT4 protein channel into the cell. In that way, when the cell has taken in sufficient glucose, it can then send a signal to the GLUT4 proteins to stop any more glucose from entering the cell. We don’t want the cell to overdose on glucose, after all. That isn’t good for the cell.

Unfortunately, this lipid bilayer can be pretty fragile. It can be easily disrupted and destroyed by exposure to other chemicals, and when this lipid bilayer is disrupted, the cell’s cytoplasm would be exposed to the extracellular fluid and damage the cytoplasm.

A cell with a damaged cytoplasm can be considered dead for all practical purposes — after all, the proteins that are embedded within the bilayer will be structurally disturbed once the bilayer is perturbed.

And when the proteins in the bilayer are structurally disturbed, it may end up losing the biochemical functions that they once used to possess, which results in an overall loss of cellular activity.

What if the damage got all the way to the DNA polymerase enzymes that facilitate cell replication? This cell isn’t going to be able to reproduce.

Cholesterol, surprisingly, acts as a protector of the lipid bilayer. By adding cholesterol to a lipid bilayer, the lipid bilayer faces a rearrangement in its physical structure such that their overall permeability is reduced. This reduced permeability reduces access to most damaging chemicals, which preserves the lifespan of the lipid bilayer.

We can see that cholesterol is beneficial to the lifespan and the survivability of a cell, and that is why it isn’t in our best interest to reduce our blood cholesterol levels down to an absolute minimum.

We need cholesterol around in our blood for providing adequate protection to the cells in our blood, but an accumulation of cholesterol in the blood can easily lead to issues with oxidative stress and cell apoptosis.

Simply put, high blood cholesterol isn’t that great, and what we need more is a balance between the input and output of cholesterol from our body to keep our cells optimally healthy.

But even cholesterol cannot protect the lipid bilayer from harsh, concentrated chemicals, and that’s when hand sanitizers and alcohol swabs come in.

At high alcohol concentrations, bilayer stability is affected and the permeability of the bilayer increases — making the cell more susceptible to chemical attack.

When we can sufficiently perturb the bilayer of a cell, we can kill it off.

Hence a good wipedown with concentrated alcohol can do the trick of being a good antibacterial agent.

While a virus does not contain a cytoplasm, it has a capsid that contains the precious genetic information of the virus within that “envelope”… and of course, the capsid is also protected by a lipid bilayer.

Concentrated alcohols can also disrupt the lipid bilayer of a virus particle and deactivate it.

And that’s the whole reason why there was that burgeoning demand for hand sanitizers. Even now, as we are at the tail end of the pandemic, many people still rely on hand sanitizers when they go out and about.

Of course, alcohol isn’t the ONLY disruptor of the lipid bilayer out there. There do exist other non-alcohol based lipid bilayer disruptors such as benzalkonium chloride. The main consideration of the hand sanitizer is to disrupt the lipid bilayers of different microorganisms out there!

And that’s how a hand sanitiser can be good for killing off unwanted bacterial and viral particles that exist on just about any surface, unseen to the naked eye.

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