Kathryn A. Whitehead

For over five decades, scientists and engineers like myself have been creating the shipping materials for nucleic acid drugs like DNA and RNA.

Through trial and error, we've created packages that deliver intact faces to the wrong address, that deliver to the right address but with a broken face, packages that get ripped apart by attacking dogs, and packages that throw out the mail carriers back.

It's taken many years to get the science right.

Let me tell you the result.

These tiny balls of fat

that we call lipid nanoparticles.

Let me tell you what they are and how they work.

So first of all, nano just means really, really small.

Think of how small a person is compared to the diameter of the Earth.

That's how small a nanoparticle is compared to the person.

These nanoparticles are made up of several fatty molecules called lipids.

Fat is an awesome packing material, nice and bouncy.

Interestingly, our cells are also surrounded by fat to keep them flexible and protected.

Years ago, scientists had the idea to create lipid nanoparticles that would act like a Trojan horse.

Because the lipids in the nanoparticle look similar to the membranes that surround our cells, the cells are willing to bring the nanoparticle inside, and that's when the mRNA is released into the cell.

So what exactly are the lipids in these nanoparticles?

There are four ingredients in addition to the mRNA, and I'll tell you about each one.

First, there's a lipid called a phospholipid.

This is the primary ingredient in our cell membranes, which are the walls of fat that separate the insides of our cells from everything that surrounds them.

Phospholipids have a head that likes water,