Somewhere along the way, skincare adopted a rather simple rule:
Smaller molecules penetrate deeper. Deeper must be better.
But better for what?
If you're trying to deliver a pharmaceutical through the skin, penetration can be enormously important.
But if you're trying to hydrate the skin, perhaps we've been asking the wrong question.
The surface of your skin isn't an annoying wall that every useful ingredient needs to get through. It is the very barrier we're trying to keep hydrated, supple and functioning.
So sometimes, staying put is the point.
Large water-binding polymers can remain within and around the outer layers of skin, creating a hydrated film and helping retain water where it is being lost.
And there is another problem with the idea that there must be one perfect molecular size.
Biological polymers don't necessarily come as identical little units marching in formation. They can exist as a distribution of molecular sizes — known as polydispersity.
That matters.
Different chain lengths have different physical behaviours. Smaller fractions may move further into the outer skin. Larger chains may remain closer to the surface, where they can bind water and form a hydrated network.
Perhaps the interesting question in skincare isn't:
“How small can we make the molecule?”
Perhaps it is:
“Can we create the right molecular landscape for the skin?”
That is particularly interesting to us because Phyaluronic® is not simply another small molecule designed to disappear through the skin.
It is a large sulfated marine polysaccharide with a distribution of molecular sizes — and we are increasingly interested not just in how much water it can bind, but where those different molecules reside, how long they remain there, and what that means for maintaining hydration at the skin boundary.
Because when it comes to hydration, penetration isn't necessarily the destination.
Retention might be.
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