Question

Hyaluronic acid (HA).

The premise for adding HA to moisturisers is that aging skin is associated with loss of skin moisture. The key molecule involved in skin moisture is hyaluronic acid. 1g of HA can attach to and hold approximately 6L of water. HA is composed of repeating disaccharides (two sugar molecules), D-glucuronic acid and N-acetyl-D-glucosamine. Depending on the length of the repeating disaccharides, the molecule can be low molecular weight (short chains) or high molecular weight (long chains). Within the human body, HA has a half-life of only 3-5 minutes in the blood, less than a day in the skin and 1 to 3 weeks in cartilage.

We are looking at Hyaluronic acid (in a biology pov). But they have not given us information to answer thw following:

• What properties influence whether a substrate will penetrate the stratum corneum?
• Which properties of HA would hinder its passage through the stratum corneum?
• Which properties of HA would help its passage through the stratum corneum?
• How far does HA applied to the surface of the skin penetrate the epidermis or dermis?

If any expert know any information regarding the answer to these questions please help. Thankk youuu :)

Answer 1