Hyaluronan

## General Information (more on wikipidia)

Species Molecular Weight (g/mol) Density (g/L) Radius (m) Reference
HA 500kD D R [1]

Hyaluronan (also called hyaluronic acid or hyaluronate) is a non-sulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. It is one of the chief components of the extracellular matrix, contributes significantly to cell proliferation and migration, and may also be involved in the progression of some malignant tumors. The average 70 kg man has roughly 15 grams of hyaluronan in his body, one third of which is turned over (degraded and synthesised) every day.

Hyaluronan is an important component of articular cartilage, where it is present as a coat around each cell (chondrocyte). When aggrecan monomers bind to hyaluronan in the presence of link protein, large highly negatively charged aggregates form. These aggregates imbibe water and are responsible for the resilience of cartilage (its resistance to compression). The molecular weight (size) of hyaluronan in cartilage decreases with age, but the amount increases.

Hyaluronan is also a major component of skin, where it is involved in tissue repair. When skin is excessively exposed to UVB rays, it becomes inflamed (sunburn) and the cells in the dermis stop producing as much hyaluronan and increase the rate of its degradation. Hyaluronan degradation products also accumulate in the skin after UV exposure.

## Diffusion of HA in a Aqueous HA matrix:

• Alone at 25 degrees: $D~= 4.5 \times 10^{-12}\ m^{2}/s$ [1]
Bibliography
1. The Journal of Chemical Physics, Vol. 121, No. 21, pp. 10787–10793, 1 December 2004 : Akiko Masuda and Kiminori Ushida