Surface modification of sodium hyaluronate with dopamine to enhance emulsifying capacity and application performance

Hyaluronic acid (HA) is a mucopolysaccharide alternately linked by glucuronic acid and n-Acetylglucosamine as disaccharide units. This study prepared HA derivative (DA-HA) by modifying sodium hyaluronate with dopamine (DA). DA-HA had unique surface activity. By optimizing the reaction conditions systematically, DA-HA could prepare the emulsion with uniform droplets successfully. When n (COOH) /n (EDC) /n (NHS) was 1/2/4, n (HA) /n (DA) was 1/5, the reaction pH was 5.5, and the molecular weight of HA was 1350 KDa, the emulsion particles were relatively uniform. The chemical structure of DA-HA was characterized, and the results showed that DA was grafted on the HA chain through the amide bond. In addition, the effect of formula composition on the emulsifying performance of DA-HA was studied. The particle size of emulsion decreased as the concentration of DA-HA increased. When the oil-water ratio was 4/6 or 5/5, the emulsion droplets were small and uniform. When the aqueous phase was in an acidic or weakly alkaline condition, the particle size of the emulsion was smaller. The introduction of high salinity will destroy the stability of the emulsion. Meanwhile, DA-HA also had good moisturizing property and biosafety, which greatly expanded the application of HA in cosmetics.

Graphical abstract