How is hydrolysed hyaluronic acid encapsulated in certain skincare products?

The hyaluronic acid is a polysaccharide naturally present in the extracellular matrix of connective tissues. Essential for skin hydration, it plays a key role in the processes of healing and cellular regeneration. Due to its interesting skin properties, the hyaluronic acid is included in the composition of many cosmetic products, in various forms. Obtained by hydrolysis of high molecular weight hyaluronic acid (raw form), hydrolysed hyaluronic acid is composed of relatively small fragments. It is often encapsulated in a matrix before being integrated into a cosmetic product, in order to improve its stability, bioavailability and effectiveness.

In cosmetics, hydrolysed hyaluronic acid is typically encapsulated within liposomes. These are spherical vesicles composed of phospholipid bilayers, similar to human cellular membranes. The hydrophilic part of the liposomes, with which hyaluronic acid has an affinity, is oriented inwards and protects the active ingredient from enzymatic degradation. Liposomes also enhance the penetration ability of hyaluronic acid due to their capacity to merge with cellular membranes. Occasionally, hyaluronic acid is encapsulated within niosomes, which are analogues of liposomes produced from non-ionic surfactants, but this is less common. The encapsulation within liposomes is carried out in the following manner:

• Liposome formation.

  There are various methods for forming liposomes from lipids, such as reverse phase evaporation, injection, electroformation, microfluidics, thin layer hydration, freeze-drying of double emulsions, membrane extrusion... These techniques all involve four fundamental steps: the drying of a lipid mixture from an organic solvent, the dispersion of lipids in an aqueous medium, the separation and purification of the formed liposomes, and the analysis of the final product.

• Preparation of liposomal hyaluronic acid gel.

  The encapsulation of hyaluronic acid within liposomes is a relatively straightforward process. The active ingredient is first dissolved in a buffer solution with a pH of 7.4 before being added to the liposome suspension. The mixture is then homogenised using a vortex for a few minutes. The liposomes in which the hyaluronic acid has been encapsulated are then stored at 4°C, a temperature that allows them to remain stable.

• Integration into a cosmetic formulation.

  The encapsulated hyaluronic acid is then incorporated into a cosmetic product such as a cream, serum or lotion. The aim is to create a uniform formulation that gradually releases the hyaluronic acid in a hydrolysed form, thereby maximising its benefits for the skin and reducing the risk of irritation.