SILANIZED-HA: FROM SYNTHESIS TO BIOMEDICAL APPLICATIONS
Camille KEÏTA*, Léa MESSAGER, Marianne LAFONT, Pierre WEISS, Anne-Laure GAUDRY
Hyaluronic acid (HA), the most famous glycosaminoglycan of the extracellular matrix, is also an incredible polymer. Thanks to its very wide range of molecular weight, from 103 to 107 Da (Daltons), HA presents versatile viscoelastic properties which make it suitable for various applications in many therapeutic fields such as viscosupplementation, ophthalmic surgery and aesthetic medicine, but also, increasingly, tissue engineering and regenerative medicine.
Despite the strong potential for using native HA in these fields, its viscoelastic properties are not sufficient to provide long-lasting effect (due to its natural enzymatic degradability) and to create versatile scaffolds. To improve and modulate the mechanical properties of the native structure, many crosslinking strategies have been developed over the years to design adjustable scaffolds.
One of them relies on the chemical grafting of silicon alkoxide groups onto the polymer backbone. This modification gives the opportunity to design hybrid organic-inorganic materials, which have already shown very promising assets for tissue engineering. Silanized functions undergo a reversible sol-gel transition in physiological conditions, leveraging the reversible self-condensation of silanol moieties into siloxanes bonds at neutral pH and resulting in the formation of a crosslinked polymeric three-dimensional network. By changing the modified HA molecular weight, the grafting rate and/or the concentration, the properties of the hydrogels are totally tunable, which pave the way to mimic an infinity of natural tissues, from bone to skin.
To tune the swelling and degradability properties of silanized HA, Si grafting has also been applied to Hydroxypropylmethylcellulose (HPMC), a biocompatible but not biodegradable polymer. Thus, combining the two derivatives offers the breakthrough possibility to develop a third generation of hydrogels, with totally adjustable rheological and mechanical features and degradation kinetics relevant for tissue reconstruction.