Sustainable Poly (Methacrylic Acid)/Nanocellulose Hydrogel for Controlled Simultaneous Release of Active Substances for Skin Protection.

Hydrogels based on poly (methacrylic acid), carboxymethyl cellulose, and nanocellulose fibers were successfully synthesized, characterized, and tested as topical carriers for the controlled release of hydrophobic resveratrol and hydrophilic acetyl glucosamine, active substances used in skin protection. Carrier composition was confirmed by Fourier-transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) revealed the pore size variations with alterations in the neutralization degree of methacrylic acid and changes in the pore-wall roughness caused by different mass fractions of nanocellulose. The neutralization degree of methacrylic acid had a substantial impact on the swelling behaviour, while only a slight change in swelling was caused by various contents of nanocellulose in hydrogels. Mechanical properties of the hydrogels accessed by compressive strength measurement at various percentages of strain were improved by the addition of nanocellulose. Hydrogels containing 0.5% nanocellulose achieved the highest compressive strength. The neutralization of methacrylic acid reduced the mechanical properties. Hydrogels with optimal properties showed outstanding potential in encapsulation, and controlled the simultaneous release of resveratrol and N-acetyl glucosamine. The different nature of the active compounds, however, affected the release kinetics and mechanism, as confirmed by the Korsmeyer-Peppas model.