Chitosan Nanowhisker-Coated Cellulose Microbeads for pH-Triggered Release of Vitamin C

Chitosan nanowhisker (CSW)-coated cellulose beads were developed as a pH-responsive drug delivery system optimized for topical skin applications to improve the stability and controlled release of vitamin C. Vitamin C is a well-known antioxidant used in skincare formulations, but exhibits limited stability and poor skin permeability owing to its high hydrophilicity and sensitivity to environmental pH. To address these limitations, porous cellulose beads were fabricated by membrane emulsification followed by deacetylation, yielding a high surface area that facilitated efficient vitamin C encapsulation. Coating these with CSW improved the oxidative stability and imparted pH-responsive release, with cumulative release reaching 20.78 % at pH 5.5 (healthy skin) and only 12.73 % at pH 7.4, which may help moderate diffusion and potentially reduce irritation under inflamed conditions. In addition, the coated beads exhibited antibacterial activity against Staphylococcus aureus, achieving an 11.1 % reduction in bacterial growth (OD₆₀₀), which was attributed to the intrinsic antimicrobial properties of chitosan. This cellulose-based delivery system demonstrates strong potential for cosmeceutical applications owing to its biocompatibility, effective encapsulation, controlled pH-responsive release, and multifunctional attributes suitable for various skin conditions.