(W/O/W) Double Emulsions-Filled Chitosan Hydrogel Beads for Topical Application

The aim of this study was to develop double emulsions-filled chitosan hydrogel beads for topical application and to elucidate their skin penetration behavior. Double emulsions were prepared by a two-step emulsification method, and double emulsions-filled chitosan hydrogel beads were prepared by the extrusion method. The structure, stability, and skin penetration behavior were investigated. The results of yield efficiency (above 80%) and microstructure observation confirmed the feasibility of the preparation method. After loading the hydrophilic active ingredients (vitamin C) into this system, the retention ratio after storage for 6 weeks increased by 77.6%. Furthermore, hydrogel beads could promote the permeation of hydrophilic active ingredients loaded in double emulsions. When the concentration of chitosan was 3% (w/v), the permeation coefficient of vitamin C from hydrogel beads exhibited an increase (1.7-fold) compared with double emulsions. This system could affect the orderliness of lipid structures in the stratum corneum. In addition, the results indicated that this system could be used for the topical delivery of hydrophobic active ingredients (quercetin) as well. This is the first report of chitosan bead stabilization of W/O/W emulsions, yielding a 2.6-fold increase in skin uptake of hydrophilic actives.