Optimization of Citrus aurantifolia peel extract encapsulation in alginate-gelatin hydrogel microbeads for antibacterial wound dressing applications

Abstract

The extract of Citrus aurantifolia peel has been encapsulated into alginate-gelatin-based microbeads using an external ionotropic gelation method to apply antibacterial wound dressings. Such variables, like the alginate-gelatin ratio, extract quantity, and CaCl2 cross-linkers, were optimized to produce a good yield, well-distributed size, and encapsulation efficiency. Antibacterial efficacy was tested against both S. aureus and E. coli. Optimal microbead characteristics were obtained at alginate:gelatin concentration ratio of 1.75 %:0.25 % (w/v), with 15 mg of extract and a 2 % CaCl2 cross-linker. These conditions resulted in the microbeads with 82.94 ± 1.056 % yield, particle sizes between 1.080–1.244 µm, and encapsulation efficiency of 79.127 ± 0.186 %. The microbeads exhibited an almost spherical morphology with a slightly rough surface. The extract release mechanism out of the microbeads was governed by both diffusion and erosion of the shells following the Korsmeyer-Peppas kinetic model (k = 1.014 ± 0.007/min). Upon immobilizing the microbeads on gauze, an add-on percentage of 73.98 % was observed. Moreover, the gauze-immobilized microbeads inhibited S. aureus and E. coli growth with inhibition zones of 11±1.48 and 12.56±4.89 mm, respectively. In conclusion, the antibacterial alginate-gelatin-based microbeads have demonstrated optimal characteristics and exhibited effective inhibition against S. aureus and E. coli, showcasing their potential as antibacterial wound dressings.