Calcium alginate microcapsules loaded with vanillin–chitosan complexes for improving biosafety and bioavailability

Abstract

Despite the promising applications of zinc-loaded microcapsules, their facile and controllable preparation is compulsory, especially for biosafety and high bioavailability. Herein, calcium alginate microcapsules loaded with vanillin–chitosan Schiff base zinc (VCSB-Zn(II)@CA) were successfully prepared via exogenous emulsification for continuous and sustained release of Zn²⁺. These microcapsules were characterized using FT-IR, SEM, and TGA analyses. Multi-factor (MF) orthogonal experiment results revealed the optimum preparation conditions as 50 g L⁻¹ of CaCl₂, 1.5% of Span 80 in the oil phase, 20 g L⁻¹ of SA, and 1/75 (g g⁻¹) vanillin–chitosan Schiff base zinc (VCSB-Zn(II)) to SA ratio. Accordingly, an encapsulation efficiency (EE) of about 65.21% was achieved. In comparison to chitosan–Zn(II) (Chs-Zn(II)), VCSB-Zn(II) released Zn²⁺ only in a simulated gastric fluid environment, and the VCSB-Zn(II)@CA microcapsule showed good continuity in the whole release process. The cumulative release rate (R_i) of VCSB-Zn(II) and VCSB-Zn(II)@CA was close and much higher than that of Chs-Zn(II), which were 82.81%, 79.15%, and 57.33%, respectively. The release curve met the first-order and the Korsmeyer–Peppas model, which followed the Fick diffusion mechanism. In future, this Zn²⁺ sustained release system could offer more efficient applications for trace element supplementation to human beings and animals.