Synergistic stabilization of Pickering emulsions by agar-chitosan composite particles and their potential for improving the bioavailability of lipophilic simvastatin.
Du Lipeng L, Han Xinyu X, Zhang Xingtao X, Wu Xiao X et al.
Natural biopolymer-based Pickering emulsions have emerged as promising green delivery systems for lipophilic bioactives. Agar exhibits excessive hydrophilicity with poor amphiphilic balance. Chitosan has limited solubility at physiological pH and weak independent gelation capacity. Simvastatin is a widely used lipid-lowering drug with an oral bioavailability of only about 5% due to poor aqueous solubility and gastrointestinal instability. To address these critical gaps, agar-chitosan composite particles (AGCS) were fabricated via spray-drying to stabilize Pickering emulsions for simvastatin delivery. FT-IR confirmed that electrostatic and hydrogen bonding modulated composite particle amphiphilicity. This resulted in a 97.27° contact angle and reduced interfacial tension of 13.5 mN/m. The emulsions exhibited exceptional stability at pH greater than 5 and salt levels less than 150 mmol/L. They also retained structural integrity after heat treatment up to 100 °C. This stability arose from a dual mechanism involving a dense interfacial film and a self-assembled three-dimensional gel network. Rheological analysis revealed elastic-dominated behavior supporting a 95% encapsulation efficiency at 60% oil phase fraction. In vitro digestion demonstrated that composite emulsion gels protected simvastatin from gastric degradation while enhancing bioaccessibility to 33.5% compared to free simvastatin. This work elucidates the synergistic stabilization mechanism of agar-chitosan composite particles. These particles overcome the individual limitations of native polysaccharides. The findings highlight their potential as a green biocompatible carrier for lipophilic drug delivery in biomedicine and the food industry.