Tuning the Microstructures of Electrospray Multicore Alginate Microspheres for the Enhanced Delivery of Astaxanthin

Multicore alginate microspheres (MCPs) have been demonstrated as promising carriers for bioactive substances. Herein, the influence of the size of the inner core on the bioaccessibility of astaxanthin (AST) was investigated using both in vitro and in vivo methods. MCPs with different inner core sizes were fabricated in which the oil-in-water emulsion with different oil droplet sizes was embedded in alginate microspheres (AST@MCPs) via the electrospray technology. The AST@MCPs appeared as a uniform sphere with an average size of 300 μm. The AST encapsulation efficiency in the AST@MCPs was determined to be more than 68%, which was independent of the inner core size. The bioaccessibility of AST increased from 38.3 to 83.2% as the size of the inner core decreased. Furthermore, the anti-inflammatory activity of AST@MCPs after in vitro simulated digestion was evaluated by LPS-induced RAW264.7 cells. The results suggested that AST@MCPs with a smaller inner core size exhibited a stronger anti-inflammatory activity, which further proved the results obtained from in vitro simulated digestion. As expected, the oral administration of AST@MCPs significantly mitigated colitis symptoms in DSS-induced ulcerative colitis mice. Compared with AST@MCPs with larger inner cores, AST@MCPs with smaller inner cores reflect stronger anti-inflammatory activity in vivo. These results suggested that the bioaccessibility of AST in MCPs increased significantly with the decrease in the inner core size, which may be attributed to the rapid formation of micelles in the intestine. This work provides a simple and efficient strategy to prepare microspheres for the enhanced delivery of AST, which has important implications for the design of health-promoting foods.