Evaluation of a Bile-Independent Vitamin D3 Nano-Microencapsulated Delivery System: Efficacy of Amphiphilic Modified Starch in Overcoming Absorption Barriers and Storage Instability

This study aimed to evaluate a novel nano-microencapsulated self-emulsifying delivery system designed to overcome the dual challenges of storage instability and bile-dependent absorption of vitamin D3. The system utilizes octenyl succinic anhydride (OSA)-modified starch as an amphiphilic wall material and medium‑chain triglycerides (MCT) as the carrier to encapsulate vitamin D3 into solid microcapsules. Performance was assessed through an accelerated stability test (40 ℃/75% RH, 6 months) and an in vitro dissolution study in bile-free simulated intestinal fluid. Results showed that the system maintained a vitamin D3 retention rate of 98.4% after accelerated aging, significantly higher than the 61.4% retention of a conventional corn-oil control. In the bile-free medium, cumulative release reached 96.2% within 60 minutes, with a burst release of 88.5% in the first 15 minutes, and the system spontaneously formed uniform nanomicelles with an average particle size of 168.5 nm. In conclusion, the nano-microencapsulated system effectively enhanced the oxidative stability of vitamin D3 through solid-state encapsulation and achieved efficient bile-independent release and absorption via self-emulsification. This offers a promising new strategy for vitamin D3 delivery in populations with compromised digestive function.