One-step assembly of astaxanthin-loaded probiotic-derived extracellular vesicles: a strategy for enhancing absorption and alleviating oxidative stress.

UNLABELLED: Improving the stability and intestinal absorption of antioxidants is a prerequisite for exerting their functional activities. Herein, astaxanthin (AXT)-loaded Lactobacillus rhamnosus GG-derived extracellular vesicles (EVs) (AXT@EVs) were prepared using ultracentrifugation combined with four loading strategies, including ultrasonication, co-incubation, freeze-thaw cycles, and extrusion. Among these methods, AXT@EVs prepared by ultrasonication exhibited the highest encapsulation efficiency. When the mass ratio of AXT to EVs was 1:10, the encapsulation efficiency reached approximately 72.93% and the retention rate remained 98.09% after storage at -80 °C for 90 days. EVs could resist structural damage under harsh environmental conditions, thereby significantly enhancing the stability of AXT under heating and UV exposure and delaying its degradation during simulated digestion. Additionally, the nanoscale structure and good biocompatibility of EVs facilitated the cellular uptake of lipophilic substances by RAW264.7 macrophages. In vivo experiments indicated that Nile Red@EVs showed good intestinal retention and were efficiently absorbed by intestinal epithelial cells. In vitro experiments demonstrated that AXT@EVs significantly reduced reactive oxygen species production, mitochondrial depolarization, and pro-inflammatory cytokines. These findings suggest that EVs not only improve the stability of AXT but also exhibit potent antioxidant and anti-inflammatory effects, providing a strategy for intervening in oxidative stress-related inflammatory responses. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s42995-026-00404-2.