Layer-by-layer stimuli-responsive self-assembled nanocarriers for green-extracted polyphenols sequential delivery:...

Stimuli-responsive layer-by-layer (LbL) self-assembly nanocarriers have garnered considerable attention worldwide due to their simplified production process and potential technological applications, primarily as promising tools in the targeted delivery of bioactive pharmaceuticals to address the challenges of environmental stress sensitivity and poor water solubility. In this study, multi-functional LbL self-assembled nanoparticles (LbL-NPs) were designed by the sequential deposition of oppositely charged polyelectrolytes through a simplified washless assembly method to encapsulate seaweed green-extracted polyphenols (EpEPs). The effects of layer number on structural features and stability behavior under different environmental stress conditions were investigated, as well as under simulated gastrointestinal digestion conditions via the INFOGEST static in vitro sequential model. Data revealed an increase in particle size from 500 nm (monolayer NPs) to 990 nm (four-layer NPs), with uniform distribution and a clear hallmark assembly. Within the specified experimental conditions, the highest yield recorded was 23 %, with an entrapment efficiency of 94.5 % and a loading capacity of 65 %, achieved after a four-layer deposition. LbL-NPs efficiently protected EpEPs from degradation under high acid, alkali, ionic strength, and temperature. Moreover, the retention rate, bioaccessibility, and bioactivities of EpEPs improved with the number of interfacial layers in the simulated gastrointestinal tract. Compared to free EpEPs, LbL-NPs pH-responsive enhanced the retention of EpEPs in the gastric phase, reaching a bioaccessibility of 72 % in the intestinal tract. This work offers a favorable theoretical root for designing innovative stimuli-responsive delivery carriers based on LbL self-assembly and their potential applications in food and biomedical fields. Regulating the properties of the interfacial layer appears to be crucial for maintaining the physical stability and antioxidant effectiveness of assembled NPs.