Mind the Particle Rigidity: Blooms the Bioavailability via Rapidly Crossing the Mucus Layer and Alters the Intracellular Fate of Curcumin

Overcoming intestinal epithelial barriers to enhance bioavailability is a major challenge for oral delivery systems. Desirable nanocarriers should simultaneously exhibit rapid mucus penetration and efficient epithelial uptake; however, they two generally require contradictory structural properties. Herein, we proposed a strategy to construct multiperformance nanoparticles by modifying the rigidity of amphiphilic nanostructures originating from soy polypeptides (SPNPs), where its ability to overcome multibarriers was examined from both in vitro and in vivo, using curcumin (CUR) as a model cargo. Low-rigidity SPNPs showed higher affinity to mucin and were prone to getting stuck in the mucus layer. When they reached epithelial cells, they tended to be endocytosed through the clathrin and macropinocytosis pathways and further transferred to lysosomes, showing severe degradation and lower transport of CUR. Increased particle rigidity generally improved the absorption of CUR, with medium-rigidity SPNPs bloomed maximum plasma concentration of CUR by 80.62-fold and showed the highest oral bioavailability. Results from monocultured and cocultured cell models demonstrated that medium-rigidity SPNPs were least influenced by the mucus layer and changes in rigidity significantly influenced the endocytosis and intracellular fate of SPNPs. Those with higher rigidity preferred to be endocytosed via a caveolae-mediated pathway and trafficked to the ER and Golgi, facilitating their whole transcytosis, and avoiding intracellular metabolism. Moreover, rigidity modulation efficiently induces the reversible opening of intercellular tight junctions, which synergistically improves the transport of CUR into blood circulation. This study suggested that rigidity regulation on food originated amphiphilic peptides could overcome multiple physiological barriers, showing great potential as natural building block toward oral delivery.