In vitro digestion, cellular uptake and absorption of walnut protein-based nanoparticles mediated coenzyme Q10 nanosuspensions

Oral administration of Coenzyme Q10 (CoQ10) is hindered by its low bioaccessibility, and protein-based nanoparticles, commonly used to improve this, are vulnerable to degradation by pH, salts, and enzymes. This study examined the in vitro digestion behavior and the subsequent cellular uptake and absorption of walnut protein-based nanoparticle-stabilized CoQ10 nanosuspensions (CQ@WPNP) to investigate their potential utility in addressing these challenges. Cryo-electron microscopy (Cryo-EM), revealed structural rearrangements of CQ@WPNP during digestion, with both WPNP and CoQ10 nanoparticles remaining stable in the gastric phase, thereby preventing premature release. This stability facilitated the formation of bioaccessible tiny micelles and enlarged CoQ10 nanoparticles in the intestinal phase. Cellular uptake in Caco-2 cells revealed a 7.7-fold increase in CoQ10 uptake post-digestion, with 0.7-fold enhanced apparent permeability coefficient and favorable cellular CoQ10 levels (0.44 μg/mg protein) in Caco-2/HT29-MTX monolayers. Digested CQ@WPNP internalization occurred through an energy-dependent process involving multiple endocytic pathways, including clathrin- and caveolae-mediated endocytosis, fast endophilin-mediated endocytosis, and micropinocytosis. This study demonstrated that CQ@WPNP can serve as an oral delivery system to enhance the cellular uptake and absorption efficiency of CoQ10, highlighting the potential of walnut protein-based nanoparticles for hydrophobic nutraceutical and pharmaceutical delivery.