Hierarchical dual confinement of thymoquinone in PLGA-PEG nanoparticles and a pectin-TEOS hydrogel enables phase-selective gastrointestinal release.

Hydrophobic natural products require delivery systems that protect the payload during gastric transit while preserving intestinal availability. Here, we engineered a hierarchical nanoparticle-in-hydrogel carrier in which thymoquinone (TQ) is first confined within PLGA-PEG nanoparticles, which are then embedded within a pectin-TEOS hydrogel, creating two sequential levels of drug confinement. PEG molecular weight and TEOS concentration were screened to tune network hydration, identifying PEG 6000 and 0.75 M TEOS as the selected formulation. Fourier-transform infrared spectroscopy, thermal analysis, X-ray diffraction and electron microscopy supported polymer integration, reduced crystalline order and incorporation of the nanoparticle compartment within the hydrogel. In SGF, cumulative TQ release at 2 h was 9.6% from directly loaded hydrogel and 5.0% from the nanoparticle-in-hydrogel formulation. Separately measured SIF profiles showed substantial intestinal-phase release. Comparative modelling of the phase-specific datasets indicates that the hierarchical carrier does not act simply as a uniformly slower depot: it suppresses premature gastric loss while permitting TQ release under intestinal conditions. TQ-loaded formulations retained concentration- and time-dependent antiproliferative activity in HeLa and HCT116 cells. Together, these findings support a dual-confinement strategy that couples gastric protection to intestinal TQ availability and provide a basis for further development of pectin-based oral delivery systems.