pH-Responsive Release Hydrophilic Colloids: Preparation and Characterization of Lutein/Retinol Coloaded Nanoparticles and Their Hydrogel Beads

Lutein (Lut) and retinol (Ret) exhibit synergistic antioxidant effects yet suffer from poor water solubility and stability. The DPPH assay confirmed that their 1:1 ratio (350 μg/mL each) yielded a high free radical scavenging rate of 86.52 ± 2.24%. Via microfluidic technology, 130 nm Lut/Ret coloaded nanoparticles (L/R-NPs) were successfully prepared with Zein and PVP K30 as carriers; molecular dynamics indicated that van der Waals and electrostatic interactions stabilize their core–shell structure. Embedded in sodium alginate–agarose (SA-Agar) hydrogel beads (L/R NP -GBs) with high encapsulation efficiency (EE), 1:1 L/R NP -GBs had lower rigidity, better elasticity, and reduced dysphagia risk compared to the 1:3 ratio. Crucially, L/R NP -GBs showed pH-responsive release: minimal at pH 1.2, sustained at pH 6.8, enabling intestinal targeting and enhancing bioaccessibility. This “nanoparticle-hydrogel bead” system effectively addresses Lut/Ret delivery challenges, offering a promising strategy for fat-soluble bioactives.