Hyaluronic Acid-Coated Glabridin Nanoemulsions via a Low-Energy Method: Molecular Dynamics Analysis and Enhanced Macrophage Uptake

In this study, a hyaluronic acid (HA)-coated glabridin nanoemulsion was developed for enhanced macrophage uptake using the phase inversion temperature (PIT) method. The optimized cationic nanoemulsion consisted of a 10% w/w 60:40 peppermint oil:virgin coconut oil ratio, 10% w/w Cremophor RH40, 1% w/w cetyltrimethylammonium bromide, and 1% w/w ethanol. It exhibited a small droplet size, narrow size distribution, and positive zeta potential. Molecular dynamics simulations supported the experimental results, showing that systems containing a cosurfactant formed smaller droplets than those without a cosurfactant, particularly when ethanol was used as the cosurfactant. A concentration of 0.15% w/w HA solution at a 1:10 nanoemulsion–HA ratio yielded favorable characteristics, including a small droplet size (69.98 ± 0.48 nm), narrow size distribution (0.30 ± 0.00), and negative zeta potential (−23.00 ± 2.08 mV). Transmission electron microscopy image confirmed the presence of HA coating at 0.15% w/w. The incorporation of glabridin stabilized the droplet size (67.63 ± 0.33 nm) and polydispersity index (0.36 ± 0.01) but slightly decreased the absolute zeta potential (−10.83 ± 1.91 mV), whereas the entrapment efficiency was 91.65% ± 1.52% w/w. The nanoemulsion exhibited good physicochemical stability after storage at 40 °C for 6 months. HA coating enhanced the cellular uptake of the nanoemulsion into macrophage cells. The HA-coated glabridin nanoemulsion significantly inhibited the production of reactive oxygen species and nitric oxide and it also demonstrated low cytotoxicity. These findings indicated the potential of the PIT method to produce HA-coated glabridin nanoemulsion as a receptor-mediated delivery system for treating inflammation.