Passive diffusion in Stratum corneum membrane of hybrid nanoemulsions based on Carapa guianensis oil and FE₃O₄ nanoparticles

This study evaluated the passive diffusivity of hybrid nanoemulsions (CGNE) composed of Carapa guianensis oil polymers and Fe₃O₄ nanoparticles through the stratum corneum membrane. Fe₃O₄ was synthesized by the coprecipitation method, the polymers by polycondensation, and CGNE by ultrasonic homogenization. Passive diffusivity was assessed in vitro using a Franz-type diffusion cell. Nanoemulsions with different concentrations were characterized by XRF, UV-Vis, TEM, and EPR. XRF confirmed Fe and Cu signals, with CGNE showing the highest Fe concentration. UV-Vis spectra exhibited absorption peaks at 230–260 nm, shifting with polymer proportion and correlating with Fe₃O₄ content. TEM revealed nanoparticle clusters with crystalline spacing consistent with Fe₃O₄, while EPR confirmed superparamagnetic behavior. In permeation assays, the CGNE formulation achieved the best performance, with 1.61 mg permeated in 10 h e molecular flux up to 205 µg·cm⁻²·h. Lower nanoparticle concentrations (CGNE 1–3) showed reduced flux, confirming the direct correlation between Fe₃O₄ content and diffusivity. The one-compartment model fitted the kinetics with high accuracy. These findings demonstrate that magneto-bioactive nanoemulsions combining Amazonian oil and Fe₃O₄ nanoparticles are promising vehicles for sustainable transdermal drug delivery.