Features of Epirubicin Immobilisation on the Surface of the Composite Fe₃O₄/DMSA

This study evaluates the adsorption equilibrium of Epirubicin (EPI) on nanosized Fe₃O₄/DMSA composite surfaces using both two-parameter and three-parameter isotherm models. The synthesized nanoparticles possessed an average diameter of Dₐᵥ = 7.64 ± 2.22 nm, a specific surface area of 103 m²/g, a pore volume of 0.44 cm³/g, and an average pore size of 5.7 nm. Experiments conducted across EPI concentrations of 0.006–0.6 mg/ml reveal that drug immobilization is driven by a complex, energy-heterogeneous adsorption mechanism.

Among two-parameter models, the Langmuir isotherm provided the best fit for initial monolayer formation, while Sips, Toth, and Hill models confirmed surface energy heterogeneity. Additional fits from Dubinin–Radushkevich, Temkin, BET, and Redlich–Peterson (n_RP ≈ 0.85) models demonstrate a combination of physical adsorption, ion-exchange interactions, and intermolecular forces, including π-π stacking and hydrogen bonding. These structural and energetic features confirm that Fe₃O₄/DMSA nanocomposites provide efficient immobilization of EPI.