Age-dependent efficiency of magnetic drug targeting in young and old patient-specific aortic models.

Magnetic drug targeting (MDT) offers a non-invasive and localized approach for improving therapeutic delivery in vascular diseases, but its efficiency is strongly affected by age-related hemodynamic changes. In this study, a computational framework was employed to compare MDT performance in young and old patient-specific aortic models reconstructed from clinical imaging. Blood was modeled using non-Newtonian Carreau, Power-law, and Casson-Papanastasiou rheologies, while nanoparticle motion was simulated under external magnetic fields ranging from 0.5 to 1.5 T. Across all rheological models, capture efficiency (CE) increased with particle size and magnetic field intensity. Importantly, older patients consistently exhibited slightly higher CE than younger patients, a trend driven by their reduced flow velocity, enlarged aortic lumen, and lower wall shear stress, which collectively prolonged nanoparticle residence time and reduced hydrodynamic drag opposing magnetic capture. For example, under a 1.5 T field using the Carreau model, CE reached 8.7% for 1000 nm particles in both young and old patients, but at intermediate intensities (0.5-1.25 T), older patients showed higher CE (e.g., 2.4% vs. 2.1% at 0.5 T, and 7.3% vs. 6.6% at 1.25 T). Newtonian rheology consistently over-predicted CE relative to non-Newtonian models. All applied magnetic field strengths remained within clinically acceptable safety thresholds, and field localization coincided with the target region of interest. These findings demonstrate that vascular aging enhances magnetophoretic drug capture under realistic hemodynamic conditions and underscore the need for age-aware optimization in patient-specific MDT strategies.