Ferromagnetic seeding for the magnetic targeting of drugs and radiation in capillary beds

A new implant assisted-magnetic drug targeting approach is introduced and theoretically analyzed to demonstrate its feasibility. This approach uses ferromagnetic particles as seeds for collecting magnetic drug carrier particles at the desired site in the body, such as in a capillary bed near a tumor. Based on the capture cross section (λc) approach, a parametric study was carried out using a 2-D mathematical model to reveal the effects of the magnetic field strength (μ0H0=0.01–1.0 T), magnetic drug carrier particle radius (Rp=20–500 nm), magnetic drug carrier particle ferromagnetic material content (xfm,p=20–80 wt%), average blood velocity (uB=0.05–1.0 cm/s), seed radius (Rs=100–2000 nm), number of seeds (Ns=1–8), seed separation (h=0–8Rs), and magnetic drug carrier particle and seed ferromagnetic material saturation magnetizations (iron, SS 409, magnetite, and SS 304) on the performance of the system. Increasing the magnetic field strength, magnetic drug carrier particle size, seed size, magnetic drug carrier particle ferromagnetic material content, or magnetic drug carrier particle or seed saturation magnetization, all positively and significantly affected λc, while increasing the average blood velocity adversely affected it. Increasing the number of seeds or decreasing the seed separation, with both causing less significant increases in λc, verified that cooperative magnetic effects exist between the seeds that enhance the performance. Overall, these theoretical results were encouraging as they showed the viability of this minimally invasive, implant assisted-magnetic drug targeting approach for targeting drugs or radiation in capillary beds.