Analysis of magnetic drug carrier particle capture by a magnetizable intravascular stent: 1. Parametric study with single wire correlation

The feasibility of using a magnetizable intravascular stent (MIS) as part of a magnetic drug targeting (MDT) system, which consists of magnetic drug carrier particles (MDCPs), an external magnetic field source, and the MIS, is introduced and theoretically analyzed. This new approach exploits the use of high gradient magnetic separation (HGMS) principles through the MIS, which has been placed in a blood vessel adjacent to the target site, to vastly improve the targeting of the MDCPs at this site. The performance of the MDT system was based on the ability of one of the wires in the MIS to capture the MDCPs, with the capture cross-section evaluated from a single wire HGMS correlation in the literature. A parametric study showed that the dimensionless capture cross section (with respect to the wire radius) increases with lower blood velocities (0.02-0.9 m/s), higher applied magnetic field strengths (0.2-2.0 T), larger MDCPs (0.2-10 mum radius) containing more (10-100%) and stronger ferromagnetic material (iron > magnetite), and smaller wires (20-150 mum in radius) comprised of stronger ferromagnetic material (iron > 430 SS > nickel > 304 SS). Reasonable capture cross-sections, ranging between 2 and 3, but as high as 12, times the radius of the wire, were easily attained with just a single wire and under extreme flow conditions of 0.9 m/s that are typical of large arteries. Overall, these results show considerable promise for an HGMS-assisted MDT system with many potential applications for MIS devices. (C) 2004 Elsevier B.V. All rights reserved.