(617a) Magnetite Nanoparticles for Magnetic Drug Targeting

Ritter and co-workers have been exploiting nanostructured magnetic materials as a scaffold for implant assisted - magnetic drug targeting (IA-MDT). In MDT, an external magnetic field is used to attract and retain magnetic drug carrier particles (MDCPs) at a specific site in the body. However, the use of an external field alone is limited by the small magnetic forces exerted on the MDCPs, which leads to poor retention. IA-MDT represents a possible solution to this dilemma that Ritter and co-workers have been exploring. One IA-MDT approach they have been testing uses magnetic nanoparticles, such as magnetite, to enhance the capture of the MDCPs at the target site. These magnetite nanoparticles, which are far more magnetic than the MDCPs, are easily collected at the target site when placed in the magnetic field. So they are collected first, followed by the MDCPs. This approach works because the magnetic nanoparticles become magnetized in the magnetic field and thus impart a force on the MDCPs that is larger than that generated by the magnetic field alone. In effect, the magnetic nanoparticles act as a scaffold for the MDCPs to be attracted to, with both being collected and retained magnetically at the target site. This IA-MDT system was studied in vitro using a porous polyethylene cylinder to simulate capillary tissue. The magnetite nanoparticles were first captured within the porous polymer using an external magnet. They ranged in diameter from 10?100 nm. The MDCPs were then captured using the magnetite nanoparticles as a magnetic scaffold or implant, as explained above. The MDCPs were 0.87 ìm in diameter and embedded with 25 wt% magnetite. This presentation will disclose the effects of several variables on the performance of this unique IA-MDT approach in terms of the MDCP capture efficiency (CE). The fluid velocity, the distance to the magnet, the applied magnetic field, the magnetite nanoparticle size and concentration, and the MDCP concentration were studied. The results showed a significant increase in the capture of the MDCPs surrogates when the magnetite nanoparticles were present. The results also revealed considerable insight to the design of such an IA-MDT system.