Home Need for a Change Ferrofluids Dynamics of MDT Future References

 

 

 

 

 

 

Text Box: [6. FeRx San Diego] Text Box: Dynamics of Magnetic Drug Targeting While the basic principle behind MDT is quite simple, the hydrodynamics of the method are still not fully understood. Both shear from pulsatile flow and the external magnetic force collectively govern the movement of ferrofluids placed in the blood stream. While the nanoparticles may arrive at the target site, problems arise if the magnetic force is outweighed by the shear force placed upon the particles. For example, if the imposed magnetic field does not provide a force strong enough to secure the particles at the target location, the drug will be swept away with the pulsatile flow. For this reason, a high importance must be placed on the ability for functionalized magnetic particles to remain at the target site long enough to allow the desorption of the drug. A study by Ganguly et al. looked at the accumulation of nanoparticles in 1Hz pulsatile flow with a Reynolds number of 382. The study found that the particles downstream from the magnet are aligned in the form of a streakline at the bottom of the vessel. This was seen to occur because of the higher density of ferrofluid compared to the distilled water in which the particles were mixed. As the flow approached the targeted area, the local magnetic field progressively increased, the diffusive spread of the ferrofluid decreased and aggregation increased. Experimental data showed a clear concentration of ferrofluid in the form of a hemispherical region. Obtaining multiple images over time, an apparent aggregation phase showed a growing size of the hemispherical region. Locations at the center of this region had the highest magnetic fields while areas on the edges of the region experienced lower magnetic fields. After the region expanded to a certain distance away from the focal point, the shear force from oncoming flow matched that of the magnetic field. Therefore a "washaway region" was seen to appear at the trailing edge of the mass. This quantitative experiment is able to give treatment developers an idea of how much ferrofluid can accumulate before being swept away by oncoming flow. Additionally, if a known amount of particulate matter will accumulate, the necessary concentration can be estimated for a give volume of ferrofluid [1],[2].  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Text Box: Clinical Trials One of the first clinical trials by Lubbe et al. used magnetic drug targeting to treat solid tumors. This study used ferrofluid with 100nm particles to which the drug epirubicine was chemically bound. The method of binding allowed for reversible ionic bond between drug and particles. This approach allowed for the drug to release from the particle at a given point in time. The test included 14 patients suffering from advanced solid tumors of which alternative cancer treatment failed. The patients were broken into two groups: the control group which received the epirubicine compound and traditional chemotherapy without the application of a magnet, and the test group which received varying levels of the epirubicine compound directed by a 0.5T or 0.8T magnet. The compound was infused over 15 minutes in a vein contralaterally to the tumor for both groups. Additionally, individuals in the test group had the permanent magnet placed near the tumor outside of the body for at least 60 minutes. The results of the study suggested that the treatment was biologically well tolerated and that ferrofluid was able to be directed to the tumors in half the subjects in the test group [2].

 

 

 

 

 

 

 

 

BME 240

Jaime Schmieg