The Dynamics Of Magnetic Targeted Drug Delivery Research

In conventional drug delivery the drug is administered by intravenous injection; it then travels to the heart from where it is pumped to all regions of the body. For a small target region that the drug is aimed at, this method is extremely inefficient and leads to much larger doses (often of toxic drugs) being used than necessary. In order to overcome this problem a number of targeted drug delivery methods have been developed. Among them, the magnetic targeted drug delivery system is one of the most attractive strategies due to its non-invasiveness, high targeting efficiency and minimizing the toxic side effects on healthy cells and tissues. Magnetic drug targeting therapy can be used for the medical treatment of various diseases, especially cancer, and cardiovascular and endovascular diseases, such as stenosis, thrombosis, aneurysm and atherosclerosis, etc.. Although there have been a number of promising in-vitro and in-vivo trials for magnetic drug targeting, very few researchers have addressed the hydrodynamics of magnetic drug targeting. Therefore, the transport issues related to magnetic drug targeting are still poorly understood, which does retard its application widely. It's very important to study the flow of the ferrofluids in the blood vessel under the action of an external magnetic field.A mathematical model is presented to describe the hydrodynamics of ferrofluids as drug carriers flowing in a blood vessel under the applied magnetic field. According to the mass and momentum conservation laws and the constitutive relations between the characteristic of ferrofluids and the flow stress, it can be still considered by means of microfluid flow with continuum theory in which the viscous force is dominant over the gravity force, in additional to the magnetic force as a new body force. In this model, the magnetic force and the asymmetrical force are added and an angular momentum equation of magnetic nanoparticles under the applied magnetic field is modeled.And engineering approximations are achieved by retaining the physically most significant items in the mathematical model due to the mathematical complexity of the motion equations. So the angular equation is decoupled from the linear equation and the continuity equation, momentum equation and state equation are obtained.Numerical simulations are performed to obtain better insight into the theoretical model with computational fluid dynamics. A 2D of thrombosis vessel and a 3D of aneurysm are simulated under different intensities. The simulations are in favor of insight into the theoretical analysis and the clinical application of magnetic targeting drug delivery.Moreover, the hydrodymanics of ferrofluids flow in a tumor vessel is analyzed. Relative to most normal tissues, tumor blood flow is highly heterogeneous because of extravasation due to high permeability. The hydrodynamic model in a tumor vessel is derived and the approximation solution is obtained. The pressure, velocity and flux profiles of ferrofluids are analyzed to determine these variables related to the magnetic intensity in a tumor vessel.Finally, animal experiments and MR imaging validate the hydrodynamic model. The target site of right kidney in SD rats is detected by MRI. The results of the experiment show that the image of the target site under the magnetic field is darker than that no magnetic field. And in the target site the color becomes dark and the sigals decrease along with the magnetic intensity.In summary, after imposing a magnetic field the velocity decreases and the pressure drop increases at the target position as the magnetic field intensity increases. It makes more stagnancy of ferrofluids to get the required concentration of drug delivery. Simulation results are provided in accord with animal experiments. Thus, this model better simulates the flow state in the blood vessel for magnetic targeting drug delivery. Results provide the important information and can suggest strategies for improving delivery in favor of the clinic application.