The Capture Efficiency Modeling And Influencing Factors Analysis Of Magnetic Drug Targeting Delivery

Retinal vascular occlusive disease is a common medical problem which can cause serious damage in visual function. Conventional treatments such as massage, puncture, medicaments and so on can not receive obvious effect and also take a long time. The method of magnetic drug targeting delivery is to load drug onto the magnetic nanoparticles and make it move and focus on the target site with the help of external magnetic field. It can improve the drug concentration of the drug target site, and reduce adverse effect of drugs on normal tissues. To use magnetic drug targeting methods as the treatment of retinal vascular occlusive disease can improve the efficacy of the drug and has a wide range of purposes and potentially huge market demand. Although there are many researches on magnetic drug targeting system, research about embolic vessel is lack and further work is still needed in the capture of magnetic drug. To this end, with Shanghai Jiaotong University Medical Technology Fund, the paper dose research on the capture efficiency model and influencing factors of magnetic drug targeting from two aspects of theory and experiment.In this paper, completed work and the results are as follows:1. This paper presents a mathematical model to describe the capture efficiency in the vascular flow field with the applied external magnetic field. Magnetic nano-carrier particles move in the blood vessels under magnetic force and fluid force. After different blood models are compared, non-Newtonian fluid multiphase flow model is selected according to retinal fundus vascular blood and the magnetic field characteristics, Carson - Newton model consisting of rectangular magnet system is established and the magnetic particle trajectories are obtained. Based on which, capture efficiency of the magnetic particle in three-dimensional space is derived, optimization model of drug capture volume is proposed and the influence of various parameters in magnetic drug targeting system on the capture efficiency is further discussed.2. After the initial value of the model is set, using the Runge-Kutta algorithm and the dichotomy, flow field and magnetic field in the blood vessel are analyzed by means of MATLAB numerical simulation. Blood flow speed, magnetic particle trajectory and capture efficiency are also compared when different models are used. Capture efficiency in 2D plane and 3D space are also brought into comparison. Simulation results show that the use of non-Newtonian Casson fluid can better describe the blood and magnetic field generated by rectangular permanent magnet is more effective; other conditions being equal, larger particle radius and radius ratio of the magnetic material, greater magnetic field strength, smaller distance between magnet and blood vessel and smaller blood vessel radius produce higher capture efficiency. In actual experiment, drug efficacy can be improved by modifying these parameters; when the magnetic material radius ratio reaches 0.75, the volume of captured drug is the biggest. In the magnetic drug preparation process, we can refer to this value to achieve system optimization.3. Based on the causes and clinical manifestations retinal vessel occlusion, for different situation, this paper proposes rigidity and flexibility embolization model, simulates the model with CFD tools like Gambit and Fluent, theoretically analyzes the influence of vessel occlusion on blood flow velocity and pressure, as well as the effects of embolism size, blood vessel elasticity, magnetic fields scope on magnetic particle capture efficiency in magnetic drug targeting system, which provides theoretical basis for the clinical treatment.4. Finally, this paper further verifies the mathematical model of the magnetic particle capture efficiency by in-vitro experiment. Nano-magnetic particles solution with fluorescent labeling are uniformly pushed into the pipe by push pump. When the solution flows through the magnetic field generated by the rectangular magnet, part of the magnetic particles are captured. The volume of captured magnetic particles can be obtained by measuring the fluorescence intensity of the solution, thus magnetic particle capture efficiency can be derived. The experiment analyzes the influence of the solution's flow rate and magnetic field strength over the magnetic particle capture efficiency, and verifies the validity and accuracy of the mathematical model. This paper summarizes the problems encountered in the experiment and experimental phenomena, such as magnetic particle capture balance and so on, which provide a reference for follow-up experiments and even experiment on human being.In summary, Nano-magnetic particles capture efficiency model and embolization in retinal vessel model introduced in this paper provide valuable reference data for the use of magnetic drug targeting methods in the treatment of retinal vascular occlusive disease after experimental verification.