High Drug Loading Preparation And Release Properties Of Magnetic Nanoparticles

Nanomaterials with hollow or mesoporous structure have a lot of characters, such as low density, high specific surface, good permeability and ability of holding objective molecules. As a result, magnetic hollow spheres and magnetic mesoporous spheres used as magnetic targeted drug delivery vehicles, can not only improve the loading capacity, but also are in favor of slow release of drugs due to porous structure in the surface. Based on the foregoing reasons, this paper is focused on the preparation of magnetic hollow spheres, magnetic mesoporous spheres and their application as drug delivery vehicles. The details are described as follows:(1) Magnetic hollow spheres were synthesized by a simple method based on solvethermal treatment of ferric chloride, ethylene glycol, urea and PVP. Their average diameter was about 220 nm, and the shell thickness was about 50 nm. The morphology of the product transferred from solid spheres to hollow porous nanospheres by adjusting the reaction time, and the hollow volume increased obviously with the amount of PVP increased. Magnetic mesoporous spheres with an average diameter of 180 nm were obtained based on the preparation of magnetic hollow spheres. Their pore volume was 0.3528 cm3/g, and the specific surface area was 86.39 m2/g, which was much bigger than 18.7 m2/g of magnetic hollow spheres. The morphology of the product transferred from needle-like nanoparticles to mesoporous nanospheres by controlling reaction time; with the amount of SDBS increased, the specific surface area and pore volume increased, but the average pore diameter decreased. The prepared magnetic hollow spheres and magnetic mesoporous spheres both had strong magnetic response, superparamagnetism and high crystallinity. The possible formation mechanisms of magnetic hollow spheres and magnetic mesoporous spheres were also analysed and inferred in detail.(2) The loading capacity and encapsulation efficiency of DOX incorporated onto magnetic hollow spheres and magnetic mesoporous spheres were investigated under different initial DOX concentrations. For magnetic hollow spheres and magnetic mesoporous spheres, the appropriate initial DOX concentrations were both 225μg/mL, for one aspect high loading capacity was obtained, and the other aspect the amount of drug was saved. The loading capacity and encapsulation efficiency of magnetic hollow spheres were both larger than that of magnetic mesoporous spheres, indicating that the loading capacity of magnetic hollow spheres is much better than that of magnetic mesoporous spheres. (3) For magnetic hollow spheres and magnetic mesoporous spheres, the DOX drug release both have obvious sudden release stage and slow release stage. The accumulative drug release rate of magnetic mesoporous spheres in 48 h was smaller than that of magnetic hollow spheres, indicating that magnetic mesoporous spheres show a more extraordinary sustained-release property. The release rates of both spheres at pH of 5.7 were much larger than that at pH of 7.4. As a result, using both spheres as drug delivery vehicles, the drug concentration of normal parts decreased so that the damage reduced, and the drug was released rapidly within the tumor cells so that the treatment effect of cancer was improved.