| Targeted drug delivery system(TDDS) refers to the way by which drugs selectivly delivery to target organ, target tissue or target cell after topical administration of drugs via the carrier through systemic blood circulation. Magnetic drug delivery is a main way of targeted drug delivery. It is primarily by producing the nano carriers which load therapeutic drugs, then directly arrived to the lesion under magnetic guidance, while decreasing potential damage to healthy tissues. Magnetic nano drug carriers can controlled release drugs, prolong the time of medicine affection, enhance drug effects, reduce the toxicity and improve the stability of the drugs. Thus, magnetic drug materials have a broad application prospect in the treatment of cancer as well as cardiovascular disease.Magnetic drug loading materials is usually the core-shell structure composed of three parts:one is the guiding magnetic core, second is the shell which has affinity and biocompatibility. Last is the drugs combined with internal particles or shell material. In this paper, we use superparamagnetic nano-Fe3O4as magnetic core, good biocompatibility of HAP/CS as shell scaffold and use dexamethasone in vitro drug release simulation. The main content of our study include three parts:1、Using FeCl2, FeCl3as raw materials, urea and hydrazine hydrate as PH regulator, nano-Fe3O4particles were fabricated under the condition of nitrogen protection and strring. Nano-Fe3O4particles were surface modified because Fe3O4nanoparticles are easy to agglomerate leading to poor dispersed suspension property of particles. Nano-Fe3O4particles modified with monolayer of stearic acid and bilayer of sorbitol were prepared. The as-prepared samples were characterized by X-ray diffraction, Fourier transform infrared spectroscope, transmission electron microscope, energy dispersive spectrometer, thermal gravity, magnetic analysis. The result indicates that main crystal phase is nano-Fe3O4of the prepared three samples without impurity phase, stearic acid and sorbitol are successful in the surface modification of nano-Fe3O4, particle sizes of about20nm, showing superparamagnetic. The content of surface polymer in nano-Fe3O4is high after double layers modification, ensuring no deposition at least15days. It lay the foundation for the subsequent experiments.2、Using Ca(OH)2, H3PO4as raw materials, the PH value of reaction solution was controlled at10, while adding double modified Fe3O4nanoparticles as nucleating agent. Using the method of acid-base neutralization to produce nano-hydroxyapatite, then encapsulated on the surface of nano-Fe3O4to form nano-Fe3O4/nano-hydroxyapatite bis-phase composite carrier. Chitosan will have an cross-link effect in the acidic environment by adding chitosan in acid solution. Three-phase composite carrier of nano-Fe3O4/nano-hydroxyapatite/CS were prepared after chitosan encapsulate in composite microspheres. The as-prepared composite carrier were characterized by XRD、FTIR、TEM、 MTT、VSM. The results show that as-prepared carrier showed superparamagnetic, size of about100nm.HAP particles in bis-phase composite carrier were spherical, and short-rod like in three-phase composite carrier. Cell toxicity reaction in bis-phase composite carrier and three-phase composite carrier are1grade or0grade which has a role in promoting cell proliferation.3、Magnetic nano carriers were simulated in vitro drug release using dexamethasone, The simulation results demonstrate that drug loading and encapsulation efficiency of dexamethasone in bis-phase composite carrier as well as three-phase composite carrier were79mg/g,6%, and95mg/g,14%respectively. So adding chitosan is conducive to improve drug loading in nano carriers, most importantly, enhance release properties and encapsulation efficiency of drugs. |
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