Study On PH-Responsive Controlled Release System Based On Superparamagnetic Magnrtite And Polydopamine Core-shell Nanoparticles

A pH-responsive controlled release system was constructed based on superparamagnetic Fe304-polydopamine core-shell nanoparticles which were drug-loaded through Michael addition reaction between catechol of polydopamine and thiol of chemically modified doxorubicin.Besides the pH-responsive property,the drug-loaded Fe304-dolydopamine core-shell nanoparticles also had other potential properties like magnetic-thermal,magnetic-targeting and magnetic properties.Fe304 nanoparticles were synthesized in liquid polyols at elevated temperature.DLS,TEM,XRD and FI-IR were used to characterize the structure and component.The average size of Fe304 nanoparticles was smaller than the size of single magnetic domain,with narrow size distribution and excellent water dispersibility.The superparamagnetic and high saturation magnetization properties of Fe304 nanoparticles were proved by PPMS.Two types of nanoparticles,poly dopamine and Fe304-poly dopamine core-shell nanoparticles were synthesized through the self-polymerization of dopamine under alkaline condition.PPMS indicated Fe304-polydopamine core-shell nanoparticles also had excellent superparamagnetic and magnetism-responsive properties.The size of poly dopamine nanoparticles could be controlled by adjusting the molar ratio of NH3-H2O/dopamine to match the requirements of application in vivo.The mass content ratio of Fe304 was about 5%measured by TGA.Prodrug containing thiol and acylhydrazone was synthesized based on doxorubicin.Prodrug was loaded on the nanoparticles via robust thiol-catechol reactions under oxygen and alkaline condition.TEM and DLS proved the structures and morphologies of nanoparticles almost remained the same before and after drug-loading,and the drug-loading capacity of both types were near 5%measured by UV-vis.In vitro pH triggered DOX release was performed at different pH.The results showed that the fraction of DOX released from nanoparticles was low at pH 7.4 over a 12 hour period,while faster and increased DOX release was observed at pH 5.0.In conclusion,our study provides a facile and robust strategy for the formation of pH-responsive drug delivery system,which may also have potential properties and applications in magnetic-thermal therapy,magnetic-targeting and magnetic resonance imaging.