Resumen
In this study, covalent conjugation of thrombolytic drug urokinase to water-soluble magnetic nanoparticles (NPs) is proposed to enhance the efficiency of thrombolysis. Hydrophobic NPs of oleic acid (OA)-coated Fe3O4 are first synthesized and then surface-modified with the amphipathic copolymer poly(maleic anhydride-alt-1-octadecylene) (PMAO) to form water-soluble NPs of PMAO-OA-Fe3O4 with monodispersed sizes. PMAO-OA-Fe3O4 NPs display a good water-based stability without aggregation at near neutral pH and show good magnetic separation characteristics. The thrombolytic drug urokinase is then covalently linked with the former product through dehydration condensation reaction between the amino and carboxyl produced by dehydration of the anhydride under N-Ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Transmission electron microscope (TEM) images and dynamic light scattering (DLS) results show that the urokinase@PMAO-OA-Fe3O4 NPs are uniformly dispersed in water. The in vitro thrombolytic effect based on the manipulation of magnetic coupling, combined with static and alternating current (AC) magnetic fields, in a mimic blood-vascular system was studied. Drug release test shows that AC magnetic field can be used as switch and accelerator for NPs to release drugs. In addition, thrombolytic efficiency is nearly four times that of pure urokinase. This indicates that the coupling magnetic field may be a promising method to improve thrombolytic effect of the prepared magnetic carrier drug conjugates.