Superparamagnetic iron oxide nanoparticles for delivery of tissue plasminogen activator

Magnetic nanoparticle (MNP) modified by carboxymethyl dextran (CMD) was synthesized and characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, superconducting quantum interference device, dynamic light-scattering, thermogravimetric analysis, and X-ray diffraction. CMD coating on the particle surface provides abundant-COOH functional groups for conjugating with a thrombolytic drug, recombinant tissue plasminogen activator (rtPA). CMDcoated MNP (CMD-MNP) prepared with higher CMD/MNP ratios had higher CMD content, less iron content, more-COOH surface groups, smaller hydrodynamic diameter, and smaller saturation magnetization. The in vitro biocompatibility study using lactate dehydrogenase assays indicated that CMD-MNP elicited no cell cytotoxicity. The optimum drug loading could be achieved by contacting 0.25 mg rtPA with 5 mg CMD-MNP where all rtPA is immobilized to the magnetic nanocarrier with full retention of its thrombolytic activity.