A Multifunctional Magnetic Composite Material as a Drug Delivery System and a Magnetic Resonance Contrast Agent

Magnetic iron oxide coated in hydrogenation silica (Fe3O4@HSiO2) is constructed as both a tumor drug carrier and a magnetic resonance (MR) contrast agent. Colchicine (COLC) is loaded in Fe3O4@HSiO2 with the highest amount of 28.3 wt% at pH 9. The release performance of COLC can be controlled by pH, as the porous HSiO 2 shell can partially shed at pH below 3.0 to facilitate the release of COLC. MR imaging (MRI) tests prove that Fe3O4@HSiO2 at pH 3.0 (H+-Fe3O4@HSiO2) shows a stronger MR contrast enhancement than Fe3O4. Cytotoxicity experiment indicates that Fe3O4@HSiO2 has excellent biocompatibility and magnetic targeting performance. Additionally, COLC-loaded Fe3O4@HSiO2 (Fe3O4@HSiO2 -COLC) displays a higher inhibition effect on tumor cells under a magnetic field than free COLC. The visibility upon MRI, high targeting, and pH-controlled release characteristics of Fe3O4@HSiO2 -COLC are favorable to achieve the aim of reducing side effects to normal tissues, making Fe3O4@HSiO2-COLC an attractive drug delivery system for nanomedicine.