Layer-By-Layer Modified Superparamagnetic Iron Oxide Nanoparticles with Stimuli-Responsive Drug Release Properties

Superparamagnetic iron oxide nanoparticles (SPIONs) are synthesized through ultrasound based coprecipitation method. SPIONs are coated with poly(2-isopropyl-2-oxazoline) (PIPOX) and tannic acid (TA) in a layer-by-layer (LbL) fashion at pH 4 and 25 degrees C. PIPOX/TA coated SPIONs are then loaded with doxorubicin (DOX) at pH 7.5 and 25 degrees C. DOX release from LbL-coated SPIONs is examined at pH 7.5 and pH 6 at 25 degrees C, 37 degrees C, and 42 degrees C. LbL-coated SPIONs exhibit dual responsive behavior and release the greatest amount of DOX at pH 6 and 42 degrees C. Increasing layer number decreases the colloidal stability and saturation magnetization. Superparamagnetic behavior of SPIONs retains after coating. Overall, this study shows an alternative strategy to modify the surface of SPIONs with a dual responsive polymer coating which is capable of releasing DOX at moderately acidic pH of 6 within a physiologically related temperature range. Besides, it generates fundamental knowledge for further development of SPIONs-based drug carriers.