An Alternating Magnetic Field-Controlled Drug Delivery System Based on 4,4'-Azobis (4-cyanovaleric Acid)-Functioned FeO@Chitosan Nanoparticles.

Herein, we designed chitosan-coated FeO nanocomposites for the control release of drugs by an alternating magnetic field (AMF). The chitosan-coated FeO nanoparticles (FeO@CS) were prepared by a alkaline co-precipitation method, and then, the model drug toluidine blue (TB) was covalently grafted onto the surface of the nanocomposite by a two-step amide reaction with the thermosensitive molecule 4,4'-azobis (4-cyanovaleric acid) (ACVA) as the linker group. The prepared nanocomposites were superparamagnetic and showed high magnetization saturation (about 54.0 emu g). In vitro hydrothermal release studies showed that most parts of the TB would be effectively enclosed within the nanocarriers at lower ambient temperatures (23 or 37 °C) due to the molecular bonding of ACVA. The results of kinetic fitting of hydrothermal release data showed that TB released from nanoparticles followed first-order kinetics (R > 0.99) and the Korsemeyer-Peppas model (R > 0.99, n < 0.5). Most importantly, a single magnetron release experiment demonstrated an approximately linear relationship between the cumulative release of the drug and the duration of action of AMF (R = 0.9712). Moreover, the increase in the cumulative release of the drug can be controlled by controlling the switch of the AMF generation device. Therefore, the ACVA-modified FeO@CS nanocarrier designed in this study is a promising model for drug delivery that enables the control of drug release dose by AMF.