Site-directed drug release performance in chemically-modified FeFe2O4 and CoFe2O4 magnetic nanoparticles for controlled drug delivery systems

This paper proposes a novel approach to the development of magnetic nanoparticles (MNPs) for drug delivery systems. The nanocarriers are made from FeFe₂O₄ and CoFe₂O₄ MNPs that were synthesized by combustion, coated with silica derivatives, and then conjugated to ciprofloxacin. The drug release tests were performed into simulated body fluid consisted of ciprofloxacin adsorbed onto MNPs composites with various mass ratios of hydroxyapatite:FeFe₂O₄ (M) and hydroxyapatite:CoFe₂O₄ (C), evaluated by pharmacokinetic models, and regression analysis. The MNPs were characterized by morphological and structural characterizations. Drug release was measured with a discontinuous method (paddle apparatus) and with a continuous method simulating a blood vessel. XRD and FTIR showed that all of the MNPs were successfully synthesized, coated, and drug conjugated. VSM exhibited superparamagnetic characteristics, with saturation magnetization varying between 9.74 and 32.90 emu/g and 9.65–30.00 emu/g for FeFe₂O₄ and CoFe₂O₄, respectively, as a function of the MNPs mass ratio on the nanocarrier. The discontinuous method showed drug release over 80% (FeFe₂O₄), while the CoFe₂O₄-based achieved over 40%, which indicates that the incorporation of hydroxyapatite favors the carrying of ciprofloxacin. The continuous method showed a drug release under 14% and 14.5% for the FeFe₂O₄ and CoFe₂O₄ based nanocarriers respectively, and this reduction of the desorbed drug compared to the discontinuous method may have occurred due to the action of the applied magnetic field. The mathematical model provided the release speed and time to reach the maximum fraction desorbed (<4 min), highlighted for M₂ (13.8%) and C₃ (14.5%) drug released, with a mass ratio of 50:50 and 30:70, respectively. The proposed continuous release model showed that the action of site-directed targeting significantly affected the amount of drug released. This identifies the optimal device for the development of magnetic nanoparticulate systems for drug delivery and tissue engineering.