Development of citrate-stabilized Fe3O4 nanoparticles: Conjugation and release of doxorubicin for therapeutic applications

We demonstrate a single-step facile approach for the fabrication of citric acid functionalized (citrate-stabilized) Fe3O4 aqueous colloidal magnetic nanoparticles (CA-MNP) of size 8-10 nm using soft chemical route. The surface functionalization of Fe3O4 nanoparticles with citric acid was evident from infrared spectroscopy, thermal and elemental analyses, and zeta-potential measurements. The drug-loading efficiency of CA-MNP was investigated using doxorubicin hydrochloride (DOX) as a model drug to evaluate their potential as a carrier system. The quenching of fluorescence intensity and decrease in surface charge of drug loaded CA-MNP strongly suggest the interaction/attachment of drug molecules with CA-MNP. More specifically, the present investigation discusses a method for entrapping positively charged drugs on to the surface of negatively charged CA-MNP through electrostatic interactionsandsuggeststhatbounddrugmoleculeswillbereleasedinappreciableamountsinthe mild acidic environments of the tumors. Furthermore, the aqueous colloidal stability, optimal magnetization, good specific absorption rate (under external AC magnetic field) and cytocompatibility with cells suggested that CA-MNP is appropriate candidate for biomedical applications. (C) 2010 Elsevier B.V. All rights reserved.