Fabrication and characterization of novel magnetic/luminescent multifunctional nanocomposites for controlled drug release

Abstract

In this study, a new kind of multifunctional drug-release system combined with the interesting properties of up-conversion fluorescence, magnetism and controlled drug release was successfully prepared by encapsulation of NaYF₄:Yb,Er nanocrystals, Fe₃O₄ functionalized α-ZrP nanocomposites and gentamicin sulfate (GS) with chitosan (CHI). In this system, the NaYF₄:Yb,Er nanocrystals were adsorbed on the surface of zirconium bis-(monohydrogen orthophosphate) monohydrate (α-ZrP), while GS and Fe₃O₄ nanoparticles were intercalated into the interlayer of α-ZrP. Additionally, a thin layer of chitosan enwrapped the above nanocomposites. The resultant nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, photoluminescence spectra (PL), magnetometry and other characterization methods. The results revealed that the as-prepared multifunctional nanocomposites exhibited efficient upconversion luminescence and magnetism that had potential in magnetic separation and bioimaging. Meanwhile, in vitro drug release tests using the obtained nanocomposites (pH 7.4 buffer solution at 37 °C) indicated that the nanocomposites exhibited a prolonged drug release rate. Further, the antibacterial activity of GS released from the system on Gram-negative Escherichia coli was tested. Our results suggested that the obtained multifunctionalized nanomaterials could take full advantage of each component, and might be very attractive for a variety of biomedical applications, such as bioimaging, drug targeting and bioseparation.