Facile preparation of boronic acid functionalized Fe-core/Au-shell magnetic nanoparticles for covalent immobilization of adenosine

The synthesis of biocompatible magnetic nanoparticles is one of the important topics in nanoscience because such materials have potential biomedical applications. Herein, we report a facile approach for surface functionalization of magnetic nanoparticles (MNPs) with boronic acid and their use for the covalent immobilization of adenosine. The iron nanoparticles were firstly coated by layer of gold using the inverse micelle method to form core–shell structure. Then, the surface functionalization of MNPs was carried out using 4-mercaptophenylboronic acid through the well-developed Au–S chemistry. The covalent immobilization of functionalized MNPs with adenosine was obtained via the strong covalent interactions of boroester linkages, which were formed between free hydroxyl groups of adenosine and boronic acid. X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM) were used to confirm the successful preparation of core–shell magnetic nanoparticles. Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), UV–visible absorption spectroscopy (UV–vis), X-ray photoelectron spectroscopy (XPS), superconducting quantum interference device magnetometer (SQUID) was employed to characterize the change of surface functionalities and to study the magnetic properties. The digital image provided a vivid observation on the separation of adenosine-immobilized MNPs under an external magnetic field.