SILICA-COATED MAGNETITE NANOPARTICLES PREPARED BY CO-PRECIPITATION METHOD FOR PROTEIN DETECTION

Abstract

Fe3O4 magnetite nanoparticles (MNPs) were prepared using the co-precipitation method at room temperature. The MNPs were modified by coating with SiO2 and APTES to enhance their efficiency for protein detection applications. The MNPs were characterized by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy (SEM/EDXS), Fourier Transform Infrared (FT-IR), Thermogravimetry Analysis (TGA), X-ray diffraction (XRD), and Vibrating Sample Magnetometer (VSM). The results indicated differences in the size of particles, as around 10-40 nm and there was observed agglomeration among the sample, which, according to SEM image.  Moreover, FT-IR analysis confirmed the presence of silica and NH2 coating on the magnetic nanoparticle surface. The immobilization of amine molecules (-NH2) onto the SiO2 surface is evident in TGA. The crystalline structure of the MNPs was identified as the cubic inverse spinel structure of pure-phase polycrystalline magnetite through XRD. Results from the vibrating sample magnetometer (VSM) revealed that the prepared MNPs exhibited a high magnetization saturation (Ms) of 61.31 emu/g and a coercive field strength (Hc) of 30.94 Oe (near ferromagnetism). After being surface modification with SiO2, Ms reduced to 43.24 emu/g, which further decreased to 40.17 emu/g following modification with APTES. Additionally, the Bradford assay was used to measure the percentage binding for BSA, assessing the efficiency of protein detection application.