A synthesis of polyethylene glycol (PEG)-coated magnetite Fe3O4 nanoparticles and their characteristics for enhancement of biosensor

Abstract

The magnetite Fe _3 O _4 nanoparticles were synthesized by using chemical co-precipitation method and these nanoparticles were successfully coated by polyethylene glycol (PEG) with variation concentrations of PEG. The magnetite Fe _3 O _4 nanoparticles used as a bimolecular label (nano-tags), exhibiting a soft magnetic behavior with magnetization ( M _s ) of 77.16 emu g ^−1 and coercivity ( H _c ) of 50 Oe respectively. The polyethylene glycol (PEG) was used as a biocompatible polymer. The x-ray diffraction (XRD) patterns of the Fe _3 O _4 showed that Fe _3 O _4 was well crystallized. It also confirmed the existence of invers spinel. The diffraction peak of 35.4° was used to calculate the crystallite size. The estimation of Fe _3 O _4 average crystallite size is 12 nm, while the PEG-coated Fe _3 O _4 nanoparticles is 8.6 nm. The transmission electron microscopy (TEM) images of Fe _3 O _4 showed that the morphology of magnetite Fe _3 O _4 nanoparticle is spherical in shape with uniform grain size and good dispersibility despite the agglomeration it found in some place. The addition of PEG can decrease the agglomeration and reduce the particle size. The existence of PEG layer on Fe _3 O _4 was confirmed by Fourier transform infrared (FTIR) spectroscopy. The result of Vibrating Sample Magnetometer (VSM) showed that saturation magnetization ( M _s ) of Fe _3 O _4 nanoparticles decreased from 77.16 to 37.15 emu g ^−1 with the increase of PEG weight from 0% to 50%. Such Fe _3 O _4 nanoparticles with favorable size and tunable magnetic properties are promising biosensor applications.

Keywords

• polyethylene glycol (PEG)
• co-precipitation method
• biosensor applications
• magnetite Fe3O4
• nanoparticles