Preparation and characterization of pH-responsive hydrogel magnetite nanocomposite

Hydrogel magnetite nanocomposite (HMNC) was fabricated by in situ development of magnetite nanoparticles in polyacrylamide (PAM) hydrogel. The formation of magnetite nanoparticles and their magnetic properties were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and super conducting quantum interference device. The average particle size was 3–5 nm as demonstrated by transmission electron microscopy. The thermal property of HMNC was determined by thermo-gravimetric analysis. It was found that HMNC had a lower thermal stability at the initial decomposition temperature and higher thermal stability at the final decomposition temperature. It was also found that HMNC showed pH sensitive behavior which is not present in plain hydrogel, and the HMNC prepared with a 100% iron salt solution showed a high protein adsorption characteristic at pH 7.0.