Stimuli-Responsive and Biocompatible Poly(N-vinylcaprolactam-co-acrylic acid)-Coated Iron Oxide Nanoparticles by Nanoprecipitation Technique

In this present work, the preparation of hybrid poly(N-vinylcaprolactam-co-acrylic acid) (poly(NVCL-co-AA))-coated iron oxide (Fe₃O₄) nanoparticles, using the nanoprecipitation technique, is described. Iron oxide nanoparticles of about 20 nm in diameter were firstly synthesized by coprecipitation method using Pluronic F68 or Triton X-405 as stabilizers. The effect of reaction time and stabilizer content on the hydrodynamic diameters (D _h) and the mean size distribution ( Poly ) was evaluated in order to get a stable organic ferrofluid. To confirm the encapsulation of iron oxide nanoparticles by the polymer matrix, X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) were used. The effect of temperature and pH on D _h was studied by dynamic light scattering (DLS) and electrophoretic mobility (EM), respectively. The encapsulation efficiency, obtained by termogravimetric analysis (TGA), was 50.9 and 25.2%, when using iron oxide stabilized by Pluronic F68 and Triton X405, respectively. Information about the morphology of nanoparticles was achieved by atomic force microscopy (AFM) as well as conventional and cryo-transmission electron microscopy (TEM and cryo-TEM). Cryo-TEM images also showed the magnetic nanoparticles well distributed into the temperature- and pH-responsive polymer matrix.