The stable superparamagnetic colloidal suspension of chitosan-poly(acrylic acid) (CS-PAA)/Fe3O4 nanoparticles was synthesized by graft copolymerization AA on the surface of CS stabilized Fe3O4 nanoparticles. The size, size distribution, structure, and magnetic properties of the resultant CS-PAA/Fe3O4 nanoparticles were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), dynamic light scattering, Fourier transform infrared spectroscopy, x-ray diffraction, and vibrating sample magnetometry (VSM). FE-SEM and TEM showed the spherelike morphology of CS-PAA/Fe3O4 nanoparticles with their diameter ranging from 15 to 60 nm. VSM measurements indicated that CS-PAA/Fe3O4 nanoparticles preserved the superparamagnetism. CS-PAA complex was proved to be a good stabilizer to prepare the well-dispersed suspension of superparamagnetic Fe3O4 nanoparticles. The stabilizing mechanisms were attributed to the electrostatic repulsion and steric hindrance. The controlled release of entrapped camptothecin from these magnetic nanoparticles was studied and the release mechanism was analyzed.
Non-alcoholic steatohepatitis is a burgeoning health problem. To diagnose NASH with magnetic resonance imaging (MRI), an effective contrast agent, a stable suspension of superparamagnetic Fe(3)O(4) nanoparticles, were newly developed. The negatively charged Fe(3)O(4) nanoparticles were coated with positive chitosan (CS) firstly, and then assembled with poly(vinyl acetate-methylacrylic acid) (P(VAc-MAA)). Transmission electron microscope and dynamic light scattering confirmed that the obtained P(VAc-MAA)/CS/Fe(3)O(4) nanoparticles had a spherical or ellipsoidal morphology with an average diameter in the range of 14-20 nm. The superparamagnetic property and spinel structure of the Fe(3)O(4) nanoparticles were well preserved due to the protection of the P(VAc-MAA)/CS layers on the surface of the Fe(3)O(4) nanoparticles. The in vivo rat experiments confirmed that the P(VAc-MAA)/CS/Fe(3)O(4) nanoparticles were an effective contrast agent for MRI to diagnose NASH.
A novel simple method was developed to successfully synthesize biocompatible N-carboxyethylchitosan (NCECS) with a substitution degree of approx. 41% using the Michael addition reaction. The NCECS structure was characterized by Fourier transform infra-red spectrometry (FT-IR), (1)H-NMR, elemental analysis, X-ray diffraction spectrometry (XRD) and thermogravimetric analysis (TGA). The physicochemical properties of NCECS in solution are found to be strongly dependent on the pH value. In the pH range of 5.0-5.5, NCECS aggregates in dilute aqueous solution as evident by steady-state fluorescence spectroscopy and viscosimetry. The aggregated NCECS shows a spheric morphology from the atomic force microscopy (AFM) study. The possible aggregation mechanism was discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.