Physicochemical–Electrochemical Characterization of the Nanocomposite Chitosan-Coated Magnetite Nanoparticles

Magnetite nanoparticles (MNPs) have attracted great interest due to their low human toxicity and applications in different fields. Electrochemical methods have been proposed to obtain this type of nanoparticles, allowing better control of the size and size distribution than conventional strategies. Additionally, it has been reported that when they are functionalized with chitosan, they become more stable and more effective for some applications. MNPs were electrochemically synthesized by the asymmetrical potential pulses method, then functionalized with chitosan, and subsequently characterized by physicochemical and electrochemical techniques. The MNPs synthesized by applying potential pulses showed sizes of 21.2 ± 3.6 nm by X-ray diffraction (XRD) and 28.5 ± 8.3 nm by Transmission Electron Microscopy (TEM); as well as size of 18.5 ± 6.3 nm by XRD and 32.4 ± 9.5 nm by TEM in chitosan-coated MNPs (MNPs-Chitosan). Additionally, Dynamic Light Scattering demonstrated a hydrodynamic size of 346.8 ± 35.1 nm in MNPs and 224.2 ± 21.6 nm in MNPs-Chitosan. Furthermore, their morphology and colloidal stability were evidenced by Scanning Electron Microscopy and Zeta potential. At the same time, the functionalization of magnetite with chitosan in MNPs-Chitosan was demonstrated through characteristic bands and weight losses by Fourier Transform Infrared Spectroscopy and Thermogravimetry. Finally, the redox reactions and reactivity of MNPs and MNP-Chitosan were studied by Linear Sweep Voltammetry, Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. Likewise, it was shown that the protection of chitosan offers stability to the MNPs; however, there is a facility of MNPs-Chitosan to transfer electrons, which is helpful for their application in different areas such as biomedical, environmental, and food. Graphical Abstract