A new synthesis and stabilization method was developed for paramagnetic nanoparticles composed of nickel and nickel oxides. Nickel/nickel oxides nanoparticles were synthesized by a method based on ligand displacement of bis(1,5-cyclooctadiene)-nickel(0), zerovalent organometallic precursor and simultaneous formation of a thiourea inclusion compound. Nickel/nickel oxides nanoparticles were stabilized with the amphipathic peptide H2N-Cys-Leu-Pro-Phe-Phe-Asp-NH2 having H2N-Leu-Pro-Phe-Phe-Asp-NH2 a peptide with potential properties for Alzheimer's disease therapy. The inclusion compound formed after displacement was characterized by X-ray powder diffraction, and nickel/nickel oxides nanoparticles were characterized using transmission electron microscopy, atomic force microscopy, UV-Visible spectroscopy, X-ray photoelectron spectroscopy, and superconducting quantum interference device magnetometry. In addition, a cell viability assay in primary rat hippocampal neurons was carried out.