Nanometric core@shell wüstite@ferrite (Fe1−xO@Fe3O4) has been extensively studied because of the emergence of exchange bias phenomena. Since their actual implementation in modern technologies is hampered by the low temperature at which bias is operating, the critical issue to be solved is to obtain exchange‐coupled antiferromagnetic@ferrimagnetic nanoparticles (NPs) with ordering temperature close to 300 K by replacing the divalent iron with other transition‐metal ions. Here, the effect of the combined substitution of Fe(II) with Co(II) and Ni(II) on the crystal structure and magnetic properties is studied. To this aim, a series of 20 nm NPs with a wüstite‐based core and a ferrite shell, with tailored composition, (Co0.3Fe0.7O@Co0.8Fe2.2O4 and Ni0.17Co0.21Fe0.62O@Ni0.4Co0.3Fe2.3O4) is synthetized through a thermal‐decomposition method. An extensive morphological and crystallographic characterization of the obtained NPs shows how a higher stability against the oxidation process in ambient condition is attained when divalent cation doping of the iron oxide lattice with Co(II) and Ni(II) ions is performed. The dual‐doping is revealed to be an efficient way for tuning the magnetic properties of the final system, obtaining Ni‐Co doped iron oxide core@shell NPs with high coercivity (and therefore, high energy product), and increased antiferromagnetic ordering transition temperature, close to room temperature.

Peptide self-assembly is ubiquitous in nature. It governs the organization of proteins, controlling their folding kinetics and preserving their structural stability and bioactivity. In this connection, model oligopeptides may give important insights into the molecular mechanisms and elementary forces driving the formation of supramolecular structures. In this contribution, we show that a single residue substitution, that is, Aib (α-aminoisobutyric acid) in place of Ala at position 4 of an -(l-Ala)-homo-oligomer, strongly alters the aggregation process. In particular, this process is initiated by the formation of small peptide clusters that promote aggregation on the nanometer scale and, through a hierarchical self-assembly, lead to mesoscopic structures of micrometric dimensions. Furthermore, we show that the use of the well-established Langmuir-Blodgett technique represents an effective strategy for coating extended areas of inorganic substrates by densely packed peptide layers, thus paving the way for application of peptide films as templates for biomineralization, biocompatible coating of surfaces, and scaffolds for tissue engineering.