Lysine as size-control additive in a bioinspired synthesis of pure superparamagnetic magnetite nanoparticles

Magnetite nanoparticles (MNPs) are being used in a number of nanotechnological applications, especially biomedical, both in diagnosis and in therapeutics such as hyperthermia agents and as drug nanocarriers for targeted chemotherapy. However, the development of efficient methodologies to produce novel MNPs with the specific requirements needed for biomedical applications is still challenging. In this context, biomimetic approaches taking use of magnetosome proteins expressed as recombinant and/or polyamino acids are becoming of great interest. In fact, these protocols give rise to magnetite nanoparticles of adequate size, magnetic properties and surface functionalization that make them compatible for biomedical applications. In this respect, herein we show for the first time that lysine (Lys), unlike other amino acids like arginine (Arg), is able to exert a control over the size of MNPs produced in water and at room temperature. This control occurs through the stabilization of the magnetite nuclei by the ...