Phase controlled one-pot synthesis of heterostructured FePt-Fe₃O₄ nanocubes with excellent biocompatibility

We demonstrated a simple one-pot synthesis approach for the controlled composition of homogeneous FePt and phase-controlled heterostructured FePt/Fe₃O₄ nanocubes (NCs) utilizing 1,2-hexadecanediol and 1-octadecene as the reducing agents, respectively. When the Fe : Pt precursor ratio was varied from 1 : 1 to 4 : 1 and 1,2-hexadecanediol was utilized as the reducing agent, homogeneous FePt NCs were formed, whereas the heterostructures of FePt/Fe₃O₄ NCs were obtained when utilizing 1-octadecene as the reducing agent at Fe : Pt ratio of 4 : 1. The initial domination of nucleation of Pt-rich species and the subsequent deposition of Fe atoms leads to the formation of homogeneous FePt NCs. Heterostructured FePt/Fe₃O₄ NCs were obtained by the initial FePt seed formation, which was then followed by the heterogeneous growth of Fe₃O₄. The heterostructured FePt/Fe₃O₄ NCs exhibited two phases, i.e., FePt phase with a (111) facet of the fcc and Fe₃O₄ phase with an inverse cubic spinel structure. Moreover, both the FePt and the FePt/Fe₃O₄ NCs demonstrated almost negligible coercivity, which confirmed a typical superparamagnetic behavior. Furthermore, the cell viability tests of the FePt and FePt/Fe₃O₄ NCs demonstrated excellent biocompatibilities. Hence, the NCs could be useful for various biomedical applications, including MRI contrast agents, hyperthermia, and as a label in magnetic biochips.