One-step solid-phase synthesis of ultrasmall homogeneous face-centered tetragonal FePt nanoparticles encapsulated in thin carbon shells

Discrete, homogenous and ultrasmall (mostly 2-4 nm) L1(0)-ordered fct FePt nanoparticles encapsulated in well-graphitized thin carbon shells have been prepared by a one-step solid-phase synthesis technique, which can be applied for the production of a number of metal alloy nanoparticles encapsulated in carbon shells. The as-synthesized FePt@C nanoparticles of size 2.1 +/- 0.4 nm present superparamagnetic properties at room temperature. The 3.3 +/- 0.6 nm size FePt@C nanoparticles have a high coercivity, up to 4.56 kOe at room temperature, and superior chemical stability in a high concentration HCl (10 M) solution. Furthermore, these nanoparticles functionalized non-covalently by phospholipid-poly(ethylene) glycol show biocompatibility with the tested cells (mouse macrophage and mouse L929 fibroblasts cells) in all test concentrations (0.025-0.2 mg mL(-1)).