Much effort is conducted to construct artificial objects that are capable of converting chemical or electromagnetic energy into a specific, predetermined motion on the nanoscale. We present results on the synthesis of core-shell nanoparticles capable to be set in rotation by the application of electromagnetic fields. The nanorotors implied in the study are based on the cobalt nanospheres decorated with a stabilizing brush shell composed of poly(epsilon-caprolactone) that is attached by surface-initiated polymerization. The functional cores used as macroinitiators can be fabricated alternatively by a two-step or a one-step process. (C) 2008 Elsevier Ltd. All rights reserved.