Robust nonenzymatic hybrid nanoelectrocatalysts for signal amplification toward ultrasensitive electrochemical cytosensing

We have discovered that magnetic Fe₃O₄ nanoparticles exhibit an intrinsic catalytic activity toward the electrochemical reduction of small dye molecules. Metallic nanocages, which act as efficient signal amplifiers, can be attached to the surface of Fe₃O₄ beads to further enhance the catalytic electrochemical signals. The Fe ₃O₄@nanocage core-satellite hybrid nanoparticles show significantly more robust electrocatalytic activities than the enzymatic peroxidase/H₂O₂ system. We have further demonstrated that these nonenzymatic nanoelectrocatalysts can be used as signal-amplifying nanoprobes for ultrasensitive electrochemical cytosensing.