Iron and iron-oxide magnetic nanoparticles as signal-amplification elements in electrochemical biosensing

• Recent advances in bio/immune sensing based on iron magnetic nanoparticles.
• Electroanalytical application of iron magnetic nanoparticles in bio/immune sensing.
• Recent developments of electrochemical biosensors using iron magnetic nanoparticles.
• Research opportunities and future development trends in iron magnetic nanoparticles.

Growing demands for ultrasensitive biosensing have led to the development of numerous signal-amplification strategies. Based on their unique properties (i.e., electro-conductivity, bio-compatibility and ease of synthesis), various iron magnetic nanoparticles (MNPs) have proved to be an excellent nanomaterial for applications in electrochemical biosensing. This review shows how iron MNPs have made significant contributions in the development of electrochemical nanobiosensors, including immuno-, enzyme, DNA and aptamer types. More importantly, we discuss in detail different aspects of the electrochemical biosensors (e.g., modes of magnetic particles, detection techniques, analytes and the corresponding sensitivity and sample matrix, and several prominent characteristics). Accordingly, we discuss research opportunities and future development trends in these areas.