In summary, we have demonstrated th

In summary, we have demonstrated that GO–Fe3O4 nanocomposites possess superparamagnetic properties and intrinsicperoxidase-like activity. The catalytic activity was dependent onpH, temperature, catalyst amount, and H2O2 concentration.Kinetic analysis indicated that the catalysis is in accord withtypical Michaelis–Menten kinetics and follows a ping-pongmechanism. The kinetic parameters also proved that the incorporation of Fe3O4 with GO improved the catalytic affinitytoward H2O2. On this basis, we constructed a simple, sensitiveand selective colorimetric assay to detect H2O2 and glucose inurine samples. GO–Fe3O4 nanocomposites, as novel peroxidasemimetics, show several advantages over natural enzymes andother existing alternatives, such as ease of preparation, low cost,superparamagnetic properties and enhanced affinity. Our workwill facilitate the utilization of the intrinsic peroxidase activity ofthe GO–Fe3O4 nanocomposites in medical diagnostics andbiochemistry.