One-Step Electrodeposition of Gold-Graphene Nanocomposite forConstruction of Cholesterol Biosensor

The determination of cholesterol is increasingly important for the fact that high serum cholesterol level was related with many diseases. In this work, a new cholesterol biosensor was developed based on the gold-graphene nanocomposite material prepared by one-step electrodeposition. The nanomaterial formed on a glassy carbon electrode was proved by scanning electron microscope and the electrochemical behavior of the modified electrode as well as the cyclic voltametry and electrochemical impedance spectroscopy of the ferricyanide/ferrocyanide couple. After the immobilizing of cholesterol oxidase cross-linked with chitosan, a simple cholesterol biosensor was prepared. The biosensor responded linearly to cholesterol in the concentration range of 0.25 to 5.0 mM with a detection limit of 50 μM. The sensor has the advantages of easy preparation, short response time and good selectivity. Thus, it could be used to determine the free cholesterol in serum.