Nanocomposite for Construction 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 nanocompositematerial 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 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.

Graphene (GE), a new advent of carbon material with single layer of carbon atoms in a two-dimensional lattice, dominated the carbon nanomaterials for its advantages of fast electron transportation and low raw material prices. The integration of GE with noble metal nanoparticles had shown the promising applications in electrochemical biosensors. In the work of Aravind et al, the substantial effect of Au nanoparticles (AuNPs) dispersed over graphene nanoplatelets was proved. Electrodeposition is a convenient technique for preparing both GE and AuNPs. And it is suitable for the fast modification of nanomaterials on a bare electrode with good adherence and optional film structure control. Hu et al.have provided a general route for fabrication of graphene-based noble metal nanomaterials composite. The graphene sheets suspension was cast onto the surface of the pretreated GC electrode, the AuNPs were electrodeposited on the GE/GCE electrode after the evaporating of solvent. Xia et al.have fabricated AuNPs/GE modified electrode by dipping bare GCE into graphite oxide suspension and chloroauric acid solution and electrodepositing under different potential alternately for ten times.