▎ 摘　　要

Three different Graphene-Metallic (Graphene-Me) nanocomposites - Graphene-Silver (Graphene-Ag), Graphene-Gold (Graphene-Au) and Graphene-Platinum (Graphene-Pt) nanocomposites - were prepared and characterized. The electrochemical performances of these nanocomposites were tested by incorporating them with glassy carbon paste electrode (GCPE) and used them in biofuel cells (BFC) and as amperometric xanthine biosensor transducers. Present work contains the first application of Graphene-Au and Graphene-Ag nanocomposite in BFCs and also first application of these Graphene-Me nanocomposites in xanthine biosensors. Considering BFC, power and current densities were calculated as 2.03 mu W cm(-2) and 167.46 mu A cm-(2) for the plain BFC, 3.39 mu W cm(-2) and 182.53 mu A cm(-2) for Graphene-Ag, 4.43 mu W cm(-2) and 230.15 mu A cm(-2) for Grapehene-Au and 6.23 mu W cm(-2) and 295.23 mu A cm(-2) for Graphene-Pt nanocomposite included BFCs respectively. For the amperometric xanthine biosensor linear ranges were obtained in the concentration range between 5 mu M and 50 mu M with the RSD (n=3 for 30 mu M xanthine) value of 4.28% for plain xanthine biosensor, 3 mu M and 50 mu M with the RSD (n=3 for 30 mu M xanthine) value of 9.37% for Graphene-Ag, 5 mM to 20 mu M with the RSD (n=3 for 5 mM xanthine) value of 9.00% and 30 mu M to 70 mM with the RSD (n=3 for 30 mu M xanthine) value of 8.80% for Grapehene-Au and 1 vM and 70 with the the RSD (n=3 for 30 mu M xanthine) value of 2.59% for Grapehene-Pt based xanthine biosensors respectively.