An amperometric bienzymatic cholesterol biosensor based on functionalized graphene modified electrode and its electrocatalytic activity towards total cholesterol determination

► ChOx and ChEt have been covalently immobilized onto functionalized graphene modified electrode. ► A well defined redox peak was observed, corresponding to the DET of the FAD/FADH2 of ChOx. ► For the free cholesterol determination, ChOx-FG/Gr electrode exhibits a sensitive response from 50 to 350 μM. ► For total cholesterol determination, (ChEt/ChOx)-FG/Gr electrode showed a linear range from 50 to 300 μM. ► Some common interferents like glucose, AA and UA did not cause any interference.