Potentiometric vs amperometric sensing of glycerol using glycerol dehydrogenase immobilized via layer-by-layer self-assembly

An electrochemical biosensor for glycerol was obtained by using a novel concatenation of molecules to immobilize glycerol dehydrogenase (GlDH) on a gold electrode via layer-by-layer (LBL) self-assembly. The surface of the enzyme electrodes was characterized by cyclic voltammetry and scanning electron microscopy which confirmed the attachment of enzyme on the gold electrode with the assistance of the tethering molecules. The biosensor was assessed for its potentiometric and amperometric response to glycerol in the presence of the enzyme stimulants, ammonium sulfate and manganese chloride. The electrodes demonstrated good selectivity and reproducibility, with a amperometric response at a working voltage of 1.3 V in the 0.001 to 1 M glycerol concentration range, a 12.07 mu A center dot M-1 sensitivity, and a 6.8 mu M lower limit of detection. The average diffusion coefficient of glycerol is 8.63 x 10(-6) cm(2)s(-1) as determined by chronoamperometry.