Glucose oxidase, lactate oxidase, and galactose oxidase enzyme electrode based on polypyrrole with polyanion/PEG/enzyme conjugate dopant

In this study, glucose, lactate, and galactose biosensors were synthesized using polypyrrole with a polyanion/PEG/enzyme conjugate dopant. Glucose oxidase (GOD), lactate oxidase (LOD), and galactose oxidase (GAO) were successfully conjugated to the polyanion via a poly(ethylene glycol) (PEG) spacer, and more than 75% of their bioactivities were preserved. The efficiency of enzyme immobilization on the electrode was investigated based on the electropolymerizability of polypyrrole with the conjugated enzyme dopants. The enzyme incorporation into the polypyrrole matrix was effective regardless of whether the net surface charge of enzymes was positive or negative. The GOD electrode showed linearity up to 26 mM glucose with a sensitivity of 217 nA mM−1 cm−2. The LOD electrode linearly responded to lactate concentrations up to 12 mM with a sensitivity of 151 nA mM−1 cm−2. The amperometric response of the GAO electrodes to the galactose concentration was linear in the range of 0–24 mM with a sensitivity of 106 nA mM−1 cm−2. In all enzyme electrodes, the response time was less than 40 s.