Thin film bienzyme amperometric biosensors based on polymeric redox mediators with electrostatic bipolar protecting layer

Amperometric bienzyme sensors were constructed based on solid graphite electrodes modified with polymer redox mediator, horseradish peroxidase and a variety of oxidases and covered with a bipolar electrostatic protective layer. Glucose, ethanol, choline, glycero-3-phosphate and cholesterol sensors were designed and operated at 0 mV vs. AgAgCl using single potential step chronoamperometry. The protection of the sensor against interference from ascorbic acid and linearity of response were provided by a bipolar electrostatic layer. Sensitivities as high as 0.74 μA cm−2 mM−1 of glucose, 0.71 μA cm−2 mM−1 of ethanol 5.7 μA cm2 mM−1 of glycerol-1-phosphate, and 28.3 nA cm−2 per 10 μM of choline, were achieved.