Prussian Blue and enzyme bulk-modified screen-printed electrodes for hydrogen peroxide and glucose determination with improved storage and operational stability Original Research Article

The addition to the carbon ink, a major component of a screen-printed electrode (SPE), of an aliquot (10%) of Prussian Blue (PB)-modified glassy carbon (PB-GC) particles, resulted in an interference free “ready to use” amperometric H2O2 sensor (Vapp=−50 mV) with a LOD of 3×10−7 mol/l and a sensitivity of 135 mA (mol l−1 cm2). A storage stability of up to 8 months and an operational stability of 3 days has been achieved making these sensors suitable for mass-production. Glucose and lysine biosensors have been assembled immobilizing glucose oxidase (Gox) and lysine oxidase (LyOx) with glutaraldehyde and Nafion® onto the PB bulk-modified electrodes. A LOD of 4×10−6 mol/l for glucose and 5×10−6 mol/l for lysine with a linear range up to 0.5 and 0.7 mmol/l, respectively, have been observed. A ready to use glucose biosensor was then developed mixing PB-modified glassy carbon (7.5%), carbon ink (87.5%) and glucose oxidase (GOx, 5%) and using the mixture for the printing step of a SPE working electrode. A LOD of 3×10−5 mol/l and a linearity range up to 6×10−3 mol/l of glucose have been achieved, together with a storage stability up to 20 weeks (at RT) and an operational stability of 1 day with 11 calibration curves performed.