Ultra-stable biosensor transducer for continuous monitoring

Prussian Blue (PB), being the most active and selective hydrogen peroxide transducer and allowing H₂O₂ detection by its reduction in the presence of oxygen, suffers from solubilization by the product of electrode reaction, hydroxyl ion (OH‾). Stabilization of the transducer is possible with isostructural nickel hexacyanoferrate (NiHCF). Herewith we report on the new composite PB-NiHCF material synthesized, which is noticed by SEM imaging. Reliable calibration-free H₂O₂ monitoring with the corresponding modified electrode is up to 100 times longer than in case of pure PB and up to 10 times – than with the electrodes stabilized through layer-by-layer assembly. The PB-NiHCF composite film displays operational stability, which is even higher as compared to the stabilizer itself (NiHCF thick film, 30 nmol cm⁻²), but is characterized by the activity close to it of pure Prussian Blue. The corresponding biosensor is completely stable during 3 days of continuous glucose (5 mM) monitoring. The reported ultra-stable and highly sensitive transducer would provide reliable continuous monitoring of low-molecular weight metabolites.