A Flow-Through Biosensor System Based on Pillar[3]Arene[2]Quinone and Ferrocene for Determination of Hydrogen Peroxide and Uric Acid

Simple and reliable electrochemical sensors are highly demanded in medicine and pharmacy for the fast determination of metabolites and biomarkers of diseases. In this work, a flow-through biosensor system was developed on the base of a screen-printed carbon electrode modified with pillar[3]arene[2]quinone and ferrocene implemented in carbon black. The modification was performed in a single step and resulted in the formation of a stable layer with good operation characteristics. Uricase was immobilized on the inner walls of a replaceable reactor by carbodiimide binding. A flow-through cell was manufactured by 3D printing from poly(lactic acid). The flow-through system was first optimized on the hydrogen peroxide assay and then used for the determination of 1 nM–0.1 mM uric acid (limit of detection 0.3 nM, 20 measurements per hour). Implementation of ferrocene resulted in a synergetic increase in the cathodic current of H₂O₂ reduction measured by flow switching in chronoamperometric mode. The developed system was tested on the determination of uric acid in artificial urine and Ringer–Locke solution and showed a recovery rate of 96–112%. In addition, the possibility of determination of H₂O₂ in commercial disinfectants was shown. Easy assembly, fast and reliable signal and low consumption of the reagents make the system developed attractive for routine clinical analysis of metabolites.