Development of biosensor for phenolic compounds containing PPO in β-cyclodextrin modified support and iridium nanoparticles

A biosensor based on the iridium nanoparticles dispersed in ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (Ir-BMI·PF6) and a celery (Apium graveolens) extract as a source of polyphenol oxidase (PPO) was constructed. A modified support based on β-cyclodextrin (β-CDEP) was used for enzyme immobilization. The behavior of phenolic compounds was investigated by square-wave voltammetry and rutin was selected by presenting the greatest signal. The best performance was obtained with a composition of 70:10:10:10% (w/w/w/w) of the graphite powder:β-CDEP:Nujol:Ir-BMI·PF6 composition, a PPO concentration of 500 units mL−1, in 0.1 M phosphate buffer solution (pH 6.0) with frequency, pulse amplitude and scan increment at 100 Hz, 60 mV, and 3.0 mV, respectively. Under optimized conditions, the cathodic currents increased linearly for the rutin concentration range of 1.3 × 10−7–2.0 × 10−6 M with a detection limit of 7.9 × 10−8 M. This sensor demonstrated acceptable repeatability and reproducibility and the results for the rutin recovery ranged from 92.8 to 103.4%. A relative error of 0.7% was obtained in the rutin determination in simulated samples.

A biosensor based on the iridium nanoparticles dispersed in ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (Ir-BMI·PF6) and a celery extract as a source of polyphenol oxidase (PPO) was constructed. The PPO was immobilized on a support based on β-cyclodextrin, the behavior of phenolic compounds was investigated by square-wave voltammetry and rutin was selected by presenting the greatest signal. The enzyme catalyzed the oxidation of rutin to quinone and this product was electrochemically reduced to rutin on the biosensor surface at a potential of +0.28 V vs. Ag/AgCl.Figure optionsDownload as PowerPoint slideHighlights
► Biosensor based on the iridium nanoparticles and polyphenol oxidase was constructed.
► The enzyme was immobilized on a support based on β-cyclodextrin.
► The behavior of phenolic compounds was investigated by square-wave voltammetry.
► The enzyme catalyzed the oxidation of rutin to quinone.
► This product was electrochemically reduced to rutin on the biosensor surface.