Polymer Indicator Displacement Assay (PIDA) with Boronic Acid Receptors on Graphene Foam Electrodes for Self-Optimised Impedimetric Lactic Acid Determination

Simon M. Wikeley, Pablo Lozano-Sanchez , Marco Caffio , Tony D. James, Frank Marken

Research output: Contribution to journalArticlepeer-review

Abstract

Synthetic organic receptor molecules are employed based on boronic acids attached to graphene to provide functionality and selectivity in competitive analyte binding. Here, a new electrochemical sensor concept based on a surface redox polymer indicator displacement (avoiding traditional solution redox indicators) is proposed and demonstrated on graphene foam electrodes. A pyrene-derivatised boronic acid chemo-receptor for lactic acid is adsorbed onto graphene foam and coated with poly-nordihydroguaiaretic acid (poly-NHG) as an electrochemically active polymer indicator. When bound to the boronic acid, poly-NHG remains redox silent. Dynamic displacement with lactic acid results in a concentration-dependent Faradaic current response. Effects of pH and detection methodology (voltammetry, chronoamperometry, and impedance spectroscopy) are investigated. Self-optimised impedimetric sensing based on the interfacial electron transfer resistance is demonstrated. While lactic acid sensing in human serum is possible, the sensor response is lower. Surface-active components from human serum are shown to modify the sensor response without affecting performance. Lactic acid sensing in artificial sweat at pH 4.7 is shown to result in a Langmuirian binding curve with apparent binding constant K = 40 M-1.
Original languageEnglish
Article number133089
JournalSensors and Actuators B: Chemical
Volume377
Early online date30 Nov 2022
DOIs
Publication statusE-pub ahead of print - 30 Nov 2022

Keywords

  • Electron transfer
  • Impedance spectroscopy
  • Lactic acid
  • Serum
  • Sweat
  • Voltammetry

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

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