Smart chip for visual detection of bacteria using the electrochromic properties of polyaniline

Ranjbar, S ; Sharif University of Technology | 2019

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  1. Type of Document: Article
  2. DOI: 10.1021/acs.analchem.9b03407
  3. Publisher: American Chemical Society , 2019
  4. Abstract:
  5. Finding fast and reliable ways to detect pathogenic bacteria is crucial for addressing serious public health issues in clinical, environmental, and food settings. Here, we present a novel assay based on the conversion of an electrochemical signal into a more convenient optical readout for the visual detection of Escherichia coli. Electropolymerizing polyaniline (PANI) on an indium tin oxide screen-printed electrode (ITO SPE), we achieved not only the desired electrochromic behavior but also a convenient way to modify the electrode surface with antibodies (taking advantage of the many amine groups of PANI). Applying a constant potential to the PANI-modified ITO SPE induces a change in their oxidation state, which in turn generates a color change on the electrode surface. The presence of E. coli on the electrode surface increases the resistance in the circuit affecting the PANI oxidation states, producing a different electrochromic response. Using this electrochromic sensor, we could measure concentrations of E. coli spanning 4 orders of magnitude with a limit of detection of 102 colony forming unit per 1 mL (CFU mL-1) by the naked eye and 101 CFU mL-1 using ImageJ software. In this work we show that merging the sensitivity of electrochemistry with the user-friendliness of an optical readout can generate a new and powerful class of biosensors, with potentially unlimited applications in a variety of fields. Copyright © 2019 American Chemical Society
  6. Keywords:
  7. Electrochemistry ; Electrochromism ; Escherichia coli ; Polyaniline ; Tin oxides ; Colony forming units ; Electrochemical signals ; Electrochromic behavior ; Electrochromic properties ; Measure concentration ; Pathogenic bacterium ; Public health issues ; Screen printed electrodes ; Electrodes
  8. Source: Analytical Chemistry ; Volume 91, Issue 23 , 2019 , Pages 14960-14966 ; 00032700 (ISSN)
  9. URL: https://pubs.acs.org/doi/abs/10.1021/acs.analchem.9b03407