Iranian Researchers Develop Smart Chip for Visual Detection of Bacteria

Wednesday, August 12, 2020 - 09:41

Researchers of Sharif University of Technology in cooperation with Universitat Autònoma de Barcelona (UAB) have developed a smart chip for visual detection of bacteria by using the electrochromic properties of polyaniline.

According to an ISCA report, finding fast and reliable ways to detect pathogenic bacteria is crucial for addressing serious public health issues in clinical, environmental, and food settings.

Based on the research, researchers 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), researchers 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.

The research has been carried out by Saba Ranjbar, Mohammad Amin Farahmand Nejad, Claudio Parolo, Saeed Shahrokhian and Arben Merkoçi.



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