Imaging Single Bacterial Cells with Electro-optical Impedance Microscopy

Fenni Zhang, Shaopeng Wang, Yunze Yang, Jiapei Jiang, Nongjian Tao

Research output: Contribution to journalArticlepeer-review

Abstract

Impedance measurements have been an important tool for biosensor applications, including protein detection, DNA quantification, and cell study. We present here an electro-optical impedance microscopy (EIM) based on the dependence of surface optical transmission on local surface charge density for single bacteria impedance imaging. We applied a potential modulation to bacteria placed on an indium tin oxide-coated slide and simultaneously recorded a sequence of transmitted microscopy images. By performing fast Fourier transform analysis on the image sequences, we obtained the DC component (signal at 0 Hz) for cell morphology imaging and the AC component (signal at the modulation frequency) for the mapping of cell impedance responses with subcellular resolution for the first time. Using this method, we have monitored the viability of Escherichia coli bacterial cells under treatment with two different classes of antibiotics with low-frequency potential modulation. The results showed that the impedance response is sensitive to the antibiotic that targets the bacterial cell membrane as the membrane capacitance dominated at low-frequency modulation. Heterogeneous responses to the antibiotic treatment were observed at a single bacteria level. In addition to the high spatial resolution, EIM is label-free and simple and can be potentially used for the continuous mapping of single bacteria impedance changes under different conditions.

Original languageEnglish (US)
Pages (from-to)348-354
Number of pages7
JournalACS sensors
Volume6
Issue number2
DOIs
StatePublished - Feb 26 2021
Externally publishedYes

Keywords

  • cell viability
  • label-free detection
  • optical imaging
  • potential modulation
  • single bacteria impedance

ASJC Scopus subject areas

  • Bioengineering
  • Instrumentation
  • Process Chemistry and Technology
  • Fluid Flow and Transfer Processes

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