Title of Paper:High-frequency, dielectric spectroscopy for the detection of electrophysiological/biophysical differences in different bacteria types and concentrations

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Date of Publication:2018-10-22

Journal:ANALYTICA CHIMICA ACTA

Included Journals:PubMed、SCIE

Volume:1028

Page Number:86-95

ISSN No.:0003-2670

Key Words:Dielectric spectroscopy; Complex permittivity; Bacterial monitoring; Biophycial; Pathogen monitoring

Abstract:This paper describes a novel technique to quantify and identify bacterial cultures of Bacillus Subtilis (2.10 -1.30 x 10(9) CFU mL(-1)) and Escherichia Coli (1.60-1.00 x 10(9) CFU mL(-1)), in corn oil using dielectric spectroscopy at elevated frequencies of 0.0100-20.0 GHz. This technique is using the electrophysiological/biophysical differences (e.g. gram positive and gram negative) between various bacteria types, as a basis to distinguish between bacteria concentrations and bacteria types. A close-ended, coaxial probe of 20.0 mm long sample-holder was developed and used to calculate the dielectric constant from the measured S parameters of the bacterial cultures, using the Nicolson-Ross-Weir method. This technique shows a linear relationship (r(2) >= 0.999) between the dielectric constant and the cell concentration, at 16.0 GHz. The sensitivity of the technique is 0.177 x 10(9) (CFU mL(-1))(-1) for B. Subtilis (with a size of 10.0 x 1.00 mu m), 0.322 x 10(9) (CFU mL(-1))(-1) for E. Coli (with a size of 2.00 x 0.500 mu m) and 0.913 x 10(9) (CFU mL(-1))(-1) for their 1:1 mixture, while the response time is 60.0s. The dependency of dielectric constant on the bacterial cell concentration at a given frequency can be potentially exploited for measuring bacterial concentrations and biophysical differences. (C) 2018 Elsevier B.V. All rights reserved.