Detection of Bacterial Metabolic Volatile Indole Using a Graphene-Based Field-Effect Transistor Biosensor.

Zihong Lin,Ling Zhao,King Wai Chiu Lai,Guangfu Wu

doi:10.3390/nano11051155

Zihong Lin, Ling Zhao + Show 2 more

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https://doi.org/10.3390/nano11051155

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Journal: Nanomaterials	Publication Date: Apr 28, 2021
Citations: 17	License type: CC BY 4.0

Affiliation: City University of Hong Kong

Abstract

The existence of bacteria is a great threat to food safety. Volatile compounds secreted by bacteria during their metabolic process can be dissected to evaluate bacterial contamination. Indole, as a major volatile molecule released by Escherichia coli (E. coli), was chosen to examine the presence of E. coli in this research. In this work, a graphene field-effect transistor (G-FET) was employed to detect the volatile molecule-indole based on a π-π stacking interaction between the indole and the graphene. The exposure of G-FET devices to the indole provokes a change in electrical signal, which is ascribed to the adsorption of the indole molecule onto the graphene surface via π-π stacking. The adsorption of the indole causes a charge rearrangement of the graphene-indole complex, which leads to changes in the electrical signal of G-FET biosensors with a different indole concentration. Currently, the indole biosensor can detect indole from 10 ppb to 250 ppb and reach a limit of detection of 10 ppb for indole solution detection. We believe that our detection strategy for detecting bacterial metabolic gas molecules will pave a way to developing an effective platform for bacteria detection in food safety monitoring.

Highlights

We developed an indole detector using a graphene field-effect transistor (G-FET) biosensor to detect the volatile organic compounds (VOCs) and metabolic indole molecules produced by E.coli. using a portable electronic device based on olfactory, graphene-based field-effect transistors (G-FET) that can generate electrical signals during the detection process
We presented a G-FET biosensor that enables the label-free detection of the indole molecule, which is a metabolic product of E. coli
To achieve the label-free detection of lowcharged small indole molecules, we adopted graphene as the sensing material to provide a high sensitivity in electrical measurements

Summary

Introduction

Various methods have been developed to directly or indirectly detect foodborne pathogenic bacteria [5,6,7,8] The direct methods, such as viable cell enumeration [9], the selective isolation of bacteria on commercial media [10], and immunoassays [11], can directly detect bacteria, which is often tenuous with molecular-based technologies. Using these conventional methods is time-consuming for sample pretreatment and the proliferation of pathogenic bacteria [12]

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