Nanoporous gold-based microbial biosensor for direct determination of sulfide

Area of Science:

• Environmental Science
• Biotechnology
• Electrochemistry

Background:

• Sulfide pollution poses significant environmental and public health risks.
• Existing sulfide detection methods lack sensitivity, selectivity, or simplicity.
• There is a critical need for advanced analytical tools for environmental monitoring.

Purpose of the Study:

• To develop a novel microbial biosensor for sensitive and selective sulfide detection.
• To utilize recombinant Escherichia coli BL21 (E. coli BL21) expressing sulfide:quinone oxidoreductase (SQR) for sulfide sensing.
• To engineer a robust bioelectrode for environmental applications.

Main Methods:

• Engineered E. coli BL21 cells expressing SQR were immobilized on nanoporous gold (NPG).
• The E. coli/NPG biocomposite was used to modify a glassy carbon electrode (GCE), forming the E. coli/NPG/GCE bioelectrode.
• Electrochemical techniques were employed to characterize and test the bioelectrode's performance.

Main Results:

• The E. coli/NPG/GCE bioelectrode exhibited a wide linear response range for sulfide detection (50μM to 5mM).
• High sensitivity (18.35μAmM^-1cm^-2) and a low detection limit (2.55μM) were achieved.
• The bioelectrode demonstrated superior anti-interference capabilities compared to enzyme-based sensors and was successfully applied to wastewater analysis.

Conclusions:

• The developed microbial biosensor provides a sensitive, selective, and simple method for sulfide detection.
• The co-catalytic effect of SQR and NPG enhances electrochemical performance.
• This E. coli/NPG/GCE bioelectrode shows great potential for reliable environmental monitoring and wastewater management.