An inhibitory enzyme electrode for hydrogen sulfide detection

Area of Science:

• Biotechnology
• Biosensor Development
• Enzyme Kinetics

Background:

• Ascorbate oxidase (AOx) is an enzyme with potential applications in biosensing.
• Hydrogen sulfide (H2S) is a gas requiring accurate detection methods.
• Enzymatic inhibition assays offer a pathway for selective analyte detection.

Purpose of the Study:

• To develop and optimize an enzymatic biosensing system for hydrogen sulfide (H2S) detection.
• To evaluate the performance and stability of the AOx-based H2S biosensor.
• To investigate the selectivity of the biosensor against common interfering ions.

Main Methods:

• Enzyme immobilization of ascorbate oxidase (AOx) using glutaraldehyde (GA).
• Optimization of immobilization parameters (GA concentration, pH) using experimental design.
• Electrochemical detection based on the inhibition of AOx activity by H2S, monitoring oxygen concentration changes.

Main Results:

• Optimized immobilization at 12.5% GA and pH 7 yielded a steady-state reaction in 55 s.
• A linear correlation was established between decreased oxygen concentration and H2S levels (1-15 mg/L).
• The biosensor showed high selectivity, with minimal interference from Fe(3+) and SO4(-2) ions (11% error).
• The enzyme electrode retained 73% of its original sensitivity after operational stability testing.
• The system achieved a low detection limit for H2S as low as 0.5 mg/L.

Conclusions:

• The developed AOx-based biosensor is effective for hydrogen sulfide detection.
• The biosensor exhibits good operational stability, selectivity, and a low detection limit.
• This enzymatic system offers a promising approach for H2S monitoring in various applications.