Low-potential amperometric enzyme biosensor for xanthine and hypoxanthine.

Area of Science:

• Biochemistry
• Electrochemistry
• Biosensor Technology

Background:

• Bacterial xanthine dehydrogenase (XDH) plays a crucial role in purine metabolism.
• Developing sensitive and selective biosensors for metabolites like xanthine is important for various applications.
• Electrochemical biosensors offer advantages in terms of sensitivity, selectivity, and potential for miniaturization.

Purpose of the Study:

• To construct and optimize an electrochemical biosensor for hypoxanthine and xanthine detection.
• To immobilize bacterial xanthine dehydrogenase (XDH) from Rhodobacter capsulatus onto an edge-plane pyrolytic graphite (EPG) electrode.
• To evaluate the performance of the developed biosensor, including its sensitivity, linearity, and detection limit.

Main Methods:

• Immobilization of bacterial xanthine dehydrogenase (XDH) onto an edge-plane pyrolytic graphite (EPG) electrode.
• Utilizing phenazine methosulfate (PMS) as a mediator for electron transfer.
• Optimization of the electrochemical biosensor by adjusting applied potential and pH.
• Characterization of the biosensor response to xanthine using controlled potential amperometry.

Main Results:

• The developed biosensor successfully detected xanthine at physiological pH.
• The electrocatalytic oxidation response of the biosensor showed a linear relationship with xanthine concentration from 1.0 × 10(-5) to 1.8 × 10(-3) M (R² = 0.994).
• A very low detection limit for xanthine of 0.25 nM was achieved.

Conclusions:

• The immobilized XDH/EPG electrode functions as an effective electrochemical biosensor for xanthine.
• The biosensor exhibits high sensitivity and a wide linear range for xanthine detection.
• This technology holds promise for the sensitive detection of xanthine in various biological and environmental samples.