Platinum-catalyzed enzyme electrodes immobilized on gold using self-assembled layers

Area of Science:

• Electrochemistry
• Biosensor Technology
• Surface Chemistry

Background:

• Enzyme immobilization on electrode surfaces is crucial for biosensor development.
• Self-assembled monolayers (SAMs) provide a versatile platform for controlled enzyme attachment.
• Gold electrodes are widely used due to their favorable electrochemical properties.

Purpose of the Study:

• To develop an enzyme biosensor for glucose detection using self-assembled monolayers (SAMs) on gold electrodes.
• To investigate two methods for glucose oxidase immobilization and detection.
• To compare the performance of biosensors fabricated on bulk versus thin-film gold electrodes.

Main Methods:

• Enzyme immobilization via carbodiimide coupling of glucose oxidase to a 3-mercaptopropionic acid SAM.
• Amperometric detection using a p-benzoquinone mediator.
• Direct detection of hydrogen peroxide via platinization of the enzyme-SAM electrode.
• Fabrication and performance evaluation on bulk and thin-film gold electrodes.

Main Results:

• The glucose oxidase-SAM biosensor demonstrated good sensitivity and a large dynamic range with a p-benzoquinone mediator.
• Direct detection of hydrogen peroxide was achieved after platinization, eliminating the need for a redox mediator.
• Significant differences in sensitivity were observed between biosensors constructed on bulk and thin-film gold electrodes.

Conclusions:

• Enzyme biosensors can be effectively constructed using SAMs on gold electrodes.
• The choice of electrode surface (bulk vs. thin-film gold) critically influences biosensor performance and sensitivity.
• Direct electrochemical detection of reaction products is feasible, simplifying biosensor design.