Enzyme-modified indium tin oxide microelectrode array-based electrochemical uric acid biosensor

Area of Science:

• Electrochemistry
• Biosensor Technology
• Materials Science

Background:

• Uric acid is a key biomarker for several diseases.
• Miniaturized biosensors are crucial for point-of-care diagnostics.
• Indium tin oxide (ITO) microelectrode arrays offer advantages for sensor fabrication.

Purpose of the Study:

• To develop a miniaturized electrochemical biosensor for uric acid detection.
• To immobilize uricase enzyme onto an ITO microelectrode array for enhanced performance.
• To characterize the biosensor's performance under microfluidic conditions.

Main Methods:

• Fabrication of a miniaturized electrochemical biosensor using 3-aminopropyltriethoxysilane (APTES)-modified ITO microelectrode array (μEA).
• Immobilization of uricase enzyme onto the ITO-μEA using bis[sulfosuccinimidyl]suberate (BS³) cross-linker.
• Characterization using atomic force microscopy, cyclic voltammetry, and impedance spectroscopy.
• Amperometric detection of uric acid in an aqueous solution under a polydimethylsiloxane microfluidic channel.

Main Results:

• Effective binding of uricase onto the μEA surface was confirmed by electrochemical techniques.
• The biosensor exhibited a linear response to uric acid from 0.058 to 0.71 mM.
• Achieved a sensitivity of 46.26 μA mM^-1 cm^-2 with a rapid response time of 40 seconds.
• Demonstrated good enzyme stability, retaining 85% activity for 6 weeks.

Conclusions:

• The developed miniaturized electrochemical biosensor enables sensitive and stable uric acid detection.
• The use of ITO microelectrode arrays enhances sensitivity and allows probing of the entire microfluidic channel core.
• This biosensor holds potential for efficient and low-volume sample analysis in diagnostic applications.