Real-Time Analysis of Oxygen Gradient in Oocyte Respiration Using a High-Density Microelectrode Array.

Area of Science:

• Biomedical Engineering
• Cellular Physiology
• Electrochemistry

Background:

• Oxygen concentration gradients are crucial for understanding cell metabolism.
• Current oxygen sensing methods have limitations in resolution, speed, and cost.
• Electrochemical imaging offers a potential solution for high-resolution, real-time oxygen monitoring.

Purpose of the Study:

• To present an electrochemical sensor platform with a custom CMOS-based microchip and microelectrode array (MEA) for measuring cellular oxygen consumption rate (OCR).
• To demonstrate the system's capability for real-time, 2D oxygen imaging with high spatial and temporal resolution.
• To analyze the OCR and oxygen flux density of bovine cumulus-oocytes-complexes cells.

Main Methods:

• Development of a custom CMOS-based microchip with a high-density, Pt-coated MEA (16,064 pixels over 3.6 mm x 3.6 mm).
• Utilization of a three-electrode configuration for electrochemical measurements.
• Integration of a microfluidic system for bio-sample handling and delivery.
• Real-time 2D imaging of dissolved oxygen concentration at 27.5 µm spatial and 4 Hz temporal resolution.

Main Results:

• The system successfully imaged low oxygen concentrations (down to 18.3 µM).
• Real-time 2D heatmaps visualized dissolved oxygen concentration near the MEA.
• Bovine cumulus-oocytes-complexes cells OCR and oxygen flux density were analyzed in vitro.
• Demonstrated spatial and temporal dynamics of live cell/tissue metabolism.

Conclusions:

• The developed electrochemical imaging system provides a powerful tool for real-time, high-resolution OCR analysis.
• This technology overcomes limitations of existing oxygen sensing methods, enabling deeper insights into cellular metabolism.
• The platform facilitates the study of spatial and temporal dynamics of cell metabolism in live samples.