Intracellular neutral carrier-based Ca2+ microelectrode with subnanomolar detection limit

Area of Science:

• Electrochemistry
• Biomedical Engineering
• Cellular Physiology

Background:

• Intracellular calcium (Ca2+) plays a critical role in cellular signaling and function.
• Accurate measurement of intracellular Ca2+ is essential for understanding various physiological processes.
• Existing Ca2+ microelectrodes have limitations in detection limits and selectivity.

Purpose of the Study:

• To develop and characterize a novel Ca2+-selective microelectrode with improved performance for intracellular measurements.
• To evaluate the detection limit, selectivity, and stability of the new microelectrode.
• To assess the applicability of the microelectrode in biological systems.

Main Methods:

• Fabrication of single-barrelled microelectrodes with a PVC-containing membrane phase using the ETH 129 ionophore.
• Electrochemical measurements in Ca2+ buffers with intracellular K+ background.
• Selectivity studies using mixed solutions with Na+, K+, and Mg2+.
• Evaluation of interference from inhibitors and lipophilic ions.
• In situ testing in ferret ventricular muscle cells.

Main Results:

• The ETH 129-based microelectrode demonstrated a lower detection limit (pCa = 9.2) compared to ETH 1001.
• High selectivity for Ca2+ over Na+, K+, and Mg2+ was observed.
• The electrode showed minimal interference from common inhibitors and lipophilic ions.
• Stable performance with low EMF drift was maintained for at least eight hours.
• Reproducible measurements were achieved in simulated intracellular environments and preliminary cell punctures.

Conclusions:

• The novel Ca2+-selective microelectrode based on ETH 129 offers superior performance for intracellular Ca2+ detection.
• Its high selectivity, low detection limit, and stability make it a valuable tool for physiological research.
• The microelectrode is suitable for direct application in cellular environments without significant disturbance.