Potassium and sodium measurements at clinical concentrations using phase-modulation fluorometry.

Area of Science:

• Analytical Chemistry
• Biomedical Sensing

Background:

• Accurate measurement of blood electrolytes like sodium and potassium is crucial for clinical diagnostics.
• Existing methods can face challenges with interference from other ions in complex biological samples.

Purpose of the Study:

• To investigate the feasibility of using lifetime-based sensing and phase-modulation fluorometry for measuring sodium and potassium concentrations in whole blood.
• To evaluate the performance of fluorescent probes SBFO, CD222, and PBFI under physiological conditions.

Main Methods:

• Utilized phase-modulation fluorometry and lifetime-based sensing to analyze fluorescent probes.
• Tested probes SBFO, CD222, and PBFI with varying concentrations of sodium and potassium relevant to whole blood and blood serum.
• Assessed probe responses for selectivity and interference from co-existing ions.

Main Results:

• The SBFO probe showed selective phase/modulation changes for sodium (around 100 mM) with minimal potassium interference.
• CD222 and PBFI demonstrated minor lifetime changes with physiological sodium levels, allowing for potassium measurement using lifetime-based sensing.
• The presence of sodium shifted the apparent potassium dissociation constants for CD222 and PBFI into the physiological range.

Conclusions:

• Lifetime-based sensing is a viable method for measuring sodium and potassium concentrations in whole blood.
• Fluorescent probes CD222 and PBFI, when used with lifetime-based sensing, can effectively measure blood potassium in the presence of physiological sodium levels.
• This approach offers a promising non-interfering method for monitoring extracellular cation concentrations in blood.