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Optical measurements of pH using fluorescence lifetimes and phase-modulation fluorometry
1Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore 21201.
Analytical Chemistry
|July 1, 1993
Summary
New fluorescent probes, seminaphthofluoresceins (SNA-FL), seminaphthorhodafluors (SNARF), and BCE-CF, offer pH sensing. Their pH-dependent fluorescence decay times enable precise measurements in physiological conditions.
Area of Science:
- Analytical Chemistry
- Biophysical Chemistry
- Sensing Technology
Background:
- Accurate pH monitoring is crucial in biological and chemical systems.
- Existing pH sensing methods may have limitations in certain applications.
- Fluorescent probes offer potential for sensitive and specific detection.
Purpose of the Study:
- To evaluate the pH-dependent fluorescence decay times of seminaphthofluoresceins (SNA-FL), seminaphthorhodafluors (SNARF), and BCE-CF.
- To determine the suitability of these probes as lifetime-based pH sensors.
- To explore wavelength-dependent pH sensitivity for enhanced measurement precision.
Main Methods:
- Phase-modulation fluorometry was employed to measure fluorescence decay times.
- Measurements were conducted across a range of light modulation frequencies (10-300 MHz).
- Excitation and emission wavelengths were varied to assess their impact on pH sensitivity.
Main Results:
- SNA-FL, SNARF, and BCE-CF probes exhibited strong pH-dependent phase and modulation values within the physiological pH range.
- pH sensitivity was tunable by selecting specific excitation and emission wavelengths.
- Phase and modulation measurements demonstrated robustness against signal intensity fluctuations.
Conclusions:
- Seminaphthofluoresceins, seminaphthorhodafluors, and BCE-CF are effective lifetime-based pH sensors.
- Wavelength selection allows for optimized pH sensitivity and precision.
- Phase-modulation fluorometry provides a reliable method for pH sensing, insensitive to signal intensity variations.