Dual lifetime referencing as applied to a chloride optical sensor

Area of Science:

• Analytical Chemistry
• Materials Science
• Biomedical Engineering

Background:

• Chloride ion detection is crucial in various fields, including environmental monitoring and clinical diagnostics.
• Existing chloride sensors often face limitations in sensitivity, selectivity, or response time.
• Development of robust and responsive optical sensors for chloride remains an active area of research.

Purpose of the Study:

• To develop a novel optical sensor membrane for sensitive and selective chloride detection.
• To utilize two luminophores with different decay times for enhanced signal transduction.
• To enable chloride quantification through a measurable fluorescence phase shift.

Main Methods:

• Fabrication of a hydrogel membrane incorporating a chloride-insensitive ruthenium complex (reference luminophore) and a chloride-quenchable fluorescent probe (lucigenin).
• Excitation of the luminophores using a blue LED with sinusoidally modulated light at approximately 45 kHz.
• Measurement of the analyte-dependent fluorescence phase shift, correlating it with chloride concentration based on the ratio of luminescence intensities.

Main Results:

• The developed membrane exhibits an optical response to chloride ions.
• A chloride-dependent fluorescence phase shift was successfully measured, dependent on the ratio of the two luminophores.
• The sensor demonstrated an adjustable dynamic range by modifying luminophore ratios or optical filters.

Conclusions:

• The developed membrane-based optical sensor provides a new method for chloride detection.
• The dual-luminophore system and phase shift measurement offer a sensitive and potentially selective approach.
• The sensor's adjustable dynamic range enhances its applicability in diverse chloride sensing scenarios.