Fluorescence intensity and lifetime-based cyanide sensitive probes for physiological safeguard

Area of Science:

• Analytical Chemistry
• Chemical Sensing
• Fluorescence Spectroscopy

Background:

• Cyanide is a toxic substance requiring sensitive detection methods.
• Existing fluorescent probes have limitations in detecting cyanide at physiological levels.
• Boronic acid functional groups are known for sensing saccharides.

Purpose of the Study:

• To develop and characterize novel fluorescent probes for aqueous cyanide detection.
• To investigate a new cyanide binding mechanism involving boronic acid functional groups.
• To enable fluorescence-based cyanide sensing at physiologically relevant concentrations.

Main Methods:

• Synthesis of six new fluorescent probes incorporating boronic acid moieties.
• Characterization of probe responses (intensity and lifetime changes) to cyanide.
• Determination of probe disassociation constants and comparison with control compounds.
• Evaluation of probe selectivity against interfering species like hydroxide and glucose.

Main Results:

• Six novel fluorescent probes exhibit both intensity and lifetime changes upon binding cyanide.
• The probe m-BMQBA demonstrates a ≈15-fold intensity reduction and ≈10% lifetime change at <30 µM cyanide.
• A new cyanide binding mechanism involving the boronic acid group (R-B(OH)2 to R-B-(CN)3) was utilized.
• Cyanide binding leads to significantly shorter probe lifetimes, facilitating lifetime-based sensing.
• Probes show preferential binding to cyanide and hydroxide over glucose.

Conclusions:

• The developed fluorescent probes offer a sensitive method for aqueous cyanide detection up to physiological safeguard levels.
• The boronic acid functional group provides a novel and effective mechanism for cyanide anion binding.
• Fluorescence intensity and lifetime changes enable robust cyanide sensing, with potential for real-time monitoring.
• These probes demonstrate selectivity for cyanide over glucose, suggesting utility in complex biological matrices.