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Bright NIR-Emitting Styryl Pyridinium Dyes with Large Stokes' Shift for Sensing Applications
Nirasha I Wickramasinghe1, Brian Corbin2, Devni Y Kanakarathna1
1Department of Chemistry, Faculty of Science, University of Colombo, Colombo 00300, Sri Lanka.
Biosensors
|August 25, 2023
Summary
Two new near-infrared emitting dyes were synthesized and show sensitivity to their environment. These probes effectively visualize bacteria and yeast using fluorescence microscopy.
Area of Science:
- Organic Chemistry
- Photophysics
- Materials Science
Background:
- Donor-π-acceptor (D-π-A) dyes are crucial for optoelectronic applications.
- Developing novel near-infrared (NIR) emitting probes with high sensitivity is essential for advanced imaging.
- Regioisomerism in D-π-A systems can significantly influence photophysical properties.
Purpose of the Study:
- Synthesize and characterize two NIR-emitting D-π-A type regioisomeric styryl pyridinium dyes (1a-1b).
- Investigate their photophysical properties, including excitation-emission wavelengths, quantum yields, and Stokes' shifts.
- Evaluate their environmental sensitivity and potential for biological imaging.
Main Methods:
- Synthesis of regioisomeric styryl pyridinium dyes (1a-1b).
- Spectroscopic analysis (UV-Vis absorption and fluorescence emission) under varying environmental conditions (polarity, viscosity, temperature, concentration).
- Fluorescence microscopy for visualizing bacteria (Bacillus megaterium, Escherichia coli) and yeast (Saccharomyces cerevisiae).
Main Results:
- The synthesized dyes (1a-1b) exhibit NIR emission (690-720 nm) with high fluorescence quantum yields (0.24-0.72) and large Stokes' shifts (150-240 nm).
- Both probes demonstrate significant environmental sensitivity, with noticeable changes in optical properties in response to polarity, viscosity, temperature, and concentration.
- Regioisomer 1b shows a bathochromic shift compared to 1a due to the regio-effect, indicating tunable properties.
- Excellent performance in visualizing bacteria and yeast via fluorescence microscopy was observed.
Conclusions:
- The synthesized regioisomeric styryl pyridinium dyes are promising NIR emitters with tunable photophysical properties.
- Their high environmental sensitivity makes them suitable for sensing applications.
- These probes demonstrate excellent potential for bioimaging of microorganisms like bacteria and yeast.
