A General Strategy Toward pH-Resistant Phenolic Fluorophores for High-Fidelity Sensing and Bioimaging Applications

Area of Science:

• Chemical Biology
• Biophotonics
• Fluorescence Imaging

Background:

• Phenolic fluorophores are valuable for bioimaging but exhibit pH-dependent fluorescence.
• This pH sensitivity limits their application in biological systems where pH varies.
• Existing research has largely overlooked the need for pH-resistant phenolic fluorophores.

Purpose of the Study:

• To develop a straightforward method for creating pH-resistant phenolic fluorophores.
• To enhance the photophysical properties of existing fluorophores for bioimaging.
• To demonstrate the utility of these modified fluorophores in cellular and tissue imaging.

Main Methods:

• Introduced a hydrogen-bonding acceptor (e.g., morpholine) adjacent to the phenolic hydroxyl group.
• Synthesized modified phenolic fluorophore derivatives.
• Evaluated photophysical properties including emission spectra, stability, and pH resistance.
• Performed ratiometric imaging experiments on cells and tissues.

Main Results:

• The structural modification successfully rendered phenolic fluorophores pH-resistant and "medium-resistant".
• Modified dyes exhibited bathochromic emission shifts, increased Stokes shifts, and enhanced photostability.
• Fluorescence intensity was significantly improved in the modified derivatives.
• Ratiometric imaging in cells and tissues demonstrated reliable performance.

Conclusions:

• A simple structural modification can convert conventional phenolic fluorophores into robust, pH-resistant imaging agents.
• This strategy expands the toolkit of fluorophores available for accurate and reliable bioimaging.
• The enhanced properties facilitate advanced applications like ratiometric imaging in complex biological environments.