Dual-fluorescence pH probe for bio-labelling.

Area of Science:

• Biochemistry
• Spectroscopy
• Molecular Biology

Background:

• Seminaphtorhodafluor (SNARF) dyes are crucial for pH measurements in biological systems.
• Current SNARF dyes suffer from low synthesis yield and ambiguous carboxy-group positioning, impacting pH measurement accuracy.
• The commercial mixture of 5'- and 6'-carboxy-SNARF isomers exhibits a pKa difference, questioning their reliability.

Purpose of the Study:

• To synthesize and characterize a novel SNARF dye derivative with improved specificity and labeling efficiency.
• To overcome the limitations of existing SNARF dyes regarding synthesis yield and positional ambiguity.
• To expand the application of SNARF dyes in bio-labeling and advanced imaging techniques.

Main Methods:

• Modification of the SNARF structure by replacing the dicarboxyphenyl ring with a propionate group.
• Synthesis of an ethyl-iodoacetamide derivative for efficient covalent linkage to cysteine residues.
• Spectral property evaluation of the new SNARF derivative.
• Application in fluorescence lifetime imaging (FLIM) using both lifetime-based and ratiometric methods.

Main Results:

• The new SNARF derivative demonstrates efficient covalent linkage to a cyanobacterial phytochrome via cysteine residues.
• Spectral properties of the modified SNARF dye were successfully evaluated.
• The derivative was effectively applied in fluorescence lifetime imaging, showcasing its utility in advanced microscopy.
• The modified SNARF dye offers potential for more specific and reliable pH measurements and bio-labeling.

Conclusions:

• A novel SNARF dye derivative has been successfully synthesized and characterized.
• This derivative overcomes key limitations of existing SNARF dyes, enabling efficient protein labeling.
• The new SNARF dye shows promise for improved pH sensing and advanced bio-imaging applications, particularly in fluorescence lifetime imaging.