Probing DNA sequences in solution with a monomer-excimer fluorescence color change

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Accurate detection of point mutations is crucial for diagnostics and research.
• Current methods for mutation detection can be complex or require specialized equipment.
• Fluorescent probes offer a sensitive and adaptable approach for molecular detection.

Purpose of the Study:

• To develop a simple, solution-based method for detecting point mutations using fluorescently labeled oligonucleotide probes.
• To characterize the spectral changes associated with probe hybridization to target DNA.
• To optimize probe design for enhanced sensitivity in mutation detection.

Main Methods:

• Synthesis of oligodeoxynucleotide probes incorporating a pyrene fluorophore at the 3' and 5' ends.
• Utilizing a phosphoramidite derivative of deoxyribose for fluorophore attachment.
• Measuring fluorescence emission spectra of probes in solution upon hybridization to complementary and mismatched target sequences.
• Optimizing probe binding orientation and overlap for maximal spectral response.

Main Results:

• Dual pyrene-labeled probes exhibited a distinct spectral shift from blue monomer emission to green-white excimer emission upon binding to a complementary target DNA sequence.
• Optimal probe binding with partial end overlap resulted in a significant decrease in monomer emission (up to 7-fold) and a substantial increase in excimer emission (up to 40-fold).
• The method demonstrated successful application in detecting single-base point mutations in solution.

Conclusions:

• A simple and sensitive fluorescent assay for point mutation detection in solution has been developed.
• The spectral changes observed are directly correlated with the hybridization of the probes to the target sequence.
• This approach offers a promising tool for genetic analysis and molecular diagnostics.