Pyrene functionalized molecular beacon with pH-sensitive i-motif in a loop

Area of Science:

• Biophysical Chemistry
• Molecular Diagnostics
• Nanotechnology

Background:

• pH monitoring is crucial in biological and chemical systems.
• Existing sensors may lack precision or reversibility.
• Molecular beacons offer a platform for sensitive detection.

Purpose of the Study:

• To develop a novel spectral sensor for precise pH detection.
• To combine i-motif DNA structural changes with pyrene fluorescence.
• To demonstrate the sensor's reversible and high-resolution performance.

Main Methods:

• Spectral characterization of a pH-sensitive molecular beacon.
• Utilizing pyrene excimer formation as a fluorescence signal.
• Employing pH-dependent i-motif formation in DNA hairpin loops.
• Performing repeated pH cycling experiments between 7.5±0.3 and 6.5±0.3.

Main Results:

• The sensor exhibits pH-dependent fluorescence switching based on i-motif formation.
• Pyrene excimer production is directly linked to i-motif stability.
• The system demonstrated reversible operation across multiple pH cycles.
• Achieved high pH resolution (0.1 pH unit) within a narrow pH range (1.5 pH units).

Conclusions:

• The developed system is a highly sensitive and reversible spectral pH sensor.
• This approach integrates DNA nanostructure dynamics with fluorescence reporting.
• The sensor shows potential for precise pH monitoring in various applications.