Pyrene excimer signaling molecular beacons for probing nucleic acids

Area of Science:

• Biochemistry
• Molecular Biology
• Analytical Chemistry

Background:

• Molecular beacons (MBs) are DNA probes used for sequence detection.
• Traditional MBs often rely on single fluorophore-quencher pairs.
• Improving sensitivity and signal output in MBs is an ongoing research area.

Purpose of the Study:

• To engineer and evaluate novel molecular beacons utilizing multiple pyrene monomers for enhanced DNA detection.
• To investigate the relationship between the number of pyrene monomers and the resulting fluorescence signal.
• To assess the performance of these probes in different detection environments.

Main Methods:

• Design and synthesis of MBs with 1-4 pyrene monomers at the 5' end and DABCYL quencher at the 3' end.
• Steady-state and time-resolved fluorescence spectroscopy to measure probe performance.
• Assays conducted in buffer and cell-growth media to determine limits of detection.

Main Results:

• MBs exhibited quenched excimer fluorescence in a closed-stem conformation and strong emission in an open-stem conformation upon target binding.
• Subnanomolar detection limits were achieved in buffer using steady-state assays.
• Low-nanomolar detection was achieved in cell-growth media using time-resolved signaling.
• Increasing pyrene monomers enhanced excimer emission intensity, quantum yield, and excited-state lifetime.

Conclusions:

• Multiple-pyrene labeled MBs provide a sensitive and scalable platform for real-time DNA detection.
• The pyrene excimer moiety offers a robust alternative to conventional fluorophores in nucleic acid probes.
• This approach demonstrates potential for advanced molecular diagnostics and biological research.