Chimeric GFP-uracil based molecular rotor fluorophores.

Area of Science:

• Organic Chemistry
• Biophysical Chemistry
• Molecular Biology

Background:

• Green fluorescent protein (GFP) is a widely used biological marker.
• Nucleobase modifications offer opportunities for novel fluorescent probes.
• Understanding microenvironmental effects on fluorescence is crucial for probe design.

Purpose of the Study:

• To synthesize and characterize novel uracil-derived nucleobase-chromophores.
• To investigate the photophysical properties and environmental sensitivity of these analogues.
• To incorporate these probes into peptide nucleic acid (PNA) for DNA sensing applications.

Main Methods:

• Erlenmeyer azlactone synthesis followed by amination using hexamethyl disilazane (HMDS).
• Spectroscopic analysis (emission, solvatochromism) to determine photophysical properties.
• Incorporation into PNA strands and evaluation of fluorescence response upon DNA hybridization.

Main Results:

• A library of uracil analogues emitting in the green spectrum was synthesized.
• Analogues exhibited solvatochromism and viscosity-dependent fluorescence enhancement.
• Solid-state quantum yields reached approximately 0.2 with emission >500 nm.
• PNA-incorporated probes showed fluorescence turn-off with mismatches and turn-on (>3-fold) with complementary DNA.

Conclusions:

• Novel nucleobase-chromophores with tunable fluorescence properties were created.
• These probes are sensitive to their microenvironment.
• The developed PNA-DNA systems demonstrate potential for sensitive and selective nucleic acid detection.