Fluorophore Conjugated Silver Nanoparticles: A Time-resolved Fluorescence Correlation Spectroscopic Study.

Area of Science:

• Biophysics
• Nanotechnology
• Spectroscopy

Background:

• Fluorescence detection is crucial in biological research.
• Interactions between fluorophores and metallic nanoparticles are of growing interest.
• Metal-fluorophore interactions can lead to enhanced fluorescence or quenching.

Purpose of the Study:

• To investigate the interaction between Cy5 fluorophores and silver nanoparticles.
• To utilize Fluorescence Lifetime Correlation Spectroscopy (FLCS) for analyzing metal-fluorophore systems.
• To develop highly bright probes for biological applications.

Main Methods:

• Chemically binding single-stranded DNA to 50 nm silver nanoparticles.
• Hybridizing Cy5-labeled complementary DNA to create DNA-nanoparticle conjugates.
• Employing picosecond time-resolved Fluorescence Lifetime Correlation Spectroscopy (FLCS).

Main Results:

• Cy5-labeled silver nanoparticles showed a 15-fold increase in emission signal.
• A 5-fold decrease in fluorescence lifetime was observed for nanoparticle-bound Cy5.
• FLCS successfully separated contributions from free and metal-conjugated fluorophores.
• Lifetime measurements supported a near-field interaction mechanism.

Conclusions:

• FLCS is a powerful tool for studying single-molecule metal-fluorophore interactions.
• FLCS can resolve distinct species emitting at the same wavelength.
• Bright Cy5-DNA-Ag conjugates are promising probes for high-background biological samples.