Probing the Fluorescence Intermittency of Bimetallic Nanoclusters using Single-Molecule Fluorescence Spectroscopy.

Area of Science:

• Nanotechnology
• Spectroscopy
• Biophysics

Background:

• Single-molecule spectroscopy (SMS) is crucial for studying molecular dynamics and biomolecule sensing.
• Developing ultra-stable single fluorophore probes with excellent photostability is a significant challenge for single-molecule fluorescence microscopy.

Purpose of the Study:

• To investigate the photophysical properties of bimetallic gold-silver nanoclusters (AuAg NCs) compared to monometallic silver nanoclusters (Ag NCs).
• To assess the potential of AuAg NCs as superior probes for single-molecule spectroscopy.

Main Methods:

• Photon antibunching experiments were conducted to evaluate probe brightness and photostability.
• Statistical analysis of at least 100 molecules was performed to quantify photobleaching and intensity.
• Comparison of photophysical properties between AuAg28 and Ag29 nanoclusters.

Main Results:

• Bimetallic AuAg28 nanoclusters demonstrated superior photostability and brightness compared to monometallic Ag29 nanoclusters.
• AuAg28 NCs exhibited longer "on" times and shorter "off" times, indicating minimal blinking.
• Au doping in Ag29 NCs resulted in a five-fold enhancement in fluorescence intensity and high survival times up to 218 seconds.

Conclusions:

• The study highlights the exceptional photophysical properties of AuAg28 nanoclusters for single-molecule spectroscopy.
• These metal nanoclusters offer significant potential for advancing single-molecule dynamic measurements in biological systems.