Single unlabeled protein detection on individual plasmonic nanoparticles

Area of Science:

• Analytical Chemistry
• Molecular Biology
• Biophysics

Background:

• The detection limit in analytical chemistry and biology is the single molecule.
• Current methods like fluorescent dye labels or enzymatic amplification require analyte labeling, which can alter biological processes.
• There is a need for methods that can detect and study single molecules without modification.

Purpose of the Study:

• To develop a technique for detecting single, unlabeled proteins.
• To achieve extremely high temporal resolution for observing molecular events.
• To enable the study of dynamic processes at the single-molecule level.

Main Methods:

• Utilizing single gold nanoparticles as probes.
• Detecting unlabeled proteins with high temporal resolution (millisecond scale).
• Monitoring single protein binding events and equilibrium coverage fluctuations.

Main Results:

• Successful detection of single unlabeled proteins.
• Observation of single protein binding events on a millisecond time scale.
• Resolution of equilibrium coverage fluctuations, providing insights into Brownian dynamics.

Conclusions:

• The developed method enables the study of unlabeled macromolecules at the single-molecule level.
• This technique opens new avenues for investigating protein folding dynamics, adsorption processes, and nonequilibrium soft matter dynamics.
• It offers a powerful tool for advancing fundamental understanding in chemistry and biology.