Tracking single fluorescent particles in three dimensions via extremum seeking

Area of Science:

• Biophysics
• Nanotechnology
• Microscopy

Background:

• Tracking single fluorescent particles in 3D is crucial for understanding nanoscale biophysical phenomena.
• Existing high-precision methods often involve complex and expensive experimental setups.
• There is a need for simpler techniques compatible with standard microscopy equipment.

Purpose of the Study:

• To develop a straightforward method for 3D single fluorescent particle tracking.
• To enable precise nanoscale imaging using conventional confocal or multi-photon microscopes.
• To reduce the complexity and cost associated with advanced particle tracking.

Main Methods:

• Utilizes a standard confocal or multi-photon microscope configuration.
• Employs intensity feedback to calculate real-time position commands.
• Assumes the point spread function's maximum aligns with the particle's position for tracking.

Main Results:

• Successfully tracked a diffusing quantum dot in a hydrogel using a standard epifluorescent confocal microscope.
• Demonstrates the feasibility of the intensity feedback method for real-time particle localization.
• Achieved precise tracking without requiring specialized or complex instrumentation.

Conclusions:

• The described method offers a simplified approach to 3D single particle tracking.
• This technique can be implemented on standard microscopy platforms, increasing accessibility.
• It facilitates the study of nanometer-scale biophysical processes with reduced experimental complexity.