Measuring the size and charge of single nanoscale objects in solution using an electrostatic fluidic trap

Area of Science:

• Nanotechnology
• Colloid and Surface Science
• Physical Chemistry

Background:

• Accurate measurement of nanoscale object size and charge in solution is challenging.
• Light scattering methods are biased towards larger particles, and field-based migration techniques lack accuracy and resolution.
• Existing methods struggle with characterizing individual nanoparticles and macromolecules in dispersions.

Purpose of the Study:

• To develop a high-throughput method for direct measurement of single nanoscale object size and charge.
• To overcome the limitations of traditional techniques like light scattering and field-driven migration.
• To enable sensitive detection of molecular binding and dynamic measurements at interfaces.

Main Methods:

• Utilizing an array of electrostatic traps to confine nanoscale objects.
• Analyzing the thermal motion of individual objects within the traps.
• Applying principles analogous to the Millikan oil drop experiment for precise measurements.

Main Results:

• Demonstrated direct, high-throughput measurement of size and charge for single nanoscale objects.
• Achieved high accuracy and resolution, surpassing limitations of prior methods.
• Validated the potential for sensitive detection of molecular binding events.

Conclusions:

• The electrostatic trap array method offers a powerful new tool for nanoscale characterization.
• This technique provides a significant advancement for studying colloids, macromolecules, and interfacial phenomena.
• Future applications include sensitive molecular binding detection and single-charge resolved interfacial measurements.