Anapole-Assisted Low-Power Optical Trapping of Nanoscale Extracellular Vesicles and Particles

Area of Science:

• Physics, Optics
• Biotechnology
• Materials Science

Background:

• Optical tweezers are limited for nanoscale particle manipulation due to the diffraction limit.
• Photothermal heating from lasers can damage delicate biological samples.
• Existing methods struggle to trap particles smaller than ~200 nm.

Purpose of the Study:

• To develop a method for trapping nanoscale biological particles without photothermal heating.
• To overcome the diffraction limit in optical trapping.
• To enable precise manipulation of nanoparticles for biological applications.

Main Methods:

• Utilized all-dielectric nanoantenna systems on distributed Bragg reflector substrates.
• Engineered optical anapole states to generate strong optical gradient forces.
• Focused electromagnetic energy to nanoscale dimensions (as small as 30 nm).

Main Results:

• Achieved nanoscale optical trapping with negligible temperature rise (< 1 K).
• Successfully trapped nanosized extracellular vesicles and supermeres (~25 nm).
• Used low laser power (10.8 mW) for efficient trapping.

Conclusions:

• The developed nanoscale optical trapping platform overcomes key limitations of conventional optical tweezers.
• This technique offers a promising tool for single molecule analysis and manipulation of nanoscale biological entities.
• The method minimizes photothermal degradation, preserving sample integrity.