Meta-amplified dark-field interferometric scattering microscopy.

Area of Science:

• Nanotechnology
• Biophysics
• Optical Microscopy

Background:

• Label-free optical detection of nanometer-scale bioparticles is crucial for noninvasive biological studies.
• Existing interferometric scattering microscopy (iSCAT) faces challenges in sensitivity and image contrast for small particles due to weak scattering signals.
• Distinguishing weak signals from background illumination remains a significant hurdle in current iSCAT methods.

Purpose of the Study:

• To introduce a novel microscopy technique, meta-amplified dark-field interferometric scattering microscopy (MAD-iSCAT), for enhanced nanoparticle detection.
• To leverage plasmonic metasurfaces to overcome the sensitivity and contrast limitations of conventional iSCAT.
• To demonstrate improved label-free detection of bioparticles with higher throughput and sensitivity.

Main Methods:

• Development and application of a plasmonic metasurface composed of sub-diffraction plasmonic meta-atom arrays.
• Utilizing MAD-iSCAT to generate bright radiation modes for amplified nanoparticle scattering.
• Employing a dark collective mode in the metasurface to minimize background signal in the absence of nanoparticles.

Main Results:

• Experimental demonstration of significantly enhanced contrast and signal-to-noise ratio for detecting dielectric nanoparticles, exosomes, and proteins.
• Theoretical analysis validating the amplified interferometric imaging capabilities of designed metasurfaces.
• Achieved substantial amplification of detection sensitivity through the use of plasmonic metasurfaces.

Conclusions:

• MAD-iSCAT offers a powerful new tool for label-free detection of nanometer-scale bioparticles.
• The developed technique shows broad applicability in biosensing and optical mass spectrometry.
• MAD-iSCAT enables significantly improved sensitivity and throughput for biological imaging and analysis.