Adaptive dark-field interferometric scattering microscopy for label-free imaging of nanoscale systems

Abstract

Interferometric scattering microscopy (iSCAT) enables label-free detection of nanoscale entities by interfering weak scattered light with a reference field, yielding high sensitivity for single-particle mass photometry, three-dimensional tracking, and kinetic studies of proteins, viruses, and nanoparticles—dynamics elusive to traditional optics. Nonetheless, its efficacy hinges on rigorous background suppression, coherence management, and calibration. We advance dark-field iSCAT (DF iSCAT), merging interferometric precision with dark-field illumination to augment contrast, attenuate coherent artifacts, and enhance detection of ultraweak scatterers. This facilitates non-perturbative visualization of diminutive biomolecules and synthetic nanostructures, sans photobleaching. DF iSCAT emerges as a scalable, high-fidelity modality for nanoscale imaging, with profound implications in structural biology, nanomedicine, proteomics, and materials characterization.