Direct visualization and characterization of nanosized biological particles such as
viruses, vesicles and protein aggregates are important for various applications in
medicine. Specifically, exosomes (30-150 nm in diameter) gained huge interest due
to their potential role as a biomarker in cancer diagnosis and prognosis, however
direct detection of these particles is challenging due to their small size. Interferometric
microscopy allows detection of these particles without using any labels. We show that
visibility of nanoparticles can be enhanced in interferometric microscopy by utilizing
defocused images. In this paper, with the proposed method Depth Scanning Correlation,
we demonstrate label-free detection of individual exosomes isolated from breast cancer
cell culture isolated by using Exosome Total Isolation Chip (ExoTIC). Proposed imaging
system combined with an isolation tool, can be used in a wide range of applications,
where label-free detection of single biological nanoparticles is needed.
