title: Stain-free quantification of chromosomes in live cells using regularized tomographic phase microscopy.
abstract: Refractive index imaging is a label-free technique that enables long-term monitoring of the internal structures and molecular composition in living cells with minimal perturbation. Existing tomographic methods for the refractive index imaging lack 3-D resolution and result in artifacts that prevent accurate refractive index quantification. To overcome these limitations without compromising the capability to observe a sample in its most native condition, we have developed a regularized tomographic phase microscope (RTPM) enabling accurate refractive index imaging of organelles inside intact cells. With the enhanced accuracy, we quantify the mass of chromosomes in intact living cells, and differentiate two human colon cancer lines, HT-29 and T84 cells, solely based on the non-aqueous (dry) mass of chromosomes. In addition, we demonstrate chromosomal imaging using a dual-wavelength RTPM, which shows its potential to determine the molecular composition of cellular organelles in live cells.
authors.affiliation: G. R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America. ysung@mit.edu
authors.forename: Yongjin
authors.initials: Y
authors.lastname: Sung
authors.forename: Wonshik
authors.initials: W
authors.lastname: Choi
authors.forename: Niyom
authors.initials: N
authors.lastname: Lue
authors.forename: Ramachandra R
authors.initials: RR
authors.lastname: Dasari
authors.forename: Zahid
authors.initials: Z
authors.lastname: Yaqoob
mesh_terms: D045744:Cell Line, Tumor; D002875:Chromosomes; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008858:Microscopy, Phase-Contrast / Q000379:methods*; D012031:Refractometry; D015203:Reproducibility of Results; D041622:Tomography, Optical / Q000379:methods*