Characterizing Organelles in Live Stem Cells Using Label-Free Optical Diffraction Tomography

The cell nucleus is a three-dimensional, dynamic organelle organized into subnuclear compartments such as chromatin and nucleoli. The structure and function of these compartments are maintained by diffusion and interactions between related factors as well as by dynamic and structural changes. Recent studies using fluorescent microscopic techniques suggest that protein factors can access and are freely mobile in heterochromatin and in mitotic chromosomes, despite their densely packed structure. However, the physicochemical properties of the chromosome during cell division are not fully understood. In the present study, characteristic properties such as the refractive index (RI), volume of the mitotic chromosomes, and diffusion coefficient (D) of fluorescent probes inside the chromosome were quantified using an approach combining label-free optical diffraction tomography with complementary confocal laser-scanning microscopy and fluorescence correlation spectroscopy. Variations in these parameters correlated with osmotic conditions, suggesting that changes in RI are consistent with those of the diffusion coefficient for mitotic chromosomes and cytosol. Serial RI tomography images of chromosomes in live cells during mitosis were compared with three-dimensional confocal micrographs to demonstrate that compaction and decompaction of chromosomes induced by osmotic change were characterized by linked changes in chromosome RI, volume, and the mobilities of fluorescent proteins.

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Label-free analysis and identification of white blood cell population using optical diffraction tomography

Asia Communications and Photonics Conference 2015 ◽

10.1364/acpc.2015.asu2a.159 ◽

2015 ◽

Author(s):

Jonghee Yoon ◽

Kyoohyun Kim ◽

Min-hyeok Kim ◽

YoungJu Jo ◽

Suk-Jo Kang ◽

...

Keyword(s):

Blood Cell ◽

Cell Population ◽

White Blood Cell ◽

Optical Diffraction ◽

Diffraction Tomography ◽

Label Free ◽

Optical Diffraction Tomography

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Label-free monitoring of 3D cortical neuronal growth in vitro using optical diffraction tomography

10.1101/2021.07.31.454602 ◽

2021 ◽

Author(s):

Ariel J. Lee ◽

DongJo Yoon ◽

SeungYun Han ◽

Herve Hugonnet ◽

WeiSun Park ◽

...

Keyword(s):

Optical Diffraction ◽

Neuronal Cultures ◽

Multiple Time ◽

Diffraction Tomography ◽

Label Free ◽

Neuronal Growth ◽

Monitoring Method ◽

Optical Diffraction Tomography ◽

Immunofluorescence Labeling

The highly complex central nervous systems of mammals are often studied using three-dimensional (3D) in vitro primary neuronal cultures. A coupled confocal microscopy and immunofluorescence labeling are widely utilized for visualizing the 3D structures of neurons. However, this requires fixation of the neurons and is not suitable for monitoring an identical sample at multiple time points. Thus, we propose a label-free monitoring method for 3D neuronal growth based on refractive index tomograms obtained by optical diffraction tomography. The 3D morphology of the neurons was clearly visualized, and the developmental processes of neurite outgrowth in 3D spaces were analyzed for individual neurons.

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Three-dimensional label-free observation of individual bacteria upon antibiotic treatment using optical diffraction tomography

10.1101/775346 ◽

2019 ◽

Author(s):

Jeonghun Oh ◽

Jea Sung Ryu ◽

Moosung Lee ◽

Jaehwang Jung ◽

Seung yun Han ◽

...

Keyword(s):

Imaging Techniques ◽

Three Dimensional ◽

Time Lapse ◽

Optical Diffraction ◽

Response Analysis ◽

Diffraction Tomography ◽

Label Free ◽

Optical Diffraction Tomography ◽

Quantitative Manner ◽

Basic Studies

AbstractMeasuring alterations in bacteria upon antibiotic application is important for basic studies in microbiology, drug discovery, and clinical diagnosis, and disease treatment. However, imaging and 3D time-lapse response analysis of individual bacteria upon antibiotic application remain largely unexplored mainly due to limitations in imaging techniques. Here, we present a method to systematically investigate the alterations in individual bacteria in 3D and quantitatively analyze the effects of antibiotics. Using optical diffraction tomography, in-situ responses of Escherichia coli and Bacillus subtilis to various concentrations of ampicillin were investigated in a label-free and quantitative manner. The presented method reconstructs the dynamic changes in the 3D refractive-index distributions of living bacteria in response to antibiotics at sub-micrometer spatial resolution.

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