▲(from the left) Professor Chan-Gi Pack and Professor Jun Ki Kim

A research team, led by Professor Chan-Gi Pack and Professor Jun Ki Kim from the Department of Convergence Medicine at Asan Medical Center, recently published their findings. They utilized label-free optical diffraction tomography (ODT) to analyze changes in cellular organelles following invasive manipulation outside the cell.

ODT technology involves projecting light into the cell, collecting scattered light, and reconstructing a three-dimensional (3D) hologram using standard light sources. This technology facilitates accurate quantitative analysis of various physical properties of cell organelles, including refractive index and volume, aiding in the understanding of the relationship between the cell's microenvironment and intracellular biological characteristics.

▲3D image of HeLa cell organelles featured on the cover of ‘Analytical Chemistry’

The research team employed ODT technology to investigate how various cell pretreatment processes, such as chemical cell fixation, temperature changes, and fluorescent staining, influence the physical and chemical properties of HeLa cells. The results demonstrated that essential cell qualities can be compromised during pretreatment. Cell fixation or temperature increase led to an overall decrease in the refractive index values of cell organelles. Notably, unlike the cell nuclei, a significant loss was confirmed in internal cell components such as cytoplasm and organelles. Additionally, it was shown that cell fixation for fluorescent staining and the expression of a specific green fluorescent protein (GFP) gene changed cell density, whereas the GFP gene significantly increased the refractive index of cell organelles compared to chemical fluorescent staining.

This study received funding from the Healthcare Technology R&D Project of the Ministry of Health and Welfare, the Ministry of Science and ICT, and the Ministry of Education. The research findings were published in the latest issue of 'Analytical Chemistry,' a prestigious academic journal in analytical chemistry. The cover of the journal featured a 3D image of HeLa cell organelles used in the research.