TOMO-POL: Polarization optical diffraction tomography for high-throughput label free lipid droplets morphological analysis in living cells.

Project description:

Understanding biological processes largely begins with the ability to observe them. It is the development of imaging techniques that has enabled modern biology and medicine to study cells and tissues with ever-increasing precision, often without interfering with their natural function. Optical microscopy, despite its long history, remains a rapidly evolving field, offering methods that allow researchers to look deep inside cells and extract far more information from images than was previously possible. One of the most widely used tools is fluorescence microscopy, which relies on glowing markers to selectively visualize specific cellular structures. Although it has played a pivotal role in advancing cell biology, it requires additional sample preparation, may affect cell viability, and rarely enables truly quantitative measurements. For these reasons, growing attention is being directed toward label-free methods, such as quantitative phase and polarization microscopy, which allow gentle, non-invasive investigation of living cells based on their interaction with light.

The aim of this project is to develop a new, advanced multimodal imaging system that integrates complementary optical techniques into a single, coherent platform. At its core lies the development of polarization optical diffraction tomography, a method that enables three-dimensional imaging of cells alongside quantitative measurements of their optical properties, including the refractive index and polarization changes of light passing through the sample. This approach not only allows precise reconstruction of the shape and spatial organization of intracellular structures, but also provides insight into their composition and degree of structural order—information that remains inaccessible to conventional imaging techniques. The project focuses on lipid droplets, small structures present in nearly every cell, which serve as lipid storage compartments and play a key role in energy metabolism, membrane formation, and hormone synthesis. An increasing body of evidence links disruptions in lipid droplet function to metabolic and cardiovascular diseases.

Particular attention will be given to lipid droplets containing cholesterol esters, which, under certain conditions, can adopt an ordered, liquid-crystalline structure. The biological significance of this phenomenon remains poorly understood, including whether it is associated with normal physiological processes, cellular stress responses, or pathological states. Addressing these questions requires methods capable of quantitative, three-dimensional studies of living cells. For this reason, the developed system will be expanded with a super-resolution fluorescence imaging module based on structured illumination, enabling precise localization of lipid droplets and correlation of quantitative optical data with fluorescence images obtained using molecular markers. The combination of label-free imaging with super-resolution fluorescence creates a unified, multimodal research tool that enables non-invasive and comprehensive analysis of lipid droplets in living cells, bridging the gap between classical optical microscopy and costly, technically demanding electron-based methods.