Coherent fluctuation imaging for studying cellular organization

• Applicant: Professor Dr. Jörg Enderlein
• Subject Area: Biophysics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 565717292

In this collaborative project between Academia Sinica (Taiwan) and Georg August University Göttingen (Germany), we propose a novel optical microscopy approach that integrates concepts from Super-resolution Optical Fluctuation Imaging (SOFI) and Image Correlation Spectroscopy (ICS) with iSCAT microscopy to enhance spatial resolution and extract quantitative dynamic information from nanoscale biological systems. SOFI, a computational fluorescence microscopy method, improves resolution by analyzing temporal fluorescence fluctuations and extracting high-order statistical correlations. ICS, a fluorescence-based analytical technique, quantifies molecular organization, diffusion, and interactions by statistically analyzing fluorescence intensity fluctuations. While both SOFI and ICS have been widely used in fluorescence imaging, their application to iSCAT remains unexplored. By extending these principles to the coherent iSCAT signals, we aim to overcome current resolution barriers and provide a new analytical framework for studying biomolecular dynamics in a label-free manner. We aim to apply our new methods for studying chromatin dynamics in the cell nucleus. The core research objectives of the project are 1. Develop a Theoretical Model for Coherent Imaging: Using the Richards-Wolf imaging theory, the project will model the imaging of large distributions of scattering particles while accounting for coherent interactions. 2. Enhance Super-Resolution Coherent Fluctuation Imaging: SOFI will be applied to iSCAT images to improve resolution and contrast, extending its applicability beyond fluorescence microscopy. 3. Extract Molecular Dynamics Data: ICS techniques will be applied to iSCAT to quantify diffusivity, correlated motion, density, and other biophysical parameters. 4. Investigate Higher-Order Correlation Analysis: The extended time scales in iSCAT imaging will allow for computing third-order ICS correlations, enabling studies of vorticity and spatially correlated diffusion. 5. Validate with Simulations and Experiments: Theoretical models will be validated using Brownian dynamics simulations and experimental iSCAT imaging of nanoparticles. 6. Explore Chromatin Organization and Dynamics: iSCAT-based SOFI/ICS analysis will be used to study chromatin dynamics in live mammalian cell nuclei. We will explore correlations between chromatin organization, subdiffusion behaviors, and density.

• DFG Programme: Research Grants
• International Connection: Taiwan
• Partner Organisation: National Science and Technology Council (NSTC)
• Cooperation Partner: Professor Dr. Chia-Lung Hsieh