Sensing biological and chemical environments
Detecting chemical composition and enzyme activity within lipid membranes
Can the orientations of fluorescent probes be used to sense and image the surrounding chemical environment?
Using points accumulation for imaging in nanoscale topography (PAINT), our engineered Tri-spot PSF, and our Robust Statistical Estimation (RoSE) algorithm capable of measuring molecular orientations, we have characterized how the orientations of Nile red, merocyanine, DiI, and other lipid probes interact with lipid membranes. SMOLM resolves cholesterol concentration, lipid-ordered and liquid-disordered domains, and enzyme activity that cannot be resolved by localization alone.
Read:
- Using light's properties to indirectly see inside a cell membrane - The Source
- Close to the Edge - The Analytical Scientist
- J. Lu, H. Mazidi, T. Ding, O. Zhang, and M. D. Lew, “Single-Molecule 3D Orientation Imaging Reveals Nanoscale Compositional Heterogeneity in Lipid Membranes,” Angew. Chem. Int. Ed. 59, 17572 (2020). [Journal cover, The Source - Washington University, The Analytical Scientist, EurekAlert!, Open Scholarship, Article, Data]
Imaging the nanoscale organization of amyloid aggregates
How can we visualize how amyloid aggregates are organized at the nanoscale?
Using Transient Amyloid Binding (TAB), a polarization-sensitive fluorescence microscope, and our Robust Statistical Estimation (RoSE) algorithm capable of measuring molecular orientation, we have demonstrated SMOLM for resolving the positions and orientations of Nile red (NR) molecules on the surfaces of amyloid aggregates. SMOLM resolves disordered NR orientations that may represent heterogeneous beta-sheet assemblies in amyloid fibrils that cannot be resolved by localization alone.
Read:
- New Microscopy Method Provides Unprecedented Look at Amyloid Protein Structure - OSA news release
- Mechanism Aids Microscopic Study of Fibrils - Photonics Media
- T. Ding*, T. Wu*, H. Mazidi, O. Zhang, and M. D. Lew, “Single-molecule orientation localization microscopy for resolving structural heterogeneities between amyloid fibrils,” Optica 7, 602 (2020). [OSA news release, The Source - Washington University, Article, Data, Summary PDF]
Transient Amyloid Binding (TAB)
How can we visualize amyloid aggregation at nanometer resolution with minimum perturbation over extended time periods?
Amyloid aggregates are signatures of neurodegenerative disorders such as Alzheimer’s disease. We developed Transient Amyloid Binding (TAB) super-resolution microscopy to resolve amyloid structures using the standard probe, Thioflavin T (ThT), without the need for covalent modification or immunostaining of amyloids. Spontaneous binding and corresponding bursts of ThT fluorescence on amyloids are used to reconstruct super-resolution images of native amyloid structures.
Read:
- ‘Blink’ and you won′t miss amyloids - The Source
- Dye gets amyloids to ‘blink’ to make them easier to spot - Futurity
- Technique Uses Well-Known Dye to Watch Amyloid Plaques in the Brain - OSA News Release
- K. Spehar*, T. Ding*, Y. Sun, N. Kedia, J. Lu, G. R. Nahass, M. D. Lew, and J. Bieschke, “Super-Resolution Imaging of Amyloid Structures over Extended Times Using Transient Binding of Single Thioflavin T Molecules,” ChemBioChem 19, 1944 (2018). [Journal cover, The Source - Washington University, NSF Science360, Futurity, EurekAlert!, OSA News Release, Open Scholarship, Article, Summary PDF]