I investigate viral membranes and host interactions with high spatiotemporal resolution optical microscopy. Advanced optical microscopy methods have the advantage of live imaging capability in combination with molecular specific labeling. My aim is to further our understanding of virus infection mechanisms and how cellular processes are exploited specifically by viruses.
iSCAT microscopy and particle tracking with tailored spatial coherence
Mahdi Mazaheri, Kiarash Kasaian, David Albrecht, Jan Renger, Tobias Utikal, Cornelia Holler, Vahid Sandoghdar
Interferometric scattering (iSCAT) microscopy has demonstrated unparalleled performance among label-free optical methods for detecting and imaging isolated nanoparticles and molecules. However, when imaging complex structures such as biological cells, the superposition of the scattering fields from different locations of the sample leads to a speckle-like background, posing a significant challenge in deciphering fine features. Here, we show that by controlling the spatial coherence of the illumination, one can eliminate the spurious speckle without sacrificing sensitivity. We demonstrate this approach by positioning a rotating diffuser coupled with an adjustable lens and an iris in the illumination path. We report on imaging at a high frame rate of 25 kHz and across a large field of view of 100µm×100µm, while maintaining diffraction-limited resolution. We showcase the advantages of these features by three-dimensional (3D) tracking over 1000 vesicles in a single COS-7 cell and by imaging the dynamics of the endoplasmic reticulum (ER) network. Our approach opens the door to the combination of label-free imaging, sensitive detection, and 3D high-speed tracking using wide-field iSCAT microscopy.
Measuring Concentration of Nanoparticles in Polydisperse Mixtures Using Interferometric Nanoparticle Tracking Analysis
Anna D. Kashkanova, David Albrecht, Michelle Küppers, Martin Blessing, Vahid Sandoghdar
Quantitative measurements of nanoparticle concentration in liquid suspensions are in high demand, for example, in the medical and food industries. Conventional methods remain unsatisfactory, especially for polydisperse samples with overlapping size ranges. Recently, we introduced interferometric nanoparticle tracking analysis (iNTA) for high-precision measurement of nanoparticle size and refractive index. Here, we show that by counting the number of trajectories that cross the focal plane, iNTA can measure concentrations of subpopulations in a polydisperse mixture in a quantitative manner and without the need for a calibration sample. We evaluate our method on both monodisperse samples and mixtures of known concentrations. Furthermore, we assess the concentration of SARS-CoV-2 in supernatant samples obtained from infected cells.
Confocal Interferometric Scattering Microscopy Reveals 3D Nanoscopic Structure and Dynamics in Live Cells
Michelle Küppers, David Albrecht, Anna D. Kashkanova, Jennifer Lühr, Vahid Sandoghdar
Nature Communications
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1962 (2023)
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Bright-field light microscopy and related techniques continue to play a key role in life sciences because they provide a facile and label-free insight into biological specimen. However, lack of three-dimensional imaging and low sensitivity to nanoscopic features hamper their application in high-end quantitative studies. Here, we remedy these shortcomings by employing confocal interferometric scattering (iSCAT) microscopy. We demonstrate the performance of this label-free technique in a selection of case studies in live cells and benchmark our findings against simultaneously acquired fluorescence images. We reveal the nanometric topography of the nuclear envelope, quantify the dynamics of the endoplasmic reticulum, detect single microtubules, and map nanoscopic diffusion of clathrin-coated pits undergoing endocytosis. Furthermore, we introduce the combination of confocal and wide-field iSCAT modalities for simultaneous imaging of cellular structures and high-speed tracking of nanoscopic entities such as single SARS-CoV2 virions. Confocal iSCAT can be readily implemented as an additional contrast mechanism in existing laser scanning microscopes.
The vaccinia virus chondroitin sulfate binding protein drives host membrane curvature to facilitate fusion L. Pokorny, J. J. Burden, D. Albrecht, R. Bamford, K. E. Leigh, P. Sridhar, T. J. Knowles, Y. Modis and J. Mercer bioRxiv preprint. doi: 10.1101/2022.03.10.483741 (2022)
Poxviruses package viral redox proteins in lateral bodies and modulate the host oxidative response S. R. Bidgood, K. Novy, A. Collopy, D. Albrecht, M. Krause, J. J. Burden, B. Wollscheid and J. Mercer PLoS Pathogens. doi: 10.1371/journal.ppat.1010614 (2022)
Modulation of Early Host Innate Immune Response by an Avipox Vaccine Virus’ Lateral Body Protein E. S. Giotis, S. M. Laidlaw, S. R. Bidgood, D. Albrecht, J. J. Burden, R. C. Robey, J. Mercer and M. a. Skinner Biomedicines. doi: 10.3390/biomedicines8120634 (2020)
Modulation of Early Host Innate Immune Response by an Avipox Vaccine Virus’ Lateral Body Protein E. S. Giotis, S. M. Laidlaw, S. R. Bidgood, D. Albrecht, J. J. Burden, R. C. Robey, J. Mercer and M. a. Skinner Biomedicines. doi: 10.3390/biomedicines8120634 (2020)
Spectrally red-shifted fluorescent fiducial markers for optimal drift correction in localization microscopy Balinovic, D. Albrecht and U. Endesfelder Journal of Physics D: Applied Physics. doi: 10.1088/1361-6463/ab0862 (2019)
Nanoscale polarization of the entry fusion complex of vaccinia virus drives efficient fusion R. D. M. Gray, D. Albrecht, C. Beerli, M. Huttunen, G. H. Cohen, I. J. White, J. J. Burden, R. Henriques and J. Mercer Nature Microbiology. doi: 10.1038/s41564-019-0488-4 (2019)
Fix your membrane receptor imaging: Actin cytoskeleton and CD4 membrane organization disruption by chemical fixation P. M. Pereira, D. Albrecht, S. Culley, C. Jacobs, M. Marsh, J. Mercer and R. Henriques Frontiers in Immunology. doi: 10.3389/fimmu.2019.00675
Quantitative mapping and minimization of super-resolution optical imaging artifacts S. Culley, D. Albrecht, C. Jacobs, P. M. Pereira, C. Leterrier, J. Mercer and R. Henriques Nature Methods. doi: 10.1038/nmeth.4605 (2018)
Revealing Compartmentalized Diffusion in Living Cells with Interferometric Scattering Microscopy G. de Wit, D. Albrecht, H. Ewers and P. Kukura Biophysical Journal. doi: 10.1016/j.bpj.2018.05.007
Nanoscopic compartmentalization of membrane protein motion at the axon initial segment D. Albrecht, C. M. Winterflood, M. Sadeghi, T. Tschager, F. Noé and H. Ewers The Journal of Cell Biology. doi: 10.1083/jcb.201603108 (2016)
Regulated endosomal trafficking of Diacylglycerol lipase alpha (DAGLα) generates distinct cellular pools; implications for endocannabinoid signaling Y. Zhou, F. V. Howell, O. O. Glebov, D. Albrecht, G. Williams and P. Doherty Molecular and Cellular Neuroscience. doi: 10.1016/j.mcn.2016.08.011 (2016)
Dual color single particle tracking via nanobodies D. Albrecht, C. M. Winterflood and H. Ewers Methods and Applications in Fluorescence. doi: 10.1088/2050-6120/3/2/024001 (2015)
Single-molecule microscopy of molecules tagged with GFP or RFP derivatives in mammalian cells using nanobody binders E. Platonova, C. M. Winterflood, A. Junemann, D. Albrecht, J. Faix and H. Ewers Methods. doi: 10.1016/j.ymeth.2015.06.018 (2015)
Tetraspanin-3 is an organizer of the multi-subunit Nogo-A signaling complex N. K. Thiede-Stan, B. Tews, D. Albrecht, Z. Ristic, H. Ewers and M. E. Schwab Journal of Cell Science. doi: 10.1242/jcs.167981 (2015)
Dual-Color 3D Superresolution Microscopy by Combined Spectral-Demixing and Biplane Imaging M. Winterflood, E. Platonova, D. Albrecht and H. Ewers Biophysical Journal. doi: 10.1016/j.bpj.2015.05.026 (2015)
Spatial segregation of polarity factors into distinct cortical clusters is required for cell polarity control J. Dodgson, A. Chessel, M. Yamamoto, F. Vaggi, S. Cox, E. Rosten, D. Albrecht, M. Geymonat, A. Csikasz-Nagy, M. Sato and R. E. Carazo-Salas Nature Communications. doi: 10.1038/ncomms2813 (2013)
Small delay, big waves: a minimal delayed negative feedback model captures Escherichia coli single cell SOS kinetics L. Hilbert, D. Albrecht and M. C. Mackey Mol. BioSyst. doi: 10.1039/c1mb05122a (2011)
David Albrecht studied biochemistry at Hanover University (BSc) and ETH Zurich (MSc) as an undergraduate student. He continued at ETH Zurich for his PhD thesis on 'The axon initial segment diffusion barrier at the nanoscopic level' in the group of Dr Helge Ewers. In 2016 he joined Dr Jason Mercer and Dr Ricardo Henriques at University College London as a postdoc to work on virus-host interactions, funded by a Marie Sklodowska-Curie fellowship. David joined the group of Dr Vahid Sandoghdar at the Max Planck Institute for the Science of Light (MPL) in Erlangen in 2019 as a postdoc to continue working with viruses.
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