Daniel J. Müller

Last Name

Müller

First Name

Daniel J.

ORCID

0000-0003-3075-0665

Organisational unit

03870 - Müller, Daniel J. / Müller, Daniel J.

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Publications 1 - 10 of 176

High-resolution imaging of 2D outer membrane protein F crystals by atomic force microscopy
Fotiadis, Dimitrios; Müller, Daniel J. (2013)
Methods in Molecular Biology ~ Electron Cystallography of Soluble and Membrane Proteins
In this chapter the methodological bases are provided to achieve subnanometer resolution on two-dimensional (2D) membrane protein crystals by atomic force microscopy (AFM). This is outlined in detail with the example of AFM studies of the outer membrane protein F (OmpF) from the bacterium Escherichia coli (E. coli). We describe in detail the high-resolution imaging of 2D OmpF crystals in aqueous solution and under near-physiological conditions. The topographs of OmpF, and stylus effects and artifacts encountered when imaging by AFM are discussed.
Virus stamping for targeted single-cell infection in vitro and in vivo
Schubert, Rajib; Trenholm, Stuart; Balint, Kamill; et al. (2018)
Nature Biotechnology
Mechanical stimulation and electrophysiological monitoring at subcellular resolution reveals differential mechanosensation of neurons within networks
Kasuba, Krishna Chaitanya; Buccino, Alessio Paolo; Bartram, Julian; et al. (2024)
Nature Nanotechnology
A growing consensus that the brain is a mechanosensitive organ is driving the need for tools that mechanically stimulate and simultaneously record the electrophysiological response of neurons within neuronal networks. Here we introduce a synchronized combination of atomic force microscopy, high-density microelectrode array and fluorescence microscopy to monitor neuronal networks and to mechanically characterize and stimulate individual neurons at piconewton force sensitivity and nanometre precision while monitoring their electrophysiological activity at subcellular spatial and millisecond temporal resolution. No correlation is found between mechanical stiffness and electrophysiological activity of neuronal compartments. Furthermore, spontaneously active neurons show exceptional functional resilience to static mechanical compression of their soma. However, application of fast transient (∼500 ms) mechanical stimuli to the neuronal soma can evoke action potentials, which depend on the anchoring of neuronal membrane and actin cytoskeleton. Neurons show higher responsivity, including bursts of action potentials, to slower transient mechanical stimuli (∼60 s). Moreover, transient and repetitive application of the same compression modulates the neuronal firing rate. Seemingly, neuronal networks can differentiate and respond to specific characteristics of mechanical stimulation. Ultimately, the developed multiparametric tool opens the door to explore manifold nanomechanobiological responses of neuronal systems and new ways of mechanical control.
A practical guide to quantify cell adhesion using single-cell force spectroscopy
Friedrichs, Jens; Legate, Kyle R.; Schubert, Rajib; et al. (2013)
Methods
Integrin identity shapes the transcriptome and mechanical stability of mammalian fibroblasts
Sharma, Upnishad; Nava, Michele; Okoniewski, Michal; et al. (2025)
Molecular Biology of the Cell ~ CELL BIO 2024 Abstracts: Poster Presentations
Detecting Ligand-Binding Events and Free Energy Landscape while Imaging Membrane Receptors at Subnanometer Resolution
Pfreundschuh, Moritz; Harder, Daniel; Ucurum, Zöhre; et al. (2017)
Nano Letters
Identifying and quantifying two ligand-binding sites while imaging native human membrane receptors by AFM
Pfreundschuh, Moritz; Alsteens, David; Wieneke, Ralph; et al. (2015)
Nature Communications
A current challenge in life sciences is to image cell membrane receptors while characterizing their specific interactions with various ligands. Addressing this issue has been hampered by the lack of suitable nanoscopic methods. Here we address this challenge and introduce multifunctional high-resolution atomic force microscopy (AFM) to image human protease-activated receptors (PAR1) in the functionally important lipid membrane and to simultaneously localize and quantify their binding to two different ligands. Therefore, we introduce the surface chemistry to bifunctionalize AFM tips with the native receptor-activating peptide and a tris-N-nitrilotriacetic acid (tris-NTA) group binding to a His10-tag engineered to PAR1. We further introduce ways to discern between the binding of both ligands to different receptor sites while imaging native PAR1s. Surface chemistry and nanoscopic method are applicable to a range of biological systems in vitro and in vivo and to concurrently detect and localize multiple ligand-binding sites at single receptor resolution.
Rheology of rounded mammalian cells over continuous high-frequencies
Fläschner, Gotthold Viktor; Roman, Cosmin I.; Strohmeyer, Nico; et al. (2021)
Nature Communications
Understanding the viscoelastic properties of living cells and their relation to cell state and morphology remains challenging. Low-frequency mechanical perturbations have contributed considerably to the understanding, yet higher frequencies promise to elucidate the link between cellular and molecular properties, such as polymer relaxation and monomer reaction kinetics. Here, we introduce an assay, that uses an actuated microcantilever to confine a single, rounded cell on a second microcantilever, which measures the cell mechanical response across a continuous frequency range ≈ 1–40 kHz. Cell mass measurements and optical microscopy are co-implemented. The fast, high-frequency measurements are applied to rheologically monitor cellular stiffening. We find that the rheology of rounded HeLa cells obeys a cytoskeleton-dependent power-law, similar to spread cells. Cell size and viscoelasticity are uncorrelated, which contrasts an assumption based on the Laplace law. Together with the presented theory of mechanical de-embedding, our assay is generally applicable to other rheological experiments.
Quantification of surface tension and internal pressure generated by single mitotic cells
Fischer-Friedrich, Elisabeth; Hyman, Anthony A.; Jülicher, Frank; et al. (2014)
Scientific Reports
During mitosis, adherent cells round up, by increasing the tension of the contractile actomyosin cortex while increasing the internal hydrostatic pressure. In the simple scenario of a liquid cell interior, the surface tension is related to the local curvature and the hydrostatic pressure difference by Laplace's law. However, verification of this scenario for cells requires accurate measurements of cell shape. Here, we use wedged micro-cantilevers to uniaxially confine single cells and determine confinement forces while concurrently determining cell shape using confocal microscopy. We fit experimentally measured confined cell shapes to shapes obeying Laplace's law with uniform surface tension and find quantitative agreement. Geometrical parameters derived from fitting the cell shape, and the measured force were used to calculate hydrostatic pressure excess and surface tension of cells. We find that HeLa cells increase their internal hydrostatic pressure excess and surface tension from ≈ 40 Pa and 0.2 mNm−1 during interphase to ≈ 400 Pa and 1.6 mNm−1 during metaphase. The method introduced provides a means to determine internal pressure excess and surface tension of rounded cells accurately and with minimal cellular perturbation, and should be applicable to characterize the mechanical properties of various cellular systems.
Atomic Force Microscopy to Study Mechanics of Living Mitotic Mammalian Cells
Toyoda, Yusuke; Stewart, Martin P.; Hyman, Anthony A.; et al. (2011)
Japanese Journal of Applied Physics

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Daniel J. Müller

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