Zellen sind die grundlegenden Einheiten biologischer Systeme. Sie haben besondere physikalische Eigenschaften, die es ihnen ermöglichen, sich in ihrer physikalischen 3D-Umgebung zu bewegen und ihre biologischen Funktionen zu erfüllen. Wir untersuchen diese physikalischen - mechanischen und optischen - Eigenschaften von lebenden Zellen und Geweben mit Hilfe neuartiger photonischer und biophysikalischer Werkzeuge, um ihre biologische Bedeutung zu testen. Unser Ziel ist der Transfer unserer Erkenntnisse in die medizinische Anwendung auf den Gebieten der verbesserten Diagnose von Krankheiten und neuer Ansätze in der regenerativen Medizin.
Objektiv messbare Parallelen zwischen Long COVID und ME/CFS: Bayerns Gesundheitsminister Klaus Holetschek und Ausschussvorsitzender Bernhard Seidenath…
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Cells actively sense and respond to a variety of mechanical signals — a process known as mechanosensing. Mechanical cues provided by the extracellular environment can modulate a wide spectrum of cellular events, including cell proliferation, differentiation and protein production. Read More...
Cells define and largely form their surrounding tissues and, in return, receive biochemical and physical cues from them. We are working on resolving this interdependence by quantifying these tissue mechanical properties, correlating them with biological function, investigating their origin and ultimately controlling them. Read More...
Quantitative phase imaging through an ultra-thin lensless fiber endoscope
Jiawei Sun, Jiachen Wu, Ruchi Goswami, Salvatore Girardo, Liangcai Cao, Jochen Guck, Nektarios Koukourakis, Jürgen W. Czarske
Quantitative phase imaging (QPI) is a label-free technique providing both morphology and quantitative biophysical information in biomedicine. However, applying such a powerful technique to in vivo pathological diagnosis remains challenging. Multi-core fiber bundles (MCFs) enable ultra-thin probes for in vivo imaging, but current MCF imaging techniques are limited to amplitude imaging modalities. We demonstrate a computational lensless microendoscope that uses an ultra-thin bare MCF to perform quantitative phase imaging with microscale lateral resolution and nanoscale axial sensitivity of the optical path length. The incident complex light field at the measurement side is precisely reconstructed from the far-field speckle pattern at the detection side, enabling digital refocusing in a multi-layer sample without any mechanical movement. The accuracy of the quantitative phase reconstruction is validated by imaging the phase target and hydrogel beads through the MCF. With the proposed imaging modality, three-dimensional imaging of human cancer cells is achieved through the ultra-thin fiber endoscope, promising widespread clinical applications.
PNIPAAm microgels with defined network architecture as temperature sensors in optical stretchers
Nicolas Hauck, Timon Beck, Gheorghe Cojoc, Raimund Schlüßler, Saeed Ahmed, Ivan Raguzin, Martin Mayer, Jonas Schubert, Paul Müller, et al.
Stretching individual living cells with light is a standard method to assess their mechanical properties. Yet, heat introduced by the laser light of optical stretchers may unwittingly change the mechanical properties of cells therein. To estimate the temperature induced by an optical trap, we introduce cell-sized, elastic poly(N-isopropylacrylamide) (PNIPAAm) microgels that relate temperature changes to hydrogel swelling. For their usage as a standardized calibration tool, we analyze the effect of free-radical chain-growth gelation (FCG) and polymer-analogous photogelation (PAG) on hydrogel network heterogeneity, micromechanics, and temperature response by Brillouin microscopy and optical diffraction tomography. Using a combination of tailor-made PNIPAAm macromers, PAG, and microfluidic processing, we obtain microgels with homogeneous network architecture. With that, we expand the capability of standardized microgels in calibrating and validating cell mechanics analysis, not only considering cell and microgel elasticity but also providing stimuli-responsiveness to consider dynamic changes that cells may undergo during characterization.
Long COVID: Association of Functional Autoantibodies against G-Protein-Coupled Receptors with an Impaired Retinal Microcirculation
Charlotte Szewczykowski, Christian Mardin, Marianna Lucio, Gerd Wallukat, Jakob Hoffmanns, Thora Schröder, Franziska Raith, Lennart Rogge, Felix Heltmann, et al.
Long COVID (LC) describes the clinical phenotype of symptoms after infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Diagnostic and therapeutic options are limited, as the pathomechanism of LC is elusive. As the number of acute SARS-CoV-2 infections was and is large, LC will be a challenge for the healthcare system. Previous studies revealed an impaired blood flow, the formation of microclots, and autoimmune mechanisms as potential factors in this complex interplay. Since functionally active autoantibodies against G-protein-coupled receptors (GPCR-AAbs) were observed in patients after SARS-CoV-2 infection, this study aimed to correlate the appearance of GPCR-AAbs with capillary microcirculation. The seropositivity of GPCR-AAbs was measured by an established cardiomyocyte bioassay in 42 patients with LC and 6 controls. Retinal microcirculation was measured by OCT–angiography and quantified as macula and peripapillary vessel density (VD) by the Erlangen-Angio Tool. A statistical analysis yielded impaired VD in patients with LC compared to the controls, which was accentuated in female persons. A significant decrease in macula and peripapillary VD for AAbs targeting adrenergic β2-receptor, MAS-receptor angiotensin-II-type-1 receptor, and adrenergic α1-receptor were observed. The present study might suggest that a seropositivity of GPCR-AAbs can be linked to an impaired retinal capillary microcirculation, potentially mirroring the systemic microcirculation with consecutive clinical symptoms.
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Max-Planck-Institut für die Physik des Lichts
Das Max-Planck-Institut hat seinen Sitz direkt am Südgelände der Friedrich-Alexander-Universität Erlangen-Nürnberg, auf dem die Technische Fakultät angesiedelt ist. Informationen zur Anfahrt finden Sie hier.
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