Search

Your search keyword '"Spatz, Joachim P."' showing total 1,171 results
Start Over Author "Spatz, Joachim P."
1,171 results on '"Spatz, Joachim P."'

1. Quantum-Enhanced Diamond Molecular Tension Microscopy for Quantifying Cellular Forces

Author

Xu, Feng, Zhang, Shuxiang, Ma, Linjie, Hou, Yong, Li, Jie, Denisenko, Andrej, Li, Zifu, Spatz, Joachim, Wrachtrup, Jörg, Wei, Qiang, and Chu, Zhiqin

Subjects
Quantitative Biology - Cell Behavior
Abstract

The constant interplay and information exchange between cells and their micro-environment are essential to their survival and ability to execute biological functions. To date, a few leading technologies such as traction force microscopy, have been broadly used in measuring cellular forces. However, the considerable limitations, regarding the sensitivity and ambiguities in data interpretation, are hindering our thorough understanding of mechanobiology. Herein, we propose an innovative approach, namely quantum-enhanced diamond molecular tension microscopy (QDMTM), to precisely quantify the integrin-based cell adhesive forces. Specifically, we construct a force sensing platform by conjugating the magnetic nanotags labeled, force-responsive polymer to the surface of diamond membrane containing nitrogen vacancy (NV) centers. Thus, the coupled mechanical information can be quantified through optical readout of spin relaxation of NV centers modulated by those magnetic nanotags. To validate QDMTM, we have carefully performed corresponding measurements both in control and real cell samples. Particularly, we have obtained the quantitative cellular adhesion force mapping by correlating the measurement with established theoretical model. We anticipate that our method can be routinely used in studying important issues like cell-cell or cell-material interactions and mechanotransduction., Comment: 51 pages, 20 figures

Published
2023

4. Dynamic Actuation of DNA-Assembled Plasmonic Nanostructures in Microfluidic Cell-Sized Compartments

Author

Goepfrich, Kerstin, Urban, Maximilian J., Frey, Christoph, Platzman, Ilia, Spatz, Joachim P., and Liu, Na

Subjects
Physics - Biological Physics, Physics - Optics
Abstract

Molecular motor proteins form the basis of cellular dynamics. Recently, notable efforts have led to the creation of their DNA-based mimics, which can carry out complex nanoscale motion. However, such functional analogues have not yet been integrated or operated inside synthetic cells toward the goal of realizing artificial biological systems entirely from the bottom-up. In this Letter, we encapsulate and actuate DNA-assembled dynamic nanostructures inside cell-sized microfluidic compartments. These encapsulated DNA nanostructures not only exhibit structural reconfigurability owing to their pH-sensitive molecular switches upon external stimuli but also possess optical feedback enabled by the integrated plasmonic probes. In particular, we demonstrate the power of microfluidic compartmentalization for achieving on-chip plasmonic enantiomer separation and substrate filtration. Our work exemplifies that the two unique tools, droplet-based microfluidics and DNA technology, offering high precision on the microscale and nanoscale, respectively, can be brought together to greatly enrich the complexity and diversity of functional synthetic systems.

Published
2021
Full Text
View/download PDF

6. Morphology and Motility of Cells on Soft Substrates

Author

Goychuk, Andriy, Brückner, David B., Holle, Andrew W., Spatz, Joachim P., Broedersz, Chase P., and Frey, Erwin

Subjects
Physics - Biological Physics, Quantitative Biology - Cell Behavior
Abstract

Recent experiments suggest that the interplay between cells and the mechanics of their substrate gives rise to a diversity of morphological and migrational behaviors. Here, we develop a Cellular Potts Model of polarizing cells on a visco-elastic substrate. We compare our model with experiments on endothelial cells plated on polyacrylamide hydrogels to constrain model parameters and test predictions. Our analysis reveals that morphology and migratory behavior are determined by an intricate interplay between cellular polarization and substrate strain gradients generated by traction forces exerted by cells (self-haptotaxis).

Published
2018

13. Investigating the inner structure of focal adhesions with single-molecule localization microscopy

Author

Deschout, Hendrik, Platzman, Ilia, Sage, Daniel, Feletti, Lely, Spatz, Joachim P., and Radenovic, Aleksandra

Subjects
Physics - Biological Physics
Abstract

Cells rely on focal adhesions (FAs) to carry out a variety of important tasks, including motion, environmental sensing, and adhesion to the extracellular matrix. Although attaining a fundamental characterization of FAs is a compelling goal, their extensive complexity and small size, which can be below the diffraction limit, have hindered a full understanding. In this study we have used single-molecule localization microscopy (SMLM) to investigate integrin $\beta$3 and paxillin in rat embryonic fibroblasts growing on two different extracellular matrix-representing substrates (i.e. fibronectin-coated substrates and specifically bio-functionalized nano-patterned substrates). To quantify the substructure of FAs, we developed a method based on expectation maximization of a Gaussian mixture that accounts for localization uncertainty and background. Analysis of our SMLM data indicates that the structures within FAs, characterized as a Gaussian mixture, typically have areas between 0.01 and 1 $\mu$m$^2$, contain 10 to 100 localizations, and can exhibit substantial eccentricity. Our approach based on SMLM opens new avenues for studying structural and functional biology of molecular assemblies that display substantial varieties in size, shape, and density.

Published
2017

14. Modular Porous Polymer-Based Microcapsules for Trapping and Near-Infrared Light-Triggered Killing of Bacteria via Gold Nanorods.

Author

Conzelmann, Nina F., Benimeli Borràs, Ariadna, Muduli, Saradaprasan, Schramm, Anastassiya, Jeschenko, Pascal M., Platzman, Ilia, and Spatz, Joachim P.

Abstract

Due to the increasing occurrence of antibiotic-resistant bacterial strains worldwide, there is an urgent need for developing antibiotic-independent strategies to combat bacterial infections. In this study, we developed a modular approach for trapping, retaining, and killing bacteria by means of porous, poly-(lactic-co-glycolic acid) (PLGA)-based microcapsules with integrated gold nanorods (AuNRs). AuNRs were coated with thiol-functionalized PLGA beforehand to ensure efficient integration into the hydrophobic microcapsule shells. For the efficient generation of AuNR-functionalized microcapsules, we designed and developed a fast and reliable one-pot bulk emulsification production method. When exposing the AuNR-decorated microcapsules to near-infrared light, both motile and nonmotile bacteria were killed in a highly localized manner due to AuNR-generated heat. Importantly, fibroblast cell viability tests performed with AuNR-decorated microcapsules revealed good biocompatibility of the system. Such a modular antibacterial system can be employed in various applications, including, but not limited to, implant coatings, flushing solutions, and sewage treatment. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

19. Stem cell migration and mechanotransduction on linear stiffness gradient hydrogels

Author

Hadden, William J, Young, Jennifer L, Holle, Andrew W, McFetridge, Meg L, Kim, Du Yong, Wijesinghe, Philip, Taylor-Weiner, Hermes, Wen, Jessica H, Lee, Andrew R, Bieback, Karen, Vo, Ba-Ngu, Sampson, David D, Kennedy, Brendan F, Spatz, Joachim P, Engler, Adam J, and Choi, Yu Suk

Subjects
Stem Cell Research, Regenerative Medicine, Bioengineering, Acrylamide, Acrylic Resins, Adult, Cell Adhesion, Cell Culture Techniques, Cell Line, Cell Movement, Elastic Modulus, Humans, Hydrogels, Mechanotransduction, Cellular, Polymerization, Stem Cells, mechanobiology, stem cell migration, stem cell differentiation, extracellular matrix, stiffness
Abstract

The spatial presentation of mechanical information is a key parameter for cell behavior. We have developed a method of polymerization control in which the differential diffusion distance of unreacted cross-linker and monomer into a prepolymerized hydrogel sink results in a tunable stiffness gradient at the cell-matrix interface. This simple, low-cost, robust method was used to produce polyacrylamide hydrogels with stiffness gradients of 0.5, 1.7, 2.9, 4.5, 6.8, and 8.2 kPa/mm, spanning the in vivo physiological and pathological mechanical landscape. Importantly, three of these gradients were found to be nondurotactic for human adipose-derived stem cells (hASCs), allowing the presentation of a continuous range of stiffnesses in a single well without the confounding effect of differential cell migration. Using these nondurotactic gradient gels, stiffness-dependent hASC morphology, migration, and differentiation were studied. Finally, the mechanosensitive proteins YAP, Lamin A/C, Lamin B, MRTF-A, and MRTF-B were analyzed on these gradients, providing higher-resolution data on stiffness-dependent expression and localization.

Published
2017

41. Distance-dependent adhesion of vascular cells on biofunctionalized nanostructures

Author

Biela Sarah, Striegl Britta, Frey Kerstin, Spatz Joachim P., and Kemkemer Ralf

Subjects
cell adhesion, nanostructure, vascular cells, adhesive peptides, Medicine
Abstract

Cell-cell and cell-extracellular matrix (ECM) adhesion regulates fundamental cellular functions and is crucial for cell-material contact. Adhesion is influenced by many factors like affinity and specificity of the receptor-ligand interaction or overall ligand concentration and density. To investigate molecular details of cell-ECM and cadherins (cell-cell) interaction in vascular cells functional nanostructured surfaces were used Ligand-functionalized gold nanoparticles (AuNPs) with 6-8 nm diameter, are precisely immobilized on a surface and separated by non-adhesive regions so that individual integrins or cadherins can specifically interact with the ligands on the AuNPs. Using 40 nm and 90 nm distances between the AuNPs and functionalized either with peptide motifs of the extracellular matrix (RGD or REDV) or vascular endothelial-cadherins (VEC), the influence of distance and ligand specificity on spreading and adhesion of endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. We demonstrate that RGD-dependent adhesion of vascular cells is similar to other cell types and that the distance dependence for integrin binding to ECM-peptides is also valid for the REDV motif. VEC-ligands decrease adhesion significantly on the tested ligand distances. These results may be helpful for future improvements in vascular tissue engineering and for development of implant surfaces.

Published
2017
Full Text
View/download PDF

47. Covalent Adaptable Microstructures via Combining Two‐Photon Laser Printing and Alkoxyamine Chemistry: Toward Living 3D Microstructures.

Author

Jia, Yixuan, Spiegel, Christoph A., Welle, Alexander, Heißler, Stefan, Sedghamiz, Elaheh, Liu, Modan, Wenzel, Wolfgang, Hackner, Maximilian, Spatz, Joachim P., Tsotsalas, Manuel, and Blasco, Eva

Subjects
LASER printing, YOUNG'S modulus, MICROSTRUCTURE, EXCHANGE reactions, THREE-dimensional printing
Abstract

Manufacturing programmable materials, whose mechanical properties can be adapted on demand, is highly desired for their application in areas ranging from robotics, to biomedicine, or microfluidics. Herein, the inclusion of dynamic and living bonds, such as alkoxyamines, in a printable formulation suitable for two‐photon 3D laser printing is exploited. On one hand, taking advantage of the dynamic covalent character of alkoxyamines, the nitroxide exchange reaction is investigated. As a consequence, a reduction of the Young´s Modulus by 50%, is measured by nanoindentation. On the other hand, due to its "living" characteristic, the chain extension becomes possible via nitroxide mediated polymerization. In particular, living nitroxide mediated polymerization of styrene results not only in a dramatic increase of the volume (≈8 times) of the 3D printed microstructure but also an increase of the Young's Modulus by two orders of magnitude (from 14 MPa to 2.7 GPa), while maintaining the shape including fine structural details. Thus, the approach introduces a new dimension by enabling to create microstructures with dynamically tunable size and mechanical properties. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results