scholarly journals Lipid specificity of the immune effector perforin

2020 ◽  
Author(s):  
Adrian W. Hodel ◽  
Jesse A. Rudd-Schmidt ◽  
Joseph A. Trapani ◽  
Ilia Voskoboinik ◽  
Bart W. Hoogenboom
Keyword(s):  
Pore Formation ◽  
Immune Effector ◽  
Force Microscopy ◽  
Atomic Force ◽  
Residual Protein ◽  
Dense Membrane ◽  
Lipid Species ◽  
Infected Cells ◽  
Lipid Specificity ◽  
Insight Into

AbstractPerforin is a pore forming protein used by cytotoxic T lymphocytes to remove cancerous or virus-infected cells during immune response. During the response, the lymphocyte membrane becomes refractory to perforin function by accumulating densely ordered lipid rafts and externalizing negatively charged lipid species. The dense membrane packing lowers the capacity of perforin to bind, and negatively charged lipids scavenge any residual protein before pore formation. Using atomic force microscopy on model membrane systems, we here provide insight into the molecular basis of perforin lipid specificity.

scholarly journals Dental calculus: Nano-characterization

2012 ◽  
Vol 59 (3) ◽  
pp. 154-159
Author(s):  
Djurica Grga ◽  
Marina Marjanovic ◽  
Igor Hut ◽  
Bojan Dzeletovic ◽  
Djuro Koruga
Keyword(s):  
Magnetic Field Gradient ◽  
Dental Calculus ◽  
Oral Diseases ◽  
Force Microscopy ◽  
Atomic Force ◽  
Light Matter Interaction ◽  
The Magnetic Field ◽  
Very High ◽  
Insight Into

Emerging technologies and new nanoscale information have potential to transform dental practice by improving all aspects of diagnostics and therapy. Nanocharacterization allows understanding of oral diseases at molecular and cellular levels which eventually can increase the success of prevention and treatment. Opto-magnetic spectroscopy (OMS) is a promising new technique based on light-matter interaction which allows insight into the quantum state of matter. Since biomolecules and tissues are usually paramagnetic or diamagnetic materials it is possible to determine the dynamics of para-and diamagnetism at different teeth structures using that method. The topography of the surface of a sample can be obtained with a very high resolution using atomic force microscopy (AFM), which allows observation of minimal changes up to 10 nm, while magnetic force microscopy (MFM) is used to record the magnetic field gradient and its distribution over the surface of a sample. The aim of this study was to determine the possibility of AFM and MFM for the characterization of dental calculus, and a potential application of OMS for the detection of subgingival dental calculus.

scholarly journals Quantitative atomic force microscopy provides new insight into matrix vesicle mineralization

2019 ◽  
Vol 667 ◽  
pp. 14-21 ◽  
Author(s):  
Justin S. Plaut ◽  
Agnieszka Strzelecka-Kiliszek ◽  
Lukasz Bozycki ◽  
Slawomir Pikula ◽  
René Buchet ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Matrix Vesicle ◽  
Force Microscopy ◽  
Atomic Force ◽  
Insight Into

Insight into the Deformation Mechanisms under a Sharp Contact Loading in Glass by Atomic Force Microscopy

2005 ◽  
Vol 904 ◽  
Author(s):  
Tanguy Rouxel ◽  
Satoshi Yoshida ◽  
Haixia Shang ◽  
Jean-Christophe Sangleboeuf
Keyword(s):  
Atomic Force Microscopy ◽  
Contact Area ◽  
Elastic Recovery ◽  
Residual Deformation ◽  
Constitutive Law ◽  
Indentation Creep ◽  
Contact Loading ◽  
Force Microscopy ◽  
Atomic Force ◽  
Insight Into

AbstractThe response of a material to a sharp contact loading, as in the case of Vickers indentation for instance, provides a unique insight into the material constitutive law, including elastic and irreversible deformation parameters as well. However, under such peculiar thermodynamical and mechanical conditions (the mean contact pressure on the contact area reaches values typically higher than 1 GPa, corresponding to the hardness of the material) the deformation processes are complex and the matter located just beneath and around the contact area may experience some structural changes and behave in a way different to the expected - or known - macroscopic behaviour. It is showed in this study by means of detailed topological investigations of the residual indentations by Atomic Force Microscopy (AFM) that the elastic recovery typically represents 50 to 70 % of the indentation volume at maximum load and that the densification contribution may reach 90 % of the residual deformation volume. Besides, most glasses exhibit indentation-creep phenomena, which become significant over time scale of few minutes because of a pronounced shear-thinning behavior..

Numerical Analysis of the Band Excitation AFM Method: Examining the Characteristics of the Excitation Signals and the Corresponding Response Behavior at the Cantilever Tip

2011 ◽  
Author(s):  
Adam U. Kareem ◽  
Santiago D. Solares
Keyword(s):  
Atomic Force Microscopy ◽  
Initial Step ◽  
Phase Content ◽  
Frequency Content ◽  
Response Behavior ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sinc Functions ◽  
Insight Into ◽  
Excitation Method

We present numerical simulations of a recently developed atomic force microscopy (AFM) technique known as the Band Excitation Method, developed by Jesse et al. [2007 Nanotechnology 18 435503]. With this technique an AFM microcantilever is simultaneously excited and the response measured over a continuum band of frequencies. The purpose of this work is to introduce an analytical model providing insight into the dynamics of the Band Excitation Method, which can help in the translation of the acquired signals into sample properties. As an initial step we examine the cantilever response to two distinct excitation signals, the chirp and sinc functions, both of which have uniform frequency content, differing only in the phase content.

Relationship Between Spectroscopic and Structural Properties of Poly(meta/para Phenylene)

1999 ◽  
Vol 598 ◽  
Author(s):  
Cherif. Dridi ◽  
Joël. Davenas ◽  
Ahmed. Touhami ◽  
Hafedh. Ben Ouada ◽  
Hassen. Mâaref ◽  
...  
Keyword(s):  
Conjugated Polymer ◽  
Quantum Confinement ◽  
Blue Shift ◽  
Film Morphology ◽  
Energy Band Gap ◽  
Paramagnetic Resonance ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electron Paramagnetic ◽  
Insight Into

ABSTRACTWe have used electron paramagnetic resonance (EPR) spectroscopy for investigating the properties of spins, such as those carried by polarons which carry both spin and charge in an electrosynthesized poly (meta/para phenylene) PMPP.Indeed, the study of their mobility provides an insight into the charge transport properties of the conjugated polymer in a microscopic scale.Moreover, we report a correlation between thin film morphology, chainlength and optical gap.Particularly, we show a blue shift upon decreasing chainlength. Furthermore, we have observed a blue shift of the energy band gap with the decrease of the surface grain size deduced from atomic force microscopy (AFM) analyses. This result has been explained in terms of quantum confinement.

scholarly journals Atomic force microscopy of phase separation on ruptured, giant unilamellar vesicles

2018 ◽  
Author(s):  
Yanfei Jiang ◽  
Guy M. Genin ◽  
Kenneth M. Pryse ◽  
Elliot L. Elson
Keyword(s):  
Atomic Force Microscopy ◽  
Phase Separation ◽  
Model Systems ◽  
Study Phase ◽  
Dark Phase ◽  
Giant Unilamellar Vesicles ◽  
Unilamellar Vesicles ◽  
Force Microscopy ◽  
Atomic Force ◽  
Lipid Species

AbstractGiant unilamellar vesicles (GUVs) and supported lipid bilayers (SLBs) are synthetic model systems widely used in biophysical studies of lipid membranes. Phase separation behaviors of lipid species in these two model systems differ due to the lipid-substrate interactions that are present only for SLBs. Therefore, GUVs are believed to resemble natural cell membranes more closely, and a very large body of literature focuses on applying nano-characterization techniques to quantify phase separation on GUVs. However, one important technique, atomic force microscopy (AFM), has not yet been used successfully to study phase separation on GUVs. In the present study, we report that in binary systems, certain phase domains on GUVs retain their original shapes and patterns after the GUVs rupture on glass surfaces. This enabled AFM experiments on phase domains from binary GUVs containing 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) and either 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC). These DLPC/DSPC and DLPC/DPPC GUVs both presented two different gel phases, one of which (bright phase) included a relatively high concentration of DiI-C20 but excluded Bodipy-HPC, and the other of which (dark phase) excluded both probes. The bright phases are of interest because they seem to stabilize dark phases against coalescence. Results suggested that the gel phases labeled by DiI-C20 in the DLPC/DSPC membrane, which surround the dark gel phase, is an extra layer of membrane, indicating a highly curved structure that might stabilize the interior dark domains. This phenomenon was not found in the DLPC/DPPC membrane. These results show the utility of AFM on collapsed GUVs, and suggest a possible mechanism for stabilization of lipid domains.

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