scholarly journals Irreversible chemical afm-fishing for the detection of low-copied proteins

2014 ◽  
Vol 60 (1) ◽  
pp. 28-50 ◽  
Author(s):  
Yu.D. Ivanov ◽  
V.V. Danichev ◽  
T.O. Pleshakova ◽  
I.D. Shumov ◽  
V.S. Ziborov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Atomic Force Microscopy ◽  
Theoretical Model ◽  
Horseradish Peroxidase ◽  
Bulk Solution ◽  
Irreversible Binding ◽  
Chip Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Low Concentrations

The atomic-force microscopy-based method of irreversible chemical AFM-fishing (AFM-IF ) has been developed for the detection of proteins at ultra-low concentrations in solution. Using this method, a very low concentration of horseradish peroxidase (HRP) protein (10 17 M) was detected in solution. A theoretical model that allows the description of obtained experimental data, is proposed. This model takes into consideration both the transport of the protein from the bulk solution onto the AFM-chip surface and its irreversible binding to the activated area.

Atomic Force Microscopy Structural Characterization of Polyaniline Thin Film Sensors

1994 ◽  
Vol 338 ◽  
Author(s):  
Jack Y. Josefowicz ◽  
Frederick G. Yamagishi ◽  
Camille I. van Ast
Keyword(s):  
Atomic Force Microscopy ◽  
Response Time ◽  
Gold Electrodes ◽  
Lower Sensitivity ◽  
Force Microscopy ◽  
Thin Film Sensors ◽  
Atomic Force ◽  
Polymer Sensors ◽  
Modeling Analysis ◽  
Low Concentrations

ABSTRACTUsing Tapping Mode Atomic Force Microscopy (TMAFM), the surface structure was determinedfor polymer sensors which incorporated polyaniline (PAn) films that were deposited electrochemically across narrow insulating gaps between interdigitated gold electrodes. The sensitivity and response time for such sensors, which can be used for the detection of low levels of gases and low concentrations of impurities in liquid media critically dependon the quality and structure of the polymer film in the gap region between the gold electrodes. TMAFM images of the PAn films ranging in thickness between ≈1.5μtmand ≈5μm reveal that films approaching 5μm (typically used in such sensors) develop deep cracks at the edges and along the length of the Au electrodes. Thecracks, which appear to be a consequence of stress build-up in thick films, can lead to reliability problems and inferior sensor performance. Simple modeling analysis of cracked films indicates that they can lower sensitivity and increase response time. TMAFM images of sensors with thinner ≈2.5μm PAn films show no cracks as well as continuous PAn bridges across the gap between Au electrodes. Analyses of TMAFM images are presented and compared for thin and thick film PAn sensors.

scholarly journals Atomic force microscopy study of nanoindentation deformation and indentation size effect in MgO crystals

1999 ◽  
Vol 14 (10) ◽  
pp. 3973-3982 ◽  
Author(s):  
K. Sangwal ◽  
P. Gorostiza ◽  
J. Servat ◽  
F. Sanz
Keyword(s):  
Experimental Data ◽  
Plastic Deformation ◽  
Atomic Force Microscopy ◽  
Size Effect ◽  
Deformation Zone ◽  
Indentation Size Effect ◽  
Indentation Size ◽  
Depth Of Penetration ◽  
Force Microscopy ◽  
Atomic Force

The dependences of various nanoindentation parameters, such as depth of penetration d, indentation diameter a, deformation zone radius R, and height h of hills piled up around indents, on applied load were investigated for the initial (unrecovered) stage of indentation of the (100) cleavage faces of MgO crystals by square pyramidal Si tips for loads up to 10 μN using atomic force microscopy. The experimental data are analyzed using theories of elastic and plastic deformation. The results revealed that (i) a, R, and h linearly increase with d; (ii) the development of indentation size and deformation zone and the formation of hills are two different processes; (iii) the load dependence of nanohardness shows the normal indentation size effect (i.e., the hardness increases with a decrease in load); and (iv) there is an absence of plastic deformation involving the formation of slip lines around the indentations. It is found that Johnson's cavity model of elastic–plastic boundary satisfactorily explains the experimental data. The formation of hills around indentations is also consistent with a new model (i.e., indentation crater model) based on the concept of piling up of material of indentation cavity as hills.

scholarly journals Atomic force microscopy fishing of gp120 on immobilized aptamer and its mass spectrometry identification

2015 ◽  
Vol 61 (3) ◽  
pp. 363-372 ◽  
Author(s):  
N.S. Bukharina ◽  
Yu.D. Ivanov ◽  
T.O. Pleshakova ◽  
P.A. Frantsuzov ◽  
E.Yu. Andreeva ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Atomic Force Microscopy ◽  
Protein Detection ◽  
Target Protein ◽  
Mass Spectrometry Analysis ◽  
Molecular Probe ◽  
Bulk Solution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mass Spectrometry Identification

A method of atomic force microscopy-based fishing (AFM fishing) has been developed for protein detection in the analyte solution using a chip with an immobilized aptamer. This method is based on the biospecific fishing of a target protein from a bulk solution onto the small AFM chip area with the immobilized aptamer to this protein used as the molecular probe. Such aptamer-based approach allows to increase an AFM image contrast compared to the antibody-based approach. Mass spectrometry analysis used after the biospecific fishing to identify the target protein on the AFM chip has proved complex formation. Use of the AFM chip with the immobilized aptamer avoids interference of the antibody and target protein peaks in a mass spectrum.

Atomic Force Microscopy Contact Mode Study on Ultra High Molecular Weight Polyethylene

2005 ◽  
Vol 874 ◽  
Author(s):  
Yifang Cao ◽  
Jikou Zhou ◽  
Oludele Popoola ◽  
Dal F. Swarts ◽  
Wole Soboyejo
Keyword(s):  
Experimental Data ◽  
Molecular Weight ◽  
Atomic Force Microscopy ◽  
Young’S Modulus ◽  
High Molecular Weight ◽  
Work Of Adhesion ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Ultra High Molecular Weight

AbstractThis paper presents the results of contact mode atomic force microscopy (AFM) study on the nanoscale Young's modulus and work of adhesion of ultra high molecular weight polyethylene (UHMWPE). Cryoultramicrotomed surfaces of UHMWPE were scanned using the contact mode of AFM. Fibril regions are commonly found on the sample, however, a non-fibril particulate region was also found. AFM force displacement curves were obtained for the sample. The JKR theory and Maugis Dugdale model were used for the analysis. A good fitting between the theories and experimental data was found. The nanoscale Young's modulus and work of adhesion of UHMWPE extracted from the experimental data were in reasonably good agreement with the values reported in other literatures.

scholarly journals Mechanical properties of the surface of gastric epithelial cells in patients with oncologic pathology

2021 ◽  
pp. 152-159
Author(s):  
A. S. Shaforost ◽  
E. V. Voropaev ◽  
S. L. Achinovich ◽  
R. A. Silin
Keyword(s):  
Experimental Data ◽  
Gastric Cancer ◽  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Epithelial Cells ◽  
Tumor Cells ◽  
Cortical Layer ◽  
Gastric Epithelial Cells ◽  
Force Microscopy ◽  
Atomic Force

Objective: to study the efficiency of the application of atomic force microscopy for the identification of differences in the structural and mechanical properties of gastric epithelial cells in normal conditions and in gastric cancer.Material and methods. The structural and mechanical properties of the membrane of the epithelial cells of the gastric mucosa in 7 patients with gastric cancer were assessed using atomic force microscopy in contact mode.Results. The comparison of the size and shape of gastric mucous cells (GLC), their healthy and tumor areas has showed that in both the cases they have a slightly elongated rounded shape and similar dimensions: length × width × height of the cell is norm (in μm): 7.5 × 6.8 × 0.6, and in case of oncologic pathology (in μm): 7.2 × 6.9 × 1.0. Tumor cells are characterized by a 13% increase in their surface roughness compared to normal epithelial cells. The lateral force microscopy method allows of obtaining data on the structure of the submembrane cortical layer of the cell cytoskeleton. According to experimental data, a 2.48-fold decrease in the value of the friction force (Fl) in epithelial cells from healthy areas of the coolant indicates increased density and integrity of the cortical layer of the cytoskeleton in normal conditions compared to those of tumor cells.Conclusion. The analysis of the experimental data has found that tumor cells from the gastric mucosa differ from healthy cells in terms of their nanomechanical properties: they are characterized by a rougher surface, which consists of fewer structural elements of a larger size. The work has showed the interrelation of the indicators of the frictional properties of the cell surface: the values of the friction forces and the roughness of the friction map.

scholarly journals Nanoscale spatial mapping of mechanical properties through dynamic atomic force microscopy

2019 ◽  
Vol 10 ◽  
pp. 1332-1347 ◽  
Author(s):  
Zahra Abooalizadeh ◽  
Leszek Josef Sudak ◽  
Philip Egberts
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Pyrolytic Graphite ◽  
Spatial Mapping ◽  
Atomic Steps ◽  
Force Microscopy ◽  
Atomic Force ◽  
Quantitative Results

Dynamic atomic force microscopy (AFM) was employed to spatially map the elastic modulus of highly oriented pyrolytic graphite (HOPG), specifically by using force modulation microscopy (FMM) and contact resonance (CR) AFM. In both of these techniques, a variation in the amplitude signal was observed when scanning over an uncovered step edge of HOPG. In comparison, no variation in the amplitude signal was observed when scanning over a covered step on the same surface. These observations qualitatively indicate that there is a variation in the elastic modulus over uncovered steps and no variation over covered ones. The quantitative results of the elastic modulus required the use of FMM, while the CR mode better highlighted areas of reduced elastic modulus (although it was difficult to convert the data into a quantifiable modulus). In the FMM measurements, single atomic steps of graphene with uncovered step edges showed a decrease in the elastic modulus of approximately 0.5%, which is compared with no change in the elastic modulus for covered steps. The analysis of the experimental data taken under varying normal loads and with several different tips showed that the elastic modulus determination was unaffected by these parameters.

A Comparative Study on the Self-Assembly of Peptide TGV-9 by In Situ Atomic Force Microscopy

2020 ◽  
Vol 26 (2) ◽  
pp. 319-325
Author(s):  
Yaping Li ◽  
Na Li ◽  
Lei Wang ◽  
Qinhua Lu ◽  
Xiang Ji ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Self Assembly ◽  
The Self ◽  
Peptide Sequence ◽  
Bulk Solution ◽  
Free Standing ◽  
Atomic Lattice ◽  
Force Microscopy ◽  
Atomic Force

AbstractPrevious studies of amyloid diseases reported that the aggregating proteins share a similar conserved peptide sequence which can form the cross-β-sheet-containing nanostructures like nanofilaments. The template-assisted self-assembly (TASA) of peptides on inorganic substrates with different hydrophilicity could be an alternative approach to shed light on the fibrillization mechanism of proteins/peptides in vivo. To figure out the effect of interfaces on amyloid aggregation, we herein employed in situ atomic force microscopy (AFM) to investigate the self-assembling of a Parkinson disease-related core peptide sequence (TGV-9) on a hydrophobic liquid–solid interface via real-time observation of the dynamic fibrillization process. The results show that TGV-9 forms one-dimensional nanostructures on the surface of highly ordered pyrolytic graphite (HOPG) with three preferred growth orientations, which are consistent with the atomic lattice of HOPG, indicating an epitaxial growth or TASA. Conversely, the nanostructures formed in bulk solution can be free-standing nanofilaments, and the fibrillization mechanism is different from that on HOPG. These results could not only deepen the understanding of the protein/peptide aggregation mechanism but also benefit for the early diagnosis and clinic treatment of related diseases.

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