scholarly journals Elucidating nanoscale mechanical properties of diabetic human adipose tissue using atomic force microscopy

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J. K. Wenderott ◽  
Carmen G. Flesher ◽  
Nicki A. Baker ◽  
Christopher K. Neeley ◽  
Oliver A. Varban ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Metabolic Disease ◽  
Atomic Force Microscopy ◽  
Adipose Tissue ◽  
Elastic Modulus ◽  
Tissue Mechanics ◽  
Health Concern ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Impact

AbstractObesity-related type 2 diabetes (DM) is a major public health concern. Adipose tissue metabolic dysfunction, including fibrosis, plays a central role in DM pathogenesis. Obesity is associated with changes in adipose tissue extracellular matrix (ECM), but the impact of these changes on adipose tissue mechanics and their role in metabolic disease is poorly defined. This study utilized atomic force microscopy (AFM) to quantify difference in elasticity between human DM and non-diabetic (NDM) visceral adipose tissue. The mean elastic modulus of DM adipose tissue was twice that of NDM adipose tissue (11.50 kPa vs. 4.48 kPa) to a 95% confidence level, with significant variability in elasticity of DM compared to NDM adipose tissue. Histologic and chemical measures of fibrosis revealed increased hydroxyproline content in DM adipose tissue, but no difference in Sirius Red staining between DM and NDM tissues. These findings support the hypothesis that fibrosis, evidenced by increased elastic modulus, is enhanced in DM adipose tissue, and suggest that measures of tissue mechanics may better resolve disease-specific differences in adipose tissue fibrosis compared with histologic measures. These data demonstrate the power of AFM nanoindentation to probe tissue mechanics, and delineate the impact of metabolic disease on the mechanical properties of adipose tissue.

Atomic force microscopy-based nanomechanical characterization of kenaf fiber

2019 ◽  
Vol 54 (15) ◽  
pp. 2065-2071 ◽  
Author(s):  
M Subbir Parvej ◽  
Xinnan Wang ◽  
Joseph Fehrenbach ◽  
Chad A Ulven
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Adhesion Force ◽  
Fiber Surface ◽  
Gauge Length ◽  
Hibiscus Cannabinus ◽  
Kenaf Fiber ◽  
Force Microscopy ◽  
Atomic Force

Kenaf ( Hibiscus cannabinus L.) fiber is being extensively used as a reinforcement material in composites due to its excellent mechanical properties. To use this fiber more efficiently, it is necessary to understand its mechanical properties at micro/nano meter scale. Despite the evidence of some past studies to determine the elastic modulus of kenaf fiber, most of them were performed on fiber bundles. Bundle-based method to find the elastic moduli has some obvious issues of foreign materials being present, incorrect gauge length, and sample diameter due to void spaces. These issues pose as obvious hurdles to determine the elastic modulus accurately. In this study, individual kenaf micro fiber was used to find elastic modulus in the radial direction. The radial elastic modulus of the fiber was characterized by atomic force microscopy-based nanoindentation. To determine the radial elastic modulus from the force versus sample deformation data, the extended Johnson–Kendall–Roberts model was used which considered adhesion force from the fiber surface. The radial elastic modulus of the kenaf fiber was found to be 2.3 GPa.

Mapping of Nanoscale Mechanical Properties of Polymers in Quasi-static and Oscillatory Atomic Force Microscopy Modes

MRS Advances ◽  
2016 ◽  
Vol 1 (40) ◽  
pp. 2763-2768 ◽  
Author(s):  
Sergei Magonov ◽  
Marko Surtchev ◽  
John Alexander ◽  
Ivan Malovichko ◽  
Sergey Belikov
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Polymer Materials ◽  
Work Of Adhesion ◽  
Force Microscopy ◽  
Atomic Force ◽  
Time Dependencies ◽  
Force Curves ◽  
20 Nm

ABSTRACTRecent advances in studies of local mechanical properties of polymers with different atomic force microscopy techniques (contact, Hybrid and amplitude modulation modes) are described in interplay between experiment and theory. Analysis of force curves and time dependencies of probe response to sample compliance, which were recorded on a number of polymer materials at various temperatures, leads to quantitative mapping of specific mechanical properties (elastic modulus, work of adhesion, etc). High spatial resolution of elastic modulus mapping (10-20 nm) is illustrated in measurements of lamellar structures of several polymers. Challenges of examination of viscoelastic properties are pointed out and a possible solution is presented.

scholarly journals Ultrastructural and nanomechanical changes of the cornea following enzymatic degradation

2018 ◽  
Vol 2 (2) ◽  
pp. 24-29
Author(s):  
Ahmed Kazaili ◽  
Riaz Akhtar
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Enzymatic Degradation ◽  
Enzymatic Treatment ◽  
Force Microscopy ◽  
Collagen Organization ◽  
Atomic Force ◽  
Ocular Disorders ◽  
Porcine Cornea

Understanding of the ultrastructure and nanomechanical behavior of the cornea is important for a number of ocular disorders. In this study, atomic force microscopy (AFM) was used to determine nanoscale changes in the porcine cornea following enzymatic degradation. Diff erent concentrations of amylase were used to degrade the cornea. A reduction in elastic modulus at the nanoscale, along with disrupted collagen morphology, was observed following enzymatic treatment. This study highlights the interplay between mechanical properties and collagen organization in the healthy cornea.

In Situ Measurement of Elastic and Frictional Properties Using Atomic Force Microscopy

2021 ◽  
pp. 1-10
Author(s):  
Ngoc-Phat Huynh ◽  
Tuan-Em Le ◽  
Koo-Hyun Chung
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Force Microscopy ◽  
Frictional Properties ◽  
Atomic Force ◽  
Proposed Model ◽  
Significant Difference ◽  
Modulus Measurement

Atomic force microscopy (AFM) can determine mechanical properties, associated with surface topography and structure, of a material at the nanoscale. Force–indentation curves that depict the deformation of a target specimen as a function of an applied force are widely used to determine the elastic modulus of a material based on a contact model. However, a hysteresis may arise due to friction between the AFM tip and a specimen. Consequently, the normal force detected using a photodetector during extension and retraction could be underestimated and overestimated, respectively, and the extension/retraction data could result in a significant difference in the elastic modulus measurement result. In this study, elastic modulus and friction coefficient values were determined based on an in situ theoretical model that compensated for the effect of friction on force–indentation data. It validated the proposed model using three different polymer specimens and colloidal-tipped probes for the force–indentation curve and friction loop measurements. This research could contribute to the accurate measurement of mechanical properties using AFM by enhancing the interpretation of force–indentation curves with friction-induced hysteresis. Furthermore, the proposed approach may be useful for analyzing in situ relationships between mechanical and frictional properties from a fundamental tribological perspective.

scholarly journals Time- and Zinc-Related Changes in Biomechanical Properties of Human Colorectal Cancer Cells Examined by Atomic Force Microscopy

Biology ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 468
Author(s):  
Maria Maares ◽  
Claudia Keil ◽  
Leif Löher ◽  
Andreas Weber ◽  
Amsatou Andorfer-Sarr ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Cell Lines ◽  
Mechanical Response ◽  
Cultured Cells ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Impact ◽  
Ht 29

Monitoring biomechanics of cells or tissue biopsies employing atomic force microscopy (AFM) offers great potential to identify diagnostic biomarkers for diseases, such as colorectal cancer (CRC). Data on the mechanical properties of CRC cells, however, are still scarce. There is strong evidence that the individual zinc status is related to CRC risk. Thus, this study investigates the impact of differing zinc supply on the mechanical response of the in vitro CRC cell lines HT-29 and HT-29-MTX during their early proliferation (24–96 h) by measuring elastic modulus, relaxation behavior, and adhesion factors using AFM. The differing zinc supply severely altered the proliferation of these cells and markedly affected their mechanical properties. Accordingly, zinc deficiency led to softer cells, quantitatively described by 20–30% lower Young’s modulus, which was also reflected by relevant changes in adhesion and rupture event distribution compared to those measured for the respective zinc-adequate cultured cells. These results demonstrate that the nutritional zinc supply severely affects the nanomechanical response of CRC cell lines and highlights the relevance of monitoring the zinc content of cancerous cells or biopsies when studying their biomechanics with AFM in the future.

scholarly journals Nanoscale Mechanical Properties and Indentation Recovery of PI@GO Composites Measured Using AFM

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1020 ◽  
Author(s):  
Ji Zhou ◽  
Qiang Cai ◽  
Fu Xu
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Elastic Modulus ◽  
Young’S Modulus ◽  
Simple Solution ◽  
Force Microscopy ◽  
Solution Blending ◽  
Atomic Force ◽  
Blending Method

Polyimide@graphene oxide (PI@GO) composites were prepared by way of a simple solution blending method. The nanoscale hardness and Young’s modulus of the composites were measured using nanoindentation based on atomic force microscopy (AFM). A nanoscale hardness of ~0.65 GPa and an elastic modulus of ~6.5 GPa were reached with a load of ~55 μN. The indentation recovery on the surface of PI@GO was evaluated. The results show that relatively low GO content can remarkably improve the nanoscale mechanical properties of PI.

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.

scholarly journals Micro-mechanical properties of single high aspect ratio crystals

CrystEngComm ◽  
2019 ◽  
Vol 21 (38) ◽  
pp. 5738-5748 ◽  
Author(s):  
François S. Hallac ◽  
Ioannis S. Fragkopoulos ◽  
Simon D. Connell ◽  
Frans L. Muller
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Aspect Ratio ◽  
Single Crystal ◽  
High Aspect Ratio ◽  
New Method ◽  
Force Microscopy ◽  
Atomic Force

This work describes a new method to measure breakage strength and elastic modulus of single crystal cantilevers using atomic force microscopy.

scholarly journals Development of mechanical properties of regenerated cellulose beads during drying as investigated by atomic force microscopy

Soft Matter ◽  
2020 ◽  
Vol 16 (28) ◽  
pp. 6457-6462 ◽  
Author(s):  
Hailong Li ◽  
Katarzyna Mystek ◽  
Lars Wågberg ◽  
Torbjörn Pettersson
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Regenerated Cellulose ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gel Beads ◽  
Cellulose Gel

We probe the elastic modulus of cellulose gel beads during drying by indentation with atomic force microscopy.

Extracting elastic properties and prestress of a cell using atomic force microscopy

2009 ◽  
Vol 24 (3) ◽  
pp. 1167-1171 ◽  
Author(s):  
C.Y. Zhang ◽  
Y.W. Zhang
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Analytical Solution ◽  
Cell Membrane ◽  
Soft Phase ◽  
Force Microscopy ◽  
Apparent Modulus ◽  
Atomic Force ◽  
A Cell

An analytical solution was derived for the indentation of a cell using atomic force microscopy. It was found that the contribution of the cell membrane to the overall indentation stiffness is dependent on the size of the indenter. When a small indenter [for example, an atomic force microscopy (AFM) tip] is used to probe the mechanical properties of cells, the cell membrane and its prestress were important in interpreting indentation data. The solution allows the partition of contributions from the membrane and the interior soft phase. The apparent elastic modulus of the cell and the prestress of the cell membrane can be extracted. In addition, the modulus of the cell membrane could be estimated from the extracted apparent modulus if the interior soft phase of the cell was known and vice versa. However, when a large indenter is used (for example, a microbead attached to the cantilever beam of the AFM), the contribution of the cell membrane is negligible.

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