scholarly journals “May the Force Be with You!” Force–Volume Mapping with Atomic Force Microscopy

ACS Omega ◽  
2021 ◽  
Author(s):  
Olajumoke H. Olubowale ◽  
Shanta Biswas ◽  
Golam Azom ◽  
Benjamin L. Prather ◽  
Samuel D. Owoso ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Volume

Quantitative Mapping of Local Mechanical Properties of Living Cells at Near-Physiological Conditions Using Multi-Harmonic Atomic Force Microscopy

2012 ◽  
Author(s):  
Alexander Cartagena ◽  
Wen-Horng Wang ◽  
Robert L. Geahlen ◽  
Arvind Raman
Keyword(s):  
Atomic Force Microscopy ◽  
Living Cells ◽  
Cellular Biology ◽  
Force Microscopy ◽  
Nanomechanical Properties ◽  
Physiological Conditions ◽  
Atomic Force ◽  
Quantitative Mapping ◽  
Force Volume ◽  
Force Displacement

Measurements of local nanomechanical properties of living cells recently have become extremely important for the cellular biology and biomechanics communities [1]. The measurement of progressive variations in viscoelastic properties of living cells in their native physiological liquid environments can provide significant insight to the mechanistic processes underpinning morphogenesis, mechano-transduction, motility, metastasis, aging, etc. Atomic Force Microscopy (AFM) based biomechanical assays have the unique advantage of resolving/mapping spatially the local nanomechanical properties over the cell surface. However current methods using standard force-volume, force displacement curves [2–3] are very low resolution and low speed making them completely incompatible for biomechanical assays of living cells.

scholarly journals Investigating the biomechanical properties of streptococcal polysaccharide capsules using atomic force microscopy

2019 ◽  
Author(s):  
H Marshall ◽  
S Aguayo ◽  
M Kilian ◽  
FC Petersen ◽  
L Bozec ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Biomechanical Properties ◽  
Bacterial Strains ◽  
Biophysical Properties ◽  
Adhesive Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Virulence Potential ◽  
Force Volume ◽  
Polysaccharide Capsules

AbstractIn common with many bacterial pathogens, Streptococcus pneumoniae has a polysaccharide capsule, which facilitates immune evasion and is a key virulence determinant. However, recent data has shown that the closely related Streptococcus mitis can also express polysaccharide capsules including those with an identical chemical structure to S. pneumoniae capsular serotypes. We have used atomic force microscopy (AFM) techniques to investigate the biophysical properties of S. mitis and S. pneumoniae strains expressing the same capsular serotypes that might relate to their differences in virulence potential. When comparing S. mitis and S. pneumoniae strains with identical capsule serotypes S. mitis strains were more susceptible to neutrophil killing and imaging using electron microscopy and AFM demonstrated significant morphological differences. Force-volume mapping using AFM showed distinct force-curve profiles for the centre and edge areas of encapsulated S. pneumoniae and S. mitis strains. This “edge effect” was not observed in the unencapsulated streptococcal strains and in an unencapsulated Staphylococcus aureus strain, and therefore was a direct representation of the mechanical properties of the bacterial capsule. When two strains of S. mitis and S. pneumoniae expressed an identical capsular serotype, they presented also similar biomechanical characteristics. This would infer a potential relationship between capsule biochemistry and nanomechanics, independent of the bacterial strains. Overall, AFM was an effective tool to explore the biophysical properties of bacterial capsules of living bacteria by reproducibly quantifying the elastic and adhesive properties of bacterial cell surfaces. Using AFM to investigate capsule differences over a wider range of strains and capsular serotypes of streptococci and correlate the data with phenotypic differences will elucidate how the biophysical properties of the capsule can influence its biological role during infection.

scholarly journals Toward Accurate Quantitative Elasticity Mapping of Rigid Nanomaterials by Atomic Force Microscopy: Effect of Acquisition Frequency, Loading Force, and Tip Geometry

Nanomaterials ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 616 ◽  
Author(s):  
Guanghong Zeng ◽  
Kai Dirscherl ◽  
Jørgen Garnæs
Keyword(s):  
Plastic Deformation ◽  
Atomic Force Microscopy ◽  
High Frequency ◽  
Force Microscopy ◽  
Imaging Capability ◽  
Atomic Force ◽  
Force Resolution ◽  
Force Volume ◽  
Tip Radius ◽  
Elasticity Measurements

Atomic force microscopy (AFM) has emerged as a popular tool for the mechanical mapping of soft nanomaterials due to its high spatial and force resolution. Its applications in rigid nanomaterials, however, have been underexplored. In this work, we studied elasticity mapping of common rigid materials by AFM, with a focus on factors that affect the accuracy of elasticity measurements. We demonstrated the advantages in speed and noise level by using high frequency mechanical mapping compared to the classical force volume mapping. We studied loading force dependency, and observed a consistent pattern on all materials, where measured elasticity increased with loading force before stabilizing. Tip radius was found to have a major impact on the accuracy of measured elasticity. The blunt tip with 200 nm radius measured elasticity with deviation from nominal values up to 13% in different materials, in contrast to 122% by the sharp tip with 40 nm radius. Plastic deformation is believed to be the major reason for this difference. Sharp tips, however, still hold advantages in resolution and imaging capability for nanomaterials.

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