Determination of Single-Bond Forces from Contact Force Variances in Atomic Force Microscopy

Williams, John M.; Han, and Taejoon; Beebe, Thomas P.

doi:10.1021/la950500j

Cited by 140 publications

(157 citation statements)

References 24 publications

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“…Moreover, in a long-range approach, surface appendages may be less important, as the concept of distance between bacteria and substratum surfaces is lost upon close approach. Long-range Lifshitz-Van der Waals adhesion forces can be derived from contact angles with liquids on the interacting surfaces and surface thermodynamic modeling (25,26) or decoupling of AFM adhesion force measurements using Poisson analysis (27)(28)(29)(30). However, among different strains, long-range adhesion forces vary considerably less than short-range forces (27)(28)(29)(30).…”

Section: Discussionmentioning

confidence: 99%

Nanoscale Cell Wall Deformation Impacts Long-Range Bacterial Adhesion Forces on Surfaces

Chen

Harapanahalli

Busscher

et al. 2014

Appl Environ Microbiol

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Adhesion of bacteria occurs on virtually all natural and synthetic surfaces and is crucial for their survival. Once they are adhering, bacteria start growing and form a biofilm, in which they are protected against environmental attacks. Bacterial adhesion to surfaces is mediated by a combination of different short-and long-range forces. Here we present a new atomic force microscopy (AFM)-based method to derive long-range bacterial adhesion forces from the dependence of bacterial adhesion forces on the loading force, as applied during the use of AFM. The long-range adhesion forces of wild-type Staphylococcus aureus parent strains (0.5 and 0.8 nN) amounted to only one-third of these forces measured for their more deformable isogenic ⌬pbp4 mutants that were deficient in peptidoglycan cross-linking. The measured long-range Lifshitz-Van der Waals adhesion forces matched those calculated from published Hamaker constants, provided that a 40% ellipsoidal deformation of the bacterial cell wall was assumed for the ⌬pbp4 mutants. Direct imaging of adhering staphylococci using the AFM peak force-quantitative nanomechanical property mapping imaging mode confirmed a height reduction due to deformation in the ⌬pbp4 mutants of 100 to 200 nm. Across naturally occurring bacterial strains, long-range forces do not vary to the extent observed here for the ⌬pbp4 mutants. Importantly, however, extrapolating from the results of this study, it can be concluded that long-range bacterial adhesion forces are determined not only by the composition and structure of the bacterial cell surface but also by a hitherto neglected, small deformation of the bacterial cell wall, facilitating an increase in contact area and, therewith, in adhesion force. Bacteria adhere to virtually all natural and synthetic surfaces (1, 2), as adhesion is crucial for their survival. Bacterial adhesion to surfaces is followed by their growth and constitutes the first step in the formation of a biofilm, in which organisms are protected against antimicrobial treatment and environmental attacks. Accordingly, the biofilm mode of growth is highly persistent and biofilms are notoriously hard to remove, causing major problems in many industrial and biomedical applications, with high associated costs. On the other hand, biofilms can be beneficial, too, as in the bioremediation of soil, for instance. Surface thermodynamics and (extended) DLVO (Derjaguin and Landau, Verwey, and Overbeek) approaches have been amply applied in current microbiology to outline that bacterial adhesion to surfaces is mediated by an interplay of different fundamental physicochemical interactions, including Lifshitz-Van der Waals, electric double-layer, and acid-base forces (3-5). Assorted according to their different effective ranges, these different fundamental interactions can be alternatively categorized into two groups, short-range and long-range forces (6), that act over distances of a few nm up to 10s of nm, respectively.Long-range adhesion forces are generally associated with Lifshitz-Van der ...

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Section: Discussionmentioning

confidence: 99%

Nanoscale Cell Wall Deformation Impacts Long-Range Bacterial Adhesion Forces on Surfaces

Chen

Harapanahalli

Busscher

et al. 2014

Appl Environ Microbiol

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“…The attempt throughout this work was to minimize damage to the proteins which could occur by repeated pressure and forced unbinding by the probe. An alternative method for analyzing and distinguishing single chemical bond forces from a smaller number of SFM force curve measurements has recently been presented by Beebe et al [21,40]. This method applies Poisson statistics to compare mean forces with force variances for several data sets.…”

Section: Discussionmentioning

confidence: 99%

“…This analysis was extended to include the relative contribution of nonspecific interactions to observed force values [40]. In the absence of non-specific interactions, the intercept of the μ(σ 2 ) plot is zero.…”

Section: Discussionmentioning

confidence: 99%

Feasibility of measuring antigen–antibody interaction forces using a scanning force microscope

Stuart

Hlady

1999

Colloids and Surfaces B: Biointerfaces

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The molecular affinity scanning force microscopy (MASFM) described in this study was developed in an effort to test the possibility of antigen-antibody binding measurement using forceseparation distance profiles. The MASFM configuration was comprised of a spherical glass bead as an MASFM probe, to which the fluorescein antigen has been covalently attached, and a silicon dioxide-based substrate, to which the antifluorescyl IgG antibody was covalently bound. The bead was glued to the tip of a commercial SFM cantilever. Adhesion forces have been measured between two different specific antigen-antibody pairs and between nonspecific surfaces bearing only glycidoxypropylsilane immobilization chemistry. In force-separation (F-s) measurements, nonspecific forces displayed relatively few force discontinuities and mean adhesion forces lower than those found for specific antigen-antibody measurements. Force-separation profiles measured between specific antigen-antibody pairs showed many discontinuities and had higher mean forces. Positive controls revealed that the mean forces were slightly reduced by the addition of free ligand. The magnitude of mean forces did not correlate with the respective activation enthalpies of the proteins, as would be expected. At lower force values the force histograms for the specific pairs and for positive controls were indistinguishable. None of the force-separation data sets could fit a Poisson discrete-force model. This statistical analysis showed a large relative contribution from nonspecific interactions. It is concluded that the use of the large sphere as an SFM probe is counterproductive: while the large sphere does sample a larger number of specific interactions during each measurement, it also samples at the same time a large proportion of nonspecific forces. The presence of the nonspecific force contributions is likely due to the deformation of the polymerized GPS spacer layer which is thought to be delaminated from the surface upon the application of tension across the specific antigen-antibody bonds.

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“…The authors show that the effective force resolution and hence the possibility to detect quantized adhesion forces decreases with increasing solvent surface energy, increasing tip radius, and decreasing binding probability. In other works the determination of the single bond is achieved following a method based on the assumption that the ruptures obey Poisson statistics [125,391]. In this method chemical bonds, hydrogen bonds and van der Waals force are considered as specific interactions yielding a total adhesion force F ad that is the sum of any possible discrete bond.…”

Section: Determination Of Hamaker Constants Adhesion and Surface Enementioning

confidence: 99%

Force measurements with the atomic force microscope: Technique, interpretation and applications

Butt

Cappella

Kappl

2005

Surface Science Reports

3,151

2,949

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Determination of Single-Bond Forces from Contact Force Variances in Atomic Force Microscopy

Cited by 140 publications

References 24 publications

Nanoscale Cell Wall Deformation Impacts Long-Range Bacterial Adhesion Forces on Surfaces

Nanoscale Cell Wall Deformation Impacts Long-Range Bacterial Adhesion Forces on Surfaces

Feasibility of measuring antigen–antibody interaction forces using a scanning force microscope

Force measurements with the atomic force microscope: Technique, interpretation and applications

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