Chemical bonds studied with functionalized atomic force microscopy tips

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

doi:10.1016/0003-2670(94)00671-8

Cited by 127 publications

(157 citation statements)

References 29 publications

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“…A plot of variance against mean force should then be linear with a slope of F= σ 2 /μ. Convergence calculations showed that, for similar types of measurements, stable values of F could be obtained from as little as ten to 45 repetitions per data set [21].…”

Section: Discussionmentioning

confidence: 88%

“…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%

“…The antibody surface was fabricated using a self-assembled monolayer (SAM) bearing amine-reactive groups to which the antibodies were covalently bound. SAM techniques have been used by other groups as well to immobilize thiol-containing molecules, such as DNA [19] or functionalized amphiphiles [21], to a gold-coated surface. There is, however, a concern with using noncovalently bound molecules due to their ability to desorb during the experiment.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Stuart

Hlady

1999

Colloids and Surfaces B: Biointerfaces

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“…Interestingly, these results directly contradict the common assumption that the strength of the multiple bond is just a linear combination of the strength of individual bonds. This assumption even served as a basis for a published method of using Poisson statistics analysis for extracting the strength of a single bond from multiple bond strength measurements [29]. Kinetic model [66], as well as experimental measurements [67] prove that the true bond strength does not scale linearly with the bond number; therefore researchers should avoid using the Poisson statistics-based technique for data analysis and instead must use the full kinetic description.…”

Section: Dynamic Force Spectroscopy Of Tether-based Systemsmentioning

confidence: 99%

Chemical force microscopy of chemical and biological interactions

Noy

2006

Surface & Interface Analysis

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Interactions between chemical functionalities define outcomes of the vast majority of important events in chemistry, biology and materials science. Chemical Force Microscopy (CFM)-a technique that uses direct chemical functionalization of AFMprobes with specific functionalities -allows researchers to investigate these important interactions directly. We review the basic principles of CFM, some examples of its application, and theoretical models that provide the basis for understanding the experimental results. We also emphasize application of modern kinetic theory of non-covalent interactions strength to the analysis of CFM data.

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“…Thus, if the AFM probe tip and the substrate are modified chemically with selfassembled monolayers (SAMs) 6,7 terminating with target functional groups, the intermolecular force in their molecular pairs can be evaluated by force-curve measurements in appropriate solvents by AFM. [8][9][10][11][12][13][14][15][16][17][18][19]36 Furthermore, the individual force for a variety of intermolecular forces at a single-molecule level can also be evaluated by statistical analyses of the forces obtained by repetitive adhesion force measurements. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]37,38 In our previous studies, we measured specific intermolecular forces attributable to the characteristic molecular functionalities of the functional molecules, such as crown ether 36,37 and spirobenzopyran 38 derivatives, attached covalently on the probe tips.…”

Section: Introductionmentioning

confidence: 99%

Effect of Intramonolayer Hydrogen Bonding of Carboxyl Groups in Self-assembled Monolayers on a Single Force with Phenylurea on an AFM Probe Tip

2006

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IntroductionDuring the recent decade, atomic force microscopy (AFM) has attracted much attention as a promising analytical tool for precisely measuring intermolecular forces.1-5 AFM can be used to detect the force between its probe tip and substrate surfaces, even at the pN level. It is thus of great importance that there is almost no limitation of the environment and conditions where the AFM force measurements are carried out. Thus, if the AFM probe tip and the substrate are modified chemically with selfassembled monolayers (SAMs) 6,7 terminating with target functional groups, the intermolecular force in their molecular pairs can be evaluated by force-curve measurements in appropriate solvents by AFM. [8][9][10][11][12][13][14][15][16][17][18][19]36 Furthermore, the individual force for a variety of intermolecular forces at a single-molecule level can also be evaluated by statistical analyses of the forces obtained by repetitive adhesion force measurements. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]37,38 In our previous studies, we measured specific intermolecular forces attributable to the characteristic molecular functionalities of the functional molecules, such as crown ether 36,37 and spirobenzopyran 38 derivatives, attached covalently on the probe tips. These functionalized AFM probe tips, which possess a powerful capability of detecting supramolecular interactions, can be potentially utilized for developing a novel analytical tool for surface analysis based on force sensing by AFM.In such AFM force measurements, SAMs are often used for conveniently established covalent bonding of the target molecules onto the surfaces of the tip and substrate. Then, the intramonolayer interaction between the components in the SAMs can be expected to affect the force observed by the AFM technique. In other words, the AFM technique could detect such effects as the intramonolayer interaction on the interaction between the tip and the substrate. Intramonolayer hydrogen bonding is crucial in the SAMs of thiols or silanes bearing a terminal functional group, which can form hydrogen bondings between themselves. For example, terminal carboxyl groups in the SAMs of ω-carboxyalkanethiol can easily form hydrogen bonding within the monolayers. 39-42The COOH-terminated SAMs, such as thiol and silane, have been analyzed by FT-IR spectroscopy. 44 Especially, in the case of COOH-terminated SAMs, the effect of the intramonolayer hydrogen bonding between the neighboring carboxyl groups in the SAMs had been considered with respect to their surface property, such as wettability 45 and surface acidity (pKa) of the carboxyl groups. [41][42][43] In the present paper, we report an AFM force spectroscopic study concerning the effect of intramonolayer hydrogen bonding in COOH-terminated SAMs of 6-mercaptohexanoic acid (MHA) on the adhesion force observed between a SAM of MHA and a phenylurea derivative attached to the substrate and probe tip, respectively.Urea derivatives have a powerful ability to form hydrogen bondings, sin...

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Chemical bonds studied with functionalized atomic force microscopy tips

Cited by 127 publications

References 29 publications

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

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

Chemical force microscopy of chemical and biological interactions

Effect of Intramonolayer Hydrogen Bonding of Carboxyl Groups in Self-assembled Monolayers on a Single Force with Phenylurea on an AFM Probe Tip

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