Force-distance curves by atomic force microscopy

Cappella, Brunero; Dietler, Giovanni

doi:10.1016/s0167-5729(99)00003-5

Cited by 1,484 publications

(1,080 citation statements)

References 224 publications

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“…With the SFA, the interaction forces are measured between two curved mica plates in the crossed-cylinder geometry. 2,14,15 The colloidal probe technique, which is based on an atomic force microscope (AFM), uses a colloidal particle of a few micrometers, attached to the end of the cantilever to probe the interaction force with a planar substrate (sphere-plane geometry) 10,[15][16][17][18][19][20][21] or with a second colloidal particle mounted to the substrate (sphere-sphere geometry). [22][23][24][25][26] While any of these techniques could be used to assess the validity of the Derjaguin approximation, to the best of our knowledge there is only one study addressing this question.…”

Section: Introductionmentioning

confidence: 99%

Probing the validity of the Derjaguin approximation for heterogeneous colloidal particles

Rentsch

Pericet-Cámara

Papastavrou

et al. 2006

Phys. Chem. Chem. Phys.

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The Derjaguin approximation states that the interaction force between two curved surfaces is proportional to their effective radius, whereby the inverse effective radius is the arithmetic mean of the inverse curvature radii of the surfaces involved. The present study investigates the validity of this approximation with an atomic force microscope (AFM) by measuring interaction forces between colloidal particles of different sizes, but of identical composition. Forces were measured between silica particles of 2.0, 4.8 and 6.8 mm in diameter in KCl electrolyte solution with and without adsorbed poly(amido amine) (PAMAM) dendrimers. The Derjaguin approximation could be confirmed at all distances investigated, including those comparable with the characteristic length scales of the surface roughness or the surface charge heterogeneities. For the conditions investigated, the Derjaguin approximation turns out to be surprisingly robust.

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Section: Introductionmentioning

confidence: 99%

Probing the validity of the Derjaguin approximation for heterogeneous colloidal particles

Rentsch

Pericet-Cámara

Papastavrou

et al. 2006

Phys. Chem. Chem. Phys.

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“…The curves were also acquired in ambient conditions, at several points over the sample scanned area. The theoretical background and possible applications of AFS are given in the reviews (Cappella and Dietler, 1999;. The small angle X-ray scattering (SAXS) experiments were conducted at the National Synchrotron Light Laboratory (LNLS), Campinas, Brazil, using a monochromatic X-ray beam (l = 1.488 Å ).…”

Section: Methodsmentioning

confidence: 99%

Doping in poly(o-ethoxyaniline) nanostructured films studied with atomic force spectroscopy (AFS)

Leite¹,

Alves²,

Neto³

et al. 2008

Micron

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“…The force exerted between the tip and the sample surface are a combination of attractive van der Waals (vdW) forces and long range Coulomb forces (Cappella and Dietler, 1999). VdW forces include forces between permanent dipoles (Keesom forces), forces between induced dipoles and permanent dipoles (Debye forces) and dispersion forces or forces between induced dipoles (London forces).…”

Section: Colloidal Probe Afmmentioning

confidence: 99%

“…Their magnitude depends both on the intermediate medium and on the geometry of the bodies in contact. Snap-in occurs when the attractive vdW forces are large enough to overcome any repulsive forces and the cantilever elastic constant (Cappella and Dietler, 1999).…”

Section: Colloidal Probe Afmmentioning

confidence: 99%

Characterisation of dry powder inhaler formulations using atomic force microscopy

Weiss

McLoughlin

Cathcart

2015

International Journal of Pharmaceutics

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A B S T R A C TInhalation formulations are a popular way of treating the symptoms of respiratory diseases. The active pharmaceutical ingredient (API) is delivered directly to the site of action within the deep lung using an inhalation device such as the dry powder inhaler (DPI).The performance of the formulation and the efficiency of the treatment depend on a number of factors including the forces acting between the components. In DPI formulations these forces are dominated by interparticulate interactions. Research has shown that adhesive and cohesive forces depend on a number of particulate properties such as size, surface roughness, crystallinity, surface energetics and combinations of these. With traditional methods the impact of particulate properties on interparticulate forces could be evaluated by examining the bulk properties. Atomic force microscopy (AFM), however, enables the determination of local surface characteristics and the direct measurement of interparticulate forces using the colloidal probe technique. AFM is considered extremely useful for evaluating the surface topography of a substrate (an API or carrier particle) and even allows the identification of crystal faces, defects and polymorphs from high-resolution images. Additionally, information is given about local mechanical properties of the particles and changes in surface composition and energetics. The assessment of attractive forces between two bodies is possible by using colloidal probe AFM.This review article summarises the application of AFM in DPI formulations while specifically focussing on the colloidal probe technique and the evaluation of interparticulate forces.2015 Elsevier B.V. All rights reserved.

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Force-distance curves by atomic force microscopy

Cited by 1,484 publications

References 224 publications

Probing the validity of the Derjaguin approximation for heterogeneous colloidal particles

Probing the validity of the Derjaguin approximation for heterogeneous colloidal particles

Doping in poly(o-ethoxyaniline) nanostructured films studied with atomic force spectroscopy (AFS)

Characterisation of dry powder inhaler formulations using atomic force microscopy

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