Atomic force microscopy nanostructure size

C. Robinson, K. Yamamoto, S.D. Connell, J. Kirkham, H. Nakagaki, A.D. Smith, The effect of fluoride on the nanostructure and surface pK of enamel crystals An atomic force microscopy study of human and rat enamel, Eur. J. Oral Sci. 114 (2006) 99-104. E.D. Eanes, A.W. Mailer, The effect of fluoride on the size and morphology of apatite crystals grown from physiological solutions, Calcif. Tissue Int. 63 (1998) 250-257. 

X-ray diffraction technique is a non-destructive analytical technique that reveals information about crystallographic structure, chemical composition and physical properties of nanostructured materials. UV/Vis spectroscopy is routinely used in the quantitative determination of films of nanostructured metal oxides. The size, shape (nanocomb and nanorods etc,) and arrangement of the nanoparticles can be observed through transmission electron microscope (TEM) studies. Surface morphology of nanostructured metal oxides can be observed in atomic force microscopy (AFM) and scanning electron microscopy (SEM) studies. 

Atomic force microscopy (AFM) was first applied to investigate the polymer surfaces in 1988 shortly after its invention [23]. Today, studies by AFM range from simple visualization of morphology to more advanced examination of polymer structure and properties at the nanometer scale. AFM gives three-dimensional pictures of the surfaces, while other methods, SEM and TEM, do not. AFM is frequently applied to polymer surfaces, principally to reveal morphology, nanostructure, chain packing, conformation, pore size, and pore size distribution at the surface. 

Microscopy techniques may also be used to perform size estimations and to corroborate the size homogeneity in a population. Transmission electronic microscopy (TEM), scanning electronic microscopy (SEM) and atomic force microscopy (AFM) are the most used. Nevertheless, these techniques are more often applied for visual characterization of size and distribution in order to corroborate data obtained with other techniques. This is because the theory behind most of the techniques used for size determination relies on the use of monodisperse and spherical particles. Any deviation from this condition may give unrealistic results that consequently may affect the efficacy of the system. In TEM measurements, a contrast agent is normally necessary for proper visualization, such as uranyl acetate, osmium tetroxide, ammonium molybdate or phosphotungstic acid. Because of its high resolution, AFM can also be useful to detect interactions between plasmids and nanostructures [77]. 

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