Imaging of individual biopolymers and supramolecular assemblies using noncontact atomic force microscopy

Supramolecular Structure and Renaturation of a (1→3)-β-d-Glucan Compared with Curdlan and Scleroglucan

“…The diameter of the strands for curdlan was about 1.6 nm, slightly larger than that reported for the triple strand thickness by X-ray fiber diffraction, 1.56 nm [8,26]. Moreover, this discrepancy between values by AFM and those determined by other techniques has already observed by other authors, and they propose that the dissimilarity might result from the fact that the molecules were distorted by desiccation or by interaction with the mica substrate, or that the molecules were partially embedded in a layer of water adhering to the mica surface [27]. The diameter of the strands of the (1→3)(1→2)-β-D-Glucan was about 1.8 nm [20], similar to that found in the literature for scleroglucan [28].…”

Diatom Polysaccharides: Extracellular Production, Isolation and Molecular Characterization

“…Polysaccharide samples for AFM imaging [69][70][71][72] and polysaccharide gels [70,[73][74][75][76][77] are usually spread on freshly cleaved mica surface. The imaging of hydrated samples is preferably conducted in air to inhibit the unfavourable motion of polysaccharides in liquid medium.…”

Food Nanotechnology

“…The tapping mode of AFM can be used for structural investigation of delicate biopolymer structures, such as hylan (Cowman et al, 2000) or xanthan gum (Camesano and Wilkinson, 2001). The noncontact mode is also very useful in imaging isolated biomacromolecules or supramolecular assemblies, since it is able to avoid sample disruption or tip contamination; several non-contact studies have been performed on food biomacromolecules such as xanthan gum, k-carageenan, gellan, and collagen (McIntire and Brant, 1997).…”

“…Investigation of food biopolymer properties using the tools of nanotechnology III.B.1. Molecular structure AFM has been increasingly used in the last decade for the structural characterization of food biopolymers such as starch (Gallant et al, 1997;Baker et al, 2001), hydrocolloids (Baker et al, 1997;McIntire andBrant, 1997), andproteins (McMaster et al, 1999 -gliadin molecules). AFM images of zein film drop, deposited onto a silicon wafer with a hydrophobic coating, helped Panchapakesan (2005) visualize the orientation of zein molecules on the surface of the film (Figure 21.5).…”