Mica surface, imaging

FIG. 23 SPFM image of a network of interconnected water channels formed after 5 seconds of tip contact at 40% RH, with a mica surface contaminated as a result of exposure to the ambient air for about 2 hours. Notice that many angles between segments are close to 120°. The area covered by the water structures increases with contact time. (From Ref. 51.)... 

Hellmann, J., Hamano, M., Karthaus, O., Ijiro, K., Shimomura, M. and Irie, M. (1998) Aggregation of dendrimers with a photochromic dithienylethene core group on the mica surface - atomic force microscopic imaging. Jpn. J. Appl. Phys., 37, L816-L819. 

Figure 15.5 AFM images of QoN -MePH clusters obtained from CeoN and MePH in THF-H2O (2 1) mixed solvent on a mica surface in the absence (a) and presence of magnetic processing at 8T (b) at 283 K.

Sample preparation for AFM analysis is relatively simple. Generally, a desired amount of sample is absorbed onto a smooth and clean substrate surface, for example, a freshly cleaved mica surface. For example, to prepare a food macromolecule sample for AFM imaging in air, the diluted macromolecule solution is disrupted by vortexing. Then, a small aliquot (tens of microliters) of vortexed solution is deposited onto a surface of freshly cleaved mica sheet by pipette. The mica surface is air dried before the AFM scan. A clean surrounding is required to avoid the interference of dust in the air. Molecular combing or fluid fixation may be applied to manipulate the molecule to get more information. 

Fig. 3.5 Representation of a scheme of an experiment (upper set of drawings) and the obtained experimental results presented as AFM images (middle part) and cross-sectional profiles (bottom) that provides evidence of silica nucleation and shell formation on biopolymer macromolecules. Scheme of experiment. This includes the following main steps. 1. Protection of the mica surface against silica precipitation. It was covered with a fatty (ara-chidic) acid monolayer transferred from a water substrate with the Langmuir-Blodgett technique. This made the mica surface hydrophobic because of the orientation of the acid molecules with their hydrocarbon chains pointing outwards. 2. Adsorption of carbohydrate macromolecules. Hydrophobically modified cationic hydroxyethylcellulose was adsorbed from an aqueous solution. Hydrocarbon chains of polysaccharide served as anchors to fix the biomacromolecules firmly onto the acid monolayer. 3. Surface treatment by silica precursor. The mica covered with an acid mono-...

Figure 5.25 AFM images of intermediate stmctures in self-assembly of peptide KFE8 in aqueous solution deposited on freshly cleaved mica surface (a) 8 min after preparation of solution. Inset electron micrograph of sample of peptide solution obtained using quick-freeze deep-etch technique (b) 35 min, (c) 2 h, and (d) 30 h after preparation. Reprinted with permission from Ref. 110. Copyright 2002 by the American Chemical Society.

Figure 12.3 Tapping mode AFM images of G4 PAMAM dendrimers on mica surface at different concentrations, (a) 0.1% w/w (b) 0.01% w/w (provided by Jing Li, D. A. Tomalia) [18]...

Figure 12.6 AFM images of a transferred film G2 (a) and G 3 (b) on freshly cleaved mica surface [24]...

Figure 12.11 Tapping Mode AFM image of G9 PAMAM dendrimer molecules on mica surface. Sample prepared by placing 6 jA of a dilute aqueous solution, cone. 5x 10-3% (w/w) G9 on a freshly cleaved mica surface and allowing the film to dry slowly at room temperature (provided by Jing Li and D. A. Tomalia)...

In the AFM images of Figure 12.15, one can see many separated and randomly deposited globular particles on the mica surface. In each image, the particles appear to be substantially uniform in size, i.e. they are essentially monodisperse. This is not surprising if each bright spot represents a single dendrimer molecule. 

Figure 12.21 Tapping mode AFM images of tecto-(dendrimer) molecules. (Sample preparation one drop of a 1 x 10 5wt% solution was spread on a freshly cleaved mica surface by spin coating, and then dried at room temperature)...

Figure 10.5 High resolution Atomic Force Microscopy image of plasmid DNA adsorbed on a cationic bilayer (DPTAP) coating a freshly cleaved mica surface. The highly packed DNA chains are clearly visible. The measured width of DNA is 2nm, close to the diameter of B-DNA (Adapted fromMou etal., 1995 Fang and Yang, 1997).

High resolution Atomic Force Microscopy image of plasmid DNA adsorbed on a cationic 178 bilayer (DPTAP) coating a freshly cleaved mica surface. The highly packed DNA chains... 

Fig. 54. a A typical image of closely packed pZT plasmid DNA molecules adsorbed onto a cationic lipid membrane of dipalmitoyldimethyl ammoniumylpropane. The image was recorded in 20 mMNaCl [513]. b Height image of tobacco mosaic viruses on the mica surface modified with bovine serum albumin (BSA). In contrast, direct adsorption from a solution containing BSA led to disperse adsorption of the TMV rods [517]... 

Fig. 34 SEM images of dextran ester nanoparticles (Table 9) from a sample 1, b sample 3, c sample 4, d sample 4 after 3 weeks storage in water, e sample 7, and f sample 8 (Table 9) on a mica surface...

Fig. 29 AFM images of PEI-retinoate particles dried on mica surfaces, (a) and (c) are top-view images of the PEI-600 retinoate and the PEI-750000 retinoate, respectively. The bird s-eye view (b) is a magnification of (a) enclosed in the plotted rectangle. Arrows in (b) indicate the depressions in the center of the particles, (d) is the top view of Poloxam-er 188 after the aqueous solution had been dried out. Reprinted with permission from [179]. Copyright 2000 American Chemical Society...

Figure 5 The orientated growth of AP25-35 fibrils from an aqueous solution on a mica surface. The fibrils grow along three main directions, each orientated at 120°. The images were collected by in situ time lapse Atomic Force Microscopy (Karsai, Grama et al. 2007). Copyright IOP Publishing Ltd. Reproduced with permission.

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