Electron microscopy micelles

Association and shattering of micelles. Electron microscopy shows that the casein micelles aggregate initially, then disintegrate and finally aggregate into a three-dimensional network. 

Peculiar DNA architecture was demonstrated in 25% aqueous ethanol when DNA was complexed with series of cationic detergents in the presence of poly(glutamic acid) [124]. Electron microscopy and x-ray scattering demonstrated that DNA can pack cetyltrimethylammonium bromide molecules into rodlike micelles, which form a hexagonal lattice. Interestingly, circular dichroism spectroscopy revealed that in these complexes DNA adopts left-handed conformation. 

Dalgleish, D. G., Spagnuolo, P. A., and Douglas Goff, H. (2004). A possible structure of the casein micelle based on high-resolution field emission scanning electron microscopy. Int. Dairy. 14,1025-1031. 

McMahon, D. J. and McManus, W. R. (1998). Rethinking casein micelle structure using electron microscopy. /. Dairy Sci. 81,2985-2993. 

Colloidal dispersion 1.0 nm-1.0 pm Particles not resolved by ordinary microscope but visible by electron microscopy pass through filter paper but not semipermeable membranes generally slow diffusion Colloidal silver sols, surfactant micelles in an aqueous phase, aqueous latices and pseudolatices... 

Scanning electron microscopy (SEM) techniques have proven to be suitable for the visualization of block copolymer micelles, as illustrated in, e.g., the recent work of Erhardt et al. on Janus micelles (Sect. 7.3) [55]. 

Portnaya, I., Cogan, U., Livney, Y.D., Ramon, O., Shimoni, K., Rosenberg, M., Danino, D. (2006). Micellization of bovine p-casein studied by isothermal titration microcalorimetry and cryogenic transmission electron microscopy. Journal of Agricultural and Food Chemistry, 54, 5555-5561. 

Marchin, S., Putaux, J.L., Pignon, F., Leonil, J. (2007). Effects of the environmental factors on the casein micelle structure studied by cryo-transmission electron microscopy and small-angle X-ray scattering/ultra-small-angle X-ray scattering. Journal of Chemical Physics, 126, 45-101. 

Martin, A., Goff, H.D., Smith, A., Dalgleish, D.G. (2006). Immobilization of casein micelles for probing their structure and interactions with polysaccharides using scanning electron microscopy (SEM). Food Hydrocolloids, 20, 817-824. 

Electron microscopy shows that the interior of the micelles are not uniformly electron dense. 

Transmission electron microscopy (TEM) has been used to provide a direct image of block copolymer micelles that complements the indirect information obtained from scattering experiments. Because of the technical difficulties of obtaining electron micrographs from solutions it is not employed routinely. Price and co-workers (Booth et al. 1978 Price and Woods 1973) obtained specimens for TEM investigation by two methods. In the first (Price and Woods 1973),... 

Figure 12 Transmission electron microscopy study of protein desorption in icecream mix containing emulsifiers and hydrocolloids, (a) Immediately after homogenization the fat globules (0 are stabilized by adsorbed partially dissociated casein micelles (arrows), (b) During ageing the mix at 5°C, the previously adsorbed protein film is released in the form of coherent protein layers (arrows) into the water phase (w). (c) After mechanical treatment in the ice cream freezer, desorbed protein layers are seen more often in the water phase without association to fat giobules (arrows). From reference 48, courtesy of Dr. W.Buchheim, Kiel, Germany.

Monoglycerides and mono-diglycerides have low HLB values and cannot form micelles. They build up a multi-layer at the surface, resulting in a constantly decreasing surface tension as their concentration increases. However, in systems with proteins such as fat-free ice cream mixes, these emulsifiers behave as if they have a CMC. A possible explanation for this observation is that the unbound emulsifier in the fat-free mix is in equilibrium with the protein-bound emulsifier. Above a certain concentration of emulsifier in the mix, any surplus of emulsifier will adhere to the protein in the water phase after the surface has been saturated. The unadsorbed emulsifier is seen as very small crystals less than 200 nm by electron microscopy analysis4. ... 

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