Nanofibrillation

Coacervation occurs in tropoelastin solutions and is a precursor event in the assembly of elastin nanofibrils [42]. This phenomenon is thought to be mainly due to the interaction between hydro-phobic domains of tropoelastin. In scanning electron microscopy (SEM) picmres, nanofibril stmc-tures are visible in coacervate solutions of elastin-based peptides [37,43]. Indeed, Wright et al. [44] describe the self-association characteristics of multidomain proteins containing near-identical peptide repeat motifs. They suggest that this form of self-assembly occurs via specific intermolecular association, based on the repetition of identical or near-identical amino acid sequences. This specificity is consistent with the principle that ordered molecular assembhes are usually more stable than disordered ones, and with the idea that native-like interactions may be generally more favorable than nonnative ones in protein aggregates. 

B. Langlois. Fluid comprising cellulose nanofibrils and its use for oil mining. Patent WO 9802499, 1998. 

B. Langlois, G. Guerin, A. Senechal, R. Cantiani, I. Vincent, and J. Benchimol. Fluid comprising cellulose nanofibrils and its use for oil mining (fluide comprenant des nanofibrilles de cellulose et son application pour I exploitation de gisements petroliers). Patent EP 912653, 1999. 

Kaneko T, Higashi M, Matsusaki M et al (2005) Self-assembled soft nanofibrils of amphi-pathic polypeptides and their morphological transformation. Chem Mater 17 2484—2486... 

Ray S, Drew MGB, Das AK, Baneqee A. Supramolecular 8-sheet and nanofibril formation by self-assembling tripeptides containing an N-terminally located y-aminobutyric acid residue. Supramol Chem 2006 18 455-464. 

Hydrogenated nanofibrils were prepared by Fisher et al. (3) by reacting with LiAlH4 at 70°C for 2 hours. Massey et al. (4) postreacted these intermediates with -butyllithium and formed the corresponding lithiated fibrils, which were hydrolyzed to hydroxyls by reacting with air. 

Kajava, A. V., Potekhin, S. A., Corradin, G., and Leapman, R. D. (2004). Organization of designed nanofibrils assembled from alpha-helical peptides as determined by electron microscopy. / Pept. Sci. 10, 291-297. 

Keywords Bands Morphology Nanofibrils Poly(tetrafluorethylene) Single crystals Shish kebabs... 

Scanlon, S., Aggeli, A., Boden, N., Koopmans, R.J., Brydson, R., and Rayner, C.M., "Peptide aerogels comprising self-assembling nanofibrils". Micro Nano Lett. 2, 24-29 (2007). 

Abstract Cellulose is the most important biopolymer in Nature and is used in preparation of new compounds. Molecular structure of cellulose is a repeating unit of p-D-glucopyranose molecules forming a linear chain that can have a crystallographic or an amorphous form. Cellulose is insoluble in water, but can dissolve in ionic liquids. Hemicelluloses are the second most abundant polysaccharides in Nature, in which xylan is one of the major constituents of this polymer. There are several sources of cellulose and hemicelluloses, but the most important source is wood. Typical chemical modifications are esterifications and etherifications of hydroxyl groups. TEMPO-mediated oxidation is a good method to promote oxidation of primary hydroxyl groups to aldehyde and carboxylic acids, selectively. Modified cellulose can be used in the pharmaceutical industry as a metal adsorbent. It is used in the preparation of cellulosic fibers and biocomposites such as nanofibrils and as biofuels. 

Physical templates have also been used to facilitate the growth of PAn nanostructures. Nanofibril arrays were prepared by chemically depositing PAn into 20-200 nm pores in anodic aluminum oxide film (30-60 pm thick) that was subsequently etched away with 0.3 M H3P04or through ultrasonication.221... 

Fig. 2. SPM images of 10 x 10 pm area of lysozyme nanofibrils on surface of mica after immobilization period of 3 (a) and 8 (b) minutes. The height (h-scale) is 15 nm.

In Figure 1 we see bacterial cellulose that has been grown by Haigler in the presence of dissolved carboxymethyl cellulose (CMC), which inhibits the aggregation of the most elementary fibrils into the ribbons that are usually observed without the CMC. The most subelementary nanofibrils in Figure 1 are of the order of... 

Figure 1 Nanofibrils of cellulose from Acetobacterxylinum grown In the presence of CMC. Courtesy of Professor C. H. Haigler, In Biosynthesis and Biodegradation of Cellulose-, C. H. Halgler, P. J. Weimer, Eds. Marcel Dekker New York, 1991 p99.

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