Surface modification acetylation

Here we show how to modify the piezoelectric surface to develop affinity sensors for detection of small molecular compounds using antibodies and (acetyl)cholinesterases (AChE), respectively. The chemical structures of the described surface modifications are shown in Fig. 

Ifuku, S., Nogi, M., Abe, K, Handa, K., Nakatsubo, F., Yano, H. Surface modification of bacterial cellulose nanofibers for property enhancement of optically transparent composites dependence on acetyl-group DS. Biomacromolecules 8, 1973-1978 (2007)... 

Based on the literature discussed in this chapter, it seems that surface modification of natural fibers is absolutely necessary to improve their thermal stability, dispersion in the polymer matrix, and compatibility with the polymer matrix. Physical and chemical methods reported have significantly modified the surface properties of the fibers as well as polymer matrices to improve the dispersion of the fibers and hence various properties of the polymers. Use of silane coupling agents and acetylation... 

Figure 9.2 Surface modification chemistries of nanocellulose for PLA/nanocellulose biocomposites, a, Acetylation b, Esterification with various organic acids c, d, e, Grafting of PCL, PLA, P(CL-fi-LA) f, Silanization g, Silylation h, Carbojymethylation combined with hexanoation i, PEG grafting j, Modified with polyhedral oligomeric silsesquioxane (POSS).

Interest in natural fibers obtained from different resources to reinforce polymer so as to get the novel composites is growing rapidly because they are renewable, cheap, recyclable, and biodegradable. Research in this field has prompted surface modification of natural fibers in order to improve the compatibility between hydrophilic fibers and hydrophobic matrix [1], Major challenges for polymer scientists in the development of structural natural fiber-reinforced composites are to increase the moisture resistance, dimensional stability with minimized matrix material, and to decrease the manufacture costs of the composite materials. Different researchers have used different surface modification methods, that is, mercerization [2], benzoylation [3], silanation [4], acetylation [5], graft... 

Surface modification of bacterial cellulose nanofibers by dependence on acetyl-group DS [159]... 

It was reported that the efiect of surface modification of flax on the ILSS of two-directional flax fabric/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites [121]. The ILSS values of the surface-treated flax fabric/PHBV biocomposites were greater than that of with untreated fabric. The plasma-treated specimen exhibited ILSS values greater than those for the acetylated one in comparison with the untreated specimens. The explanation for this was that aliphatic moieties with greater hydrophobicity may be formed on the fiber surfaces by ethylene plasma. It was noted that both acetylation and plasma treatment played an important role in improving the interfacial properties of flax/PHBV biocomposites, suggesting that the ethylene plasma treatment was more efiective. 

A true appreciation of the subtle and complex ways in which the nucleosome can influence gene expression, has come only recently, largely through studies of the post-translational modifications to which all histones are subject and of the enzymes that add and remove these modifications. It has been known for many years that the histone N-terminal tails are exposed on the surface of the nucleosome and that selected amino acid residues are subject to a variety of enzyme-catalyzed, post-translational modifications. These include acetylation of lysines, phosphorylation of serines, and methylation of lysines and arginines ([6,7], see also chapters by Davie, and Ausio and Abbott, this volume). The locations of the histone N-terminal tails in the nucleosome and the residues that can be modified are shown in Fig. 1. 

The first indication that modification of specific tail residues were linked to chromatin functional states, came from immunostaining of Drosophila polytene chromosomes with antibodies specific for H4 acetylated at defined lysines [13]. As shown in Fig. 2A, H4 acetylated at lysine 16 (H4acK16) was found almost exclusively on the transcriptional hyperactive male X chromosome (Fig. 2). (Genes on the Drosophila male X are transcribed twice as fast as their female counterparts so as to equalize levels of X-linked gene products between XY males and XX females.) In addition, H4 lysine 12 was found to remain acetylated in centric heterochromatin, while lysines 5, 8, and 16 were all under-acetylated [13]. These observations led to the suggestion that the histone N-terminal tails constitute nucleosome surface markers that can be recognized by non-histone proteins in a modification-dependent manner to alter the functional state of chromatin [13]. 

The major polymers that make up the wall are polysaccharides and lignin. These occur together with more minor but very important constituents such as protein and lipid. Water constitutes a major and very important material of young, primary walls (2). The lignin is transported in the form of its building units (these may be present as glucosides) and is polymerized within the wall. Those polysaccharides which make up the matrix of the wall (hemicelluloses and pectin material) are polymerized in the endomembrane system and are secreted in a preformed condition to the outside of the cell. Further modifications of the polysaccharides (such as acetylation) may occur within the wall after deposition. Cellulose is polymerized at the cell surface by a complex enzyme system transported to the plasma membrane (3). 

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