Grafting of hydrophobic groups

There was no distinct difference between polymers having different molecular weights. From the data in Figures 2, 4, 5, and 6, it seems to be established that the affinity of polyanionic polymers for cell membrane is adjustable by a simple grafting of hydrophobic groups. 

Sunflower and wheat gluten proteins were successfully esterified by n-octanol. The grafting of hydrophobic groups to gluten and sunflower proteins decreased the solubility of die final inoduct obtained therefrom. 

Another method to improve the incorporation of bioactive polymers into the cells is the grafting of hydrophobic groups on the polymer, which improves the affinity for the cell membrane. Maleic copolymers are good candidates for such modifications, the anhydride cycle being easily reacted with hydrophobic amines. Poly(MA-St), poly(MA-CDA) and poly(maleic anhydride-alt-3,4-dihydroxyphenylprop-l-ene) modified with alkyl amines or aniline were proved to perturb the liposome membrane and to interact with epithelial cells or DMSO-differentiated HL-60 cells [48-50]. As a result, the biological activity, evaluated by the ability to simulate the release of superoxide anion by the cells, was enhanced when the polymer was modified with hydrophobic units [49]. 

Y. Suda, H. Yamamoto, M. Sumi, N. Oku, E Ito, S. Yamashita, T. Nadai, and R.M. Ottenbrite, Modified polyanionic polymers. 1 Grafting of hydrophobic group onto poly(maleic acid-alt-3,4-dihydroxyphenylprop-l-ene) to improve the affinity for cell membranes,/. Bioact Compat Pol, 7,15-24,1992. 

We modified polyanionic polymers by use of a grafting reaction of hydrophobic groups onto the polymers. After an extensive evaluation for the affinity of the hy-drophobically modified (hydrophobized) polymers to cell membrane, the immuno-stimulating activity of polymers was investigated by in vitro or ex vivo experiments. Consequently, the increased biological activity was found in the hydrophobized polymer, indicating that... 

The modification of water-soluble homopolymers by grafting a low amount of hydrophobic groups (of the order of 1 % of the monomers reacted is a typical figure), such as alkyl chains, leads to amphiphilic polymers which have a tendency to self-associate by hydrophobic interaction. This weak aggregation (Figure 20.8) leads to an increase in viscosity and in other rheological characteristics, and hence the use of these associative thickeners as rheology modifiers in paints and other products. 

Water-soluble polymers are modified by grafting a low amount of hydrophobic groups (of the order of 1% of the monomers reacted in a typical molecule), result-... 

Several block and graft copolymers have been shown to form stable aggregates under thermodynamically poor solvent conditions, as a result of differences in the solubility of different parts of a macromolecule. Whereas in a good solvent the experimentally measured value of A2 for a copolymer represents the balance of all the multiple interactions, under thermodynamically poor conditions A2 is mainly determined by the interaction of the groups situated on the polymer-solvent interface. Groups which form the hydrophobic core and are not in a contact with the solvent do not contribute significantly to the solution properties of the copolymer. 

Multihydroxyl containing monomeric or oligomeric p-cyclodextrins (PCD) such as those attained by grafting with glycidyl ethers of protected polyols (glycerol and pentitols) appeared rather promising components for their amphiphilic character, connected to the presence of an hydrophobic pocket and an external hydrophilic shell with an amplified number of hydroxyl groups. 

Short chain amphiphiles can be incorporated into the backbone of the polymer chains. The resulting graft macromolecules are able to form both intrachain and interchain aggregates. Polymeric surfactants assemble into a variety of intrachain micelles. These polymeric surfactants and/or amphiphilic polymacromonomers can also form mixed aggregates which incorporate free monomeric (macromonomer with a very small hydrophobic group) surfactants. 

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