Amphiphilic linker

Figure 3.9 Solubilisation improvement of a conventional surfactant (a) by a lipophilic linker (b), an amphiphilic linker (c), or an extended surfactant (d).

Another improvement of the solubilisation has been accomplished by adding short amphiphilic block copolymers in low concentration (see Section 4.2 for details). Briefly, these polymers have a polyethylene-propylene hydrophobic block and a polyethylene oxide head group and are thus similar to the ethoxylated non-ionic surfactants to which these are added. The main difference is that the two blocks of the amphiphilic polymer are several times larger than the corresponding low molecular weight surfactant. The role of these polymers is to increase the reach of the amphiphilic layer such that it extends deeper into both the oil and the aqueous phase in accordance with Winsor s premise. As a consequence, they are found to notably increase solubilisation [50]. As seen in Fig. 3.9(c), these additives could be called amphiphilic linkers since they act upon both sides of the interface. 

Fig. 8. De novo designed a-hehcal proteins. Dimers of the amphiphilic helix-forming peptide a B, GELEELLKKLKELLKG (see Table 1), in which the nature of the linker connecting the individual heflces plays a critical role in the stmcture of the final protein, (a) Using a Pro residue as the linker, ie, a B-Pro-a B, three molecules aggregated to form a trimeric coded-cod. (b) Using Pro-Arg-Arg as the linker, ie, a B-Pro-Aig-Arg-a, resulted in the...

Figure 7. SEM and XRMA microphotographs of palladium catalysts supported on the amphiphilic resin made by DMAA, MTEA, MBAA (cross-linker) [30]. Microphotographs (a) and (b) show an image and the radial palladium distribution after uptake of [Pd(OAc)2] from water/acetone the precursor diffuses only into the outer layer of the relatively little swollen CFP after reduction the nanoclusters remain close to the edge of the catalyst beads. Microphotographs (c) and (d) show the radial distribution of sulfur and palladium, respectively, after uptake of [PdCU] from water after reduction palladium is homogenously distributed throughout the catalyst particles. This indicates that under these conditions the CFP was swollen enough to allow the metal precursor to readily penetrate the whole of polymeric mass. (Reprinted from Ref. [30], 2005, with permission from Elsevier.)...

The same group modified the linker by using different numbers of carbon atoms (1, 5, 10) to afford variations of the local saccharide concentrations at the dendrimer surface.418 This study was aimed to determine the influence of this linker parameter on the glycodendrimer-protein interactions, the relationship between structure and water solubility, and to investigate amphiphilic properties. 

In a series of papers, Kennedy and co-workers studied the amphiphilic networks and their membrane characteristics. The use of poly(pentamethyl)cyclopentasiloxane)32 as an oxyphilic cross-linker in the novel tricontinuous membranes, consisting of hydrophilic and lipophilic polymers, was reported.466 The presence of polysiloxane brought about high oxygen permeability, which was studied in the water-swollen membranes.467 The use of polysiloxanes as sorbents,468 and as carriers for the receptor molecules in the ion-exchange membranes,469 470 was reviewed. 

Gohy JE, Lohmeijer BGG, Alexeev A, Wang XS, Manners 1, Winnik MA, Schubert US (2004) Cylindrical micelles from the aqueous self-assembly of an amphiphilic poly(ethylene oxide)-b-poly(ferrocenylsilane) (PEO-b-PES) block copolymer with a metallo-supramolecular linker at the block junction. Chem Eur J 20 4315 323... 

The linker group that bridges the cationic lipid headgroup with the hydrocarbon moiety controls the biodegradability of a cationic amphiphile. Most of the linker bonds are ether, ester, or amide bonds (Fig. 1). Compounds with ether links generally render better transfection efficiency. However, they are more stable and may cause higher toxicity, while cationic lipids with ester links such as DOTAP are more biodegradable and less cytotoxic in cultured cells [28, 39]. Noteworthy,... 

Choosing a block-copolymer with both hydrophilic and hydrophobic domains as the amphiphilic substance, the appHcation of suitable linking methods can lead to the formation of an irreversibly closed capsule around every single nanotube. The reaction with a diamine linker may for instance initiate a crosslinking in the polyacryhc acid domains of an amphiphilic polystyrene/polyacrylic acid copolymer. Upon addition of water to a solution in DMF the latter form micelles with the nanotubes in the center. Contrary to the simple micelles mentioned in the previous paragraph, the crossHnked species can be dried and redispersed. 

The overall synthesis of both PCL cross-linkers and poly[2-(N,N-dimethylamino)ethyl methaciylate-/mA eJ-poly(8-caprolactone)] model amphiphilic conetworks PDMAEMA-/-PCL have been already reported in a separate contribution with all experimental conditions described in details (33). 

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