Spacer polymeric

The important advantage of the immunosorbents based on WPG-PA is the fast rate of biospecific interaction between the oligosaccharides and antibodies. For B-trisaccharide-WPG-PA the average sorption time of monoclonal B8 antibodies was 20 times shorter than with B-trisaccharide-Sepharose 4B. The role of the flexible polymeric spacer, therefore, is in this case very pronounced. 

Another kind of contact-active antimicrobial surface was achieved by tethering antimicrobial peptides to surfaces [62], If such peptides were exclusively membrane-active they could not work like in solution but would be immobilized via a polymeric spacer that could potentially cross the cell wall. The latter was demonstrated by the group of Dathe, who immobilized cationic antimicrobial peptides on PentaGels [63], Also, the well-known antimicrobial peptide magainin I... 

Figure 19.19 Left side Variation of the photoluminescence intensity E (b) of the PEG-functionalized Au and CdTe nanoparticles depending on the temperature (a) (c) shows the calculated photon-field enhancement factor P of the CdTe nanoparticles as a function of time. Right side Schematic representation of a dynamic nanothermometer based on a nanoparticle superstructure. This superstructure consists of two types of nanoparticles (gold and CdTe) connected by polymeric spacers.118 (Reprinted with permission from J. Lee et al., Angew. Chem. Int. Ed., 2005, 44, 7439-7442. Copyright Wiley-VCH Verlag GmbH Co. KGaA.)...

The monomeric unit used in the studies in shown in Fig. 45.3. It is based on poly(s-caprolactone) with a terpyridine ligand (for metal complexation) at one end and an ureido-pyrimidone group (for hydrogen bonding) on the other end. The polymeric spacer is used to control the solubility in various solvents, in such a way that both hydrogen-bonding and metal-complexation can take place simultaneously. This unit shows a good solubility in chloroform. 

These polymers show interesting photophysical and electrochemical properties, thereby making them of potential interest for use in devices with solar cells and light emitting diodes. With the variation of the length and type of polymeric spacers, these properties can be modified to have tailored properties. 

In a similar general approach, Namazi and Adeli reported thermore-versible hydrogels formed from ABA-type copolymers. The A blocks were constituted from dendritic citric acid and the B block was a polyethylene glycol unit (Fig. 10) [47]. This dendrimer has a dumb-bell-type structure, somewhat reminiscent of Newkome s bola-amphiphiles, only with a polymeric spacer chain. First- and second-generation dendritic systems were reported and it was found that the gels could also be formed in the presence... 

In addition, chemical functionalization allows one to implement oligomeric or polymeric spacers that have proven beneficial to ensure that the rupture of a supramolecular bond takes place when the two surfaces are physically well separated. In the case of force hysteresis attributed to the rupture of the tip-substrate contact, that is, the sometimes strong detachment force between the tip and the solid surface, a longer polymer chain ensures that the targeted single-molecule rupture force is not hidden in the hysteresis part of the f-d curve. Furthermore, the rupture of the supramolecular bond is not affected by the presence of the surface and possible long-range surface forces. ... 

The tip and substrate remain linked because of the specific recognition between the complex pair and the polymeric spacer is farther stretched (Figure 1, step 4), resulting in the bending of the cantilever toward the subsfrate. When the polymer spacer is stretched further, the weakest link along the molecular tip-sample bridge ruptures. 

The previous maximally bent cantilever quickly relaxes to the nonbent state because of the absence of force. Correspondingly, a sudden drop in the force curve is noticed, which is attributed to the rupture of the specific bond between a pair of molecules. Regions 3 and 4 reflect the elasticity of the polymeric spacer, which can... 

Fitting of the curve to models of polymer elasticity. For a single-molecule experiment with a polymeric spacer, the elastic behavior can be simnlated by or fitted to the theoretical models discussed above. Nevertheless, as mentioned above, sometimes the fitting also fails in describing the elastic properties of the molecnles. 

Polymeric spacer with multiple ligand attachment. 

A third alternative is offered by polymeric spacers. These can be prepared by a wide variety of methods. Examples are dextran-coated beads [54] or polyvinyl-... 

The word Tegular in the heading is used here to mean ordinary , or, in the case of copolymers, random or statistical types with no special attributes such as non-polymeric spacer groups (called junction units by lUPAC). As mentioned above, these are drawn usually as either structure-based, i.e., -(-A-)n-, or source-based, i.e., (A B- -jjt. 

This section discusses structure-based and source-based nomenclature for ordered, segmented, and unordered block polymers, and polymers with non-polymeric spacer units or junction units . Star-block polymers are discussed under star polymers. 

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