Polymers carbohydrate-substituted

Fig.3A-D. Use of ring-opening polymerization (ROP) for neobiopolymer synthesis A General mechanism of cationic ROP. B Okada s use of cationic ROP to generate polymers with carbohydrate substituents at the terminus. C General mechanism for anionic ROP. D Okada s application of anionic ROP to generate carbohydrate-substituted polymers... 

Use of RuCI3 to Generate Carbohydrate-Substituted Polymers and Their Application to the Study of Multivalent Interactions... 

Fig. 5. Structure and biological activities of Kiessling s initial carbohydrate-substituted polymers generated by ROMP. Relative inhibitory potency the saccharide residue concentration needed to inhibit the agglutination of red blood cells mediated by the protein concana-valin A... 

Fig. 6. Comparison of the biological activities of monovalent glucose and mannose derivatives, multivalent carbohydrate-substituted polymer with two saccharide epitopes per repeat unit, and the less sterically congested carbohydrate-substituted polymer with a single recognition element per repeat unit. All polymers were generated by ROMP using RuC13...

In the case of first generation polymers, which display two saccharide epitopes for each monomer unit, the a-C-linked carbohydrate-substituted poly-... 

Use ofCI2(PR3)2RuCHCHCPh2 (R=Ph orCy) to Make Carbohydrate-Substituted Polymers... 

Fig. 8. First synthesis of carbohydrate-substituted polymers by ROMP using a defined orga-nometallic initiator. Grubbs synthesis of glucosamine-substituted polymers...

Fig. 9. Living polymerization to produce carbohydrate-substituted polymers by Schrock utilizing a defined molybdenum initiator...

Fig. 15. Mixed copolymers were generated to examine the effect of changing the recognition epitope density for a biologically active series of carbohydrate-substituted polymers. Note n and m represent ratios of mannose and galactose residues, respectively.

For the synthesis of carbohydrate-substituted block copolymers, it might be expected that the addition of acid to the polymerization reactions would result in a rate increase. Indeed, the ROMP of saccharide-modified monomers, when conducted in the presence of para-toluene sulfonic acid under emulsion conditions, successfully yielded block copolymers [52]. A key to the success of these reactions was the isolation of the initiated species, which resulted in its separation from the dissociated phosphine. The initiated ruthenium complex was isolated by starting the polymerization in acidic organic solution, from which the reactive species precipitated. The solvent was removed, and the reactive species was washed with additional degassed solvent. The polymerization was completed under emulsion conditions (in water and DTAB), and additional blocks were generated by the sequential addition of the different monomers. This method of polymerization was successful for both the mannose/galactose polymer and for the mannose polymer with the intervening diol sequence (Fig. 16A,B). 

As had been observed in the synthesis of carbohydrate-substituted polymers of different lengths, the reactivity of the monomers was an important parameter in generating the triblock polymers. If the mannose-substituted 7-oxanor-bornene derivative was first polymerized, followed by the galactose-derivatized norbornene and the mannose-substituted norbornene monomers, two distinct sets of products were observed. These were identified by modification of the resulting polymers by acetylation, and analysis of the products by GPC. With this protocol, it was found that the product was composed of short polymers (DP=... 

A disadvantage of traditional acrylamide polymerization reactions is the heterogeneity of the products that result. A radical polymerization method that produces polymers of similar structure but that are much more homogeneous is atom-transfer radical polymerization (ATRP) [155,156]. ATRP has been used to synthesize carbohydrate-substituted polymers with low polydispersities [157,158,159,160,161]. Materials that display sugar residues such as glu-cofuranose [160], glucopyranose [161], and A-acetyl-D-glucosamines [159]. 

It seems quite natural to ascribe the lesser polarisabxlities of the carboxyl group of the latter to a certain constitutional influence. They are derived from polymer carbohydrates and thus the presence of hydroxyl groups in the neighbourhood of the carboxyl group could be the cause of the decreased polarisability (cf. the well known action of hydroxyl substitution on the dissociation contants of fatty acids). 

C. Moreau, M. N. Belgacem, and A. Gandini, Recent catalytic advances in the chemistry of substituted furans from carbohydrates and in the ensuing polymers, Top. Catal, 27 (2004) 11-30. 

Synthesis of Polymers Substituted with Protected Carbohydrate Residues... 

The interest in using saccharide-substituted polymers to bind and cluster cell surface proteins arises from studies of L-selectin, a protein involved in inflammation. L-selectin binds glycoproteins that display complex carbohydrates, and... 

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