Carboxymethyl dextran

Dextrans are also attractive as macromolecular carriers of paramagnetic chelates because of their hydrophilicity, the different available molecular weights with narrow polydispersity, and the versatility of activation methods applicable. Several DTPA- or DOTA-loaded carboxymethyl dextran (CMD) derivatives have been prepared and tested in blood pool MRI.136-139 The relaxivities reported for these compounds are, however, relatively moderate. 

The most successful technique has appeared to be the binding of antibodies to a matrix of carboxymethyl dextran macromolecules attached to... 

Figure 5. The binding of antibodies to carboxymethyl dextran matrix attached to a sensor surface.

SPR chips coated with a carboxymethyl dextran matrix are supplied commercially by Biacore, a leading manufacturer of SPR instruments. Similar technique can be used for preparation of carboxymethyl dextran matrix on Me(Si)Ox surfaces on which -OH groups are generated by reaction with 3-glycidoxypropyltrimethoxysilane13. 

Modified dextrans, such as carboxymethylated dextran were also coated onto glass slides to serve as matrix for protein immobilization and at the same time reduce non-specific binding22. 

The carboxymethyl-dextran derivative may be used to couple amine-containing molecules by the carbodiimide reaction. Heindel et al. (1994) prepared the lactone derivative of carboxymethyl-dextran by refluxing for 5 hours in toluene or other anhydrous solvents. The lactone derivative is highly reactive toward amine-containing molecules, thus creating a preactivated polymer for conjugation purposes. 

Carboxymethyl Dextran Medium Induced Medium Rigid Cyclic Side Chain Strong... 

Carboxymethyl Amylose Carboxymethyl Cellulose Carboxymethyl Dextran Carrageenan (A)... 

B. Johnsson, S. Lofas, G. Lindqurrst, A. Edstrom, R. M. Muller Hillgren, and A. Hansson, "Comparison of Methods for Immobilization to Carboxymethyl Dextran Sensor Surfaces by Analysis of the Specific Activity of Monoclonal Antibodies," Journal of Molecular Recognition JMR, 125-131 (1995). 

Surface immobilization of the capture molecules follows standard procedures that are commonly practiced in many biosensor applications and some are discussed in the previous section. Layers of carboxymethyl dextran. Protein A or Protein G, streptavidin-coated surface, or EDC [N-ethyl-N-(diethylaminopropyl) carbidimide]/NHS (N-hydroxysuccmimide)-based amine coupling through amide bond are used for protein (antibody, receptor, etc.) cross-linking. 

Also, if the substrate is completely covered by the hydrophilic hydrogel, like carboxymethyl dextran, crosscontamination and overflow during microdrop deposition may occur (18). 

Y. Zhou, O. Andersson, P. Lindberg and Liedberg, B. (2004) Protein microarrays on carboxymethylated dextran hydrogels immobilization, characterization and application. Microchim. Acta., 147, 21-30. 

A remarkable new method for the conversion of dextran and dextran derivatives, mainly towards mimetics of heparan sulfate uses comparable sulfation but applies 2-methyl-2-butene (2M2B) as an acid scavenger of neutral character [110]. This procedure shows a more efficient reaction combined with diminished chain degradation, as can be seen in Table 5. The method was used for the sulfation of carboxymethylated dextran. 

Table 13 Molecular weight and polydispersity of carboxymethyl dextran with different degrees of substitution (DS)...

The synthesis of CMDBSSu involves the random carboxymethylation of hydroxyl groups on the glucose units, the benzylamidation of some of the carboxylic groups with benzylamine in the presence of N-ethoxycarbonyl-2-ethoxy-l,2-dihydroquinoline (EEDQ) to carboxymethyl dextran benzylamide (CMDB), the sulfonation of phenyl rings and sulfation of remaining hydroxyl groups at the polymer backbone (Fig. 39, [108,222]). 

The synthesis steps described may also lead to carboxymethyl dextran sulfate (CMDSu) and carboxymethyl dextran benzylamide sulfate (CMDBSu, see Fig. 39). The anticoagulant activities depend on the proportion and distribution of the substituents. CMDBSSu represents a family of soluble... 

Fig. 39 Synthesis of carboxymethyl dextran sulfate (CMDSu), carboxymethyl dextran ben-zylamide sulfate (CMDBSu) and carboxymethyl dextran benzylamide sulfonate sulfate (CMDBSSu), respectively...

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