Carbodiimide method

The binding of antibody to latex particles was performed using the water-soluble carbodiimide (WSC) methodic) with l-ethyl-3-(3-dimethyl-aminopropyl) (EDAC Dojindo Laboratories, Kumamoto, Japan). In this method, carbodiimide activation of carboxylate groups on the surface of latex particles (under acidic conditions) produces an imstable reaction intermediate, O-acylisourea. O-acylisourea subsequently reacts with N-hydroxysuccinimide (NHS Acros Organics, Antwerp, Belgium) to produce a stable NHS ester (Fig. 1). 

Bisa2iridine compounds and A/-(2-chloroethyl)carbodiimides have also been prepared using isocyanide dichlorides and ethyleneimine (178,179). The iodide-cataly2ed rearrangement of the formerly mentioned compounds provides a method for preparing the tetrahydroimida2oimida2ole system ... 

RCO2H, R OH, DCC/DMAP, Et20, 25°, 1-24 h, 70-95% yield. This method is suitable for a large variety of hindered and unhindered acids and alcohols." Carbodiimide i was developed to make the urea by-product water soluble and thus easily washed out. ... 

Molecules of interest that contain free amino groups can be coupled in aqueous solution to /S-poIy(L-malate) as amides using carbodiimides such as the water-soluble l-ethyl-3(3-dimethyIaminopropyl)carbodiimide hydrochloride (EDC) [2,12,20,21]. By this method, the molecules are attached randomly. A selective amide bond formation at the carboxylate terminus can be achieved... 

The amount of resin used contains about 0.012 mole of active carbodiimide. Methods for preparing this reagent, determining its carbodiimide content, and regenerating spent resin are described in the preceeding procedure (p. 95). 

Carbodiimides have been prepared by desulfurization of thioureas by metal oxides, by sodium hypochlorite,4 or by ethyl chloroformate in the presence of a tertiary amine by halogena-tion of ureas or thioureas followed by dehydrohalogenation of the N,N -disubstituted carbamic chloride 8 and by dehydration of disubstituted ureas using -toluenesulfonyl chloride and pyridine.7 The method described above is a modification of that of Campbell and Verbanc. ... 

This method may be applied to the synthesis of a variety of aryl and alkyl carbodiimides. Other catalysts may also be used,10 but the especially active one described here is the one most easily obtained. The method is superior to other methods... 

Lee et al. reported a novel and simple method for delivery of adriamycin using self-aggregates of deoxycholic acid modified chitosan. Deoxycholic acid was covalently conjugated to chitosan via a carbodiimide-mediated reaction generating self-aggregated chitosan nanoparticles. Adriamycin was... 

The treatment of isocyanates with 3-methyl-l-ethyl-3-phosphoIene-l-oxide (59) is a useful method for the synthesis of carbodiimides in good yields. The mechanism does not simply involve the addition of one molecule of isocyanate to another, since the kinetics are first order in isocyanate and first order in catalyst. The following mechanism has been proposed (the catalyst is here represented as... 

Majetich and Hicks <96SL649> have reported on the epoxidation of isolated olefins (e.g., 61) using a combination of 30% aqueous hydrogen peroxide, a carbodiimide (e.g., DCC), and a mildly acidic or basic catalyst. This method works best in hydroxylic solvents and not at all in polar aprotic media. Type and ratios of reagents are substrate dependent, and steric demand about the alkene generally results in decreased yields. 

A useful method to synthesize ten and fourteen-membered ring imides 346 involved an initial condensation of macrocyclic -ketoestes 343 with alkyl or aryl isocyanates and carbodiimides, respectively, in the presence of a base [68]. After a nucleophilic attack of the enolate on the isocyanate C, the resultant amide N anion 344 induced a ring closure by addition to the keto group. Then, the intermediately formed four-membered ring 345 underwent a fragmentation... 

Reduction of uronic acids Uronic acids (UA) were converted to the corresponding neutral sugars (NS) by carbodiimide activation of the carboxyl groups followed by a reduction with NaBD4 according to the method of Kim and Carpita [5]. In order to achieve a complete reduction of the uronic acids the procedure was repeated once. 

Figure 15 Conjugation of a carboxylic add and an amine using the carbodiimide method. The carbodiimide activates the carboxyhc acid to speed up the reaction to the amine. Carbodiimides can be used with nonpolar or polar solvents, including water. Undesirable urea complexes may form as by-products. Details of the reaction are given in Table 3...

Like the carbodiimide method, the mixed anhydride method results in an amide complex (Table 5, Figure 17). The acid-containing hapten is dissolved in a dry, inert, dipolar, aprotic solvent such as p-dioxane, and isobutyl chloroformate is added with an amine catalyst. The activated mixed anhydride is chemically stable and can be isolated and characterized. The aqueous protein solution is added to the activated acid and the pH is maintained at around 8.5. A low temperature (around 10 °C) is necessary during the reaction to minimize side reactions. 

In aqueous solutions, the easiest method for forming this type of bond is to use the water-soluble carbodiimide EDC (Chapter 3, Section 1.1). For proteins and other water-soluble macromolecules, EDC reacts with their available carboxylate groups to form an intermediate, highly reactive, o-acylisourea. This active ester species may further react with nucleophiles such as a hydrazide to yield a stable imide product (Figure 1.109). 

Carbodiimide coupling to carboxylate-containing QDs usually involves the use of EDC in a single-step or two-step process to form an amide bond. If a one-step reaction is done, the QD is activated with EDC in the presence of an amine-containing molecule, such as a protein. Many protocols use this method, but it can result in protein polymerization in addition to coupling, because proteins contain both carboxylates and amines. A two-step protocol results in better control of the reaction (Figure 9.61). In the first step, EDC is used in the presence of sulfo-NHS to activate the carboxylates on the particles to intermediate sulfo-NHS esters. After a quick separation step to remove excess reactants, the activated QDs are added to the protein solution to be coupled. This then results in amide bond formation without polymerization of the protein in solution. See Chapter 3, Section 1 and Chapter 14, Section 1 for additional information on this process. 

These Ru(H)bpy32+ fluorescent silica nanoparticles were used to detect single bacterial cells using antibodies conjugated to the surface after functionalization with trimethoxysilyl-propyldiethylenetriamine followed by succinylation to create carboxylates. Specific antibody molecules against E. coli 0157 then were coupled to this modified fluorescent particle using the carbodiimide method with EDC and NHS (Zhao et al., 2004). 

Carboxylated silica particles may be coupled with amine-containing ligands, such as proteins, using a carbodiimide reaction with EDC. A similar protocol to that previously described for coupling to carboxylate polymer particles may be used. The following protocol is based on the method of Zhao et al. (2004), which was used for immobilizing monoclonal antibodies to E. coli 0157. 

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