Crosslinking amidization

Isopeptide bond, inter-residue amide bonds between side chain functionalities such as covalent crosslinking amide bonds between the (w-amino group of diamino carboxylic acids such as lysine or ornithine and the (u-carboxyl function of amino di-carboxylic acids such as glutamate or aspartate. Isopeptide bonds occur, for example, in polymerized fibrin and in native wool. 

Crosslinked amides for beer United States 3,597,221 1971 Monsanto... 

Crosslinked amides in lami- United States 3,297,787 1967 Dow Chemical... 

Finally, a new water-soluble polyphosphazene was recently synthesized that has the structure shown in 36 (46). This polymer has two attributes as a biomedical macromolecule. First, the pendent carboxylic acid groups are potential sites for condensation reactions with amines, alcohols, phenols, or other carboxylic acid units to generate amide, ester, or anhydride links to polypeptides or bioactive small molecules. Second, polymer forms ionic crosslinks when brought into contact with di- or trivalent cations such as Ca or Ai3+. The crosslinking process converts the water-soluble polymer to a hydrogel, a process that can be reversed when the system... 

The structural versatility of pseudopoly (amino acids) can be increased further by considering dipeptides as monomeric starting materials as well. In this case polymerizations can be designed that involve one of the amino acid side chains and the C terminus, one of the amino acid side chains and the N terminus, or both of the amino acid side chains as reactive groups. The use of dipeptides as monomers in the manner described above results in the formation of copolymers in which amide bonds and nonamide linkages strictly alternate (Fig. 3). It is noteworthy that these polymers have both an amino function and a carboxylic acid function as pendant chains. This feature should facilitate the attachment of drug molecules or crosslinkers,... 

Perphosphate esters (e.g., methyl or ethyl esters) or amides can be used for oxidative gel breaking [1066]. Whereas the salts of the perphosphate ion interfere with the action of the crosslinkers, the esters and amides of perphosphate do not. Fracturing fluids that contain these breakers are useful for fracturing... 

Chromium(III) is a commonly-used crosslinker for preparing profile control gels with polymers having carboxylate and amide functionalities (la,b). Cr(III) is applied in many forms. For example, it can be used in the form of simple chromic salts of chloride and sulfate, or as complexed Cr(III) used in leather tanning (2), or as in situ generated Cr(III) from the redox reaction of dichromate and bisulfite or thiourea. The gelation rate and gel quality depend on which form of Cr(III) is used. 

There are reactive softeners, some of which are N-methylol derivatives of long-chain fatty amides (10.241) while others are triazinyl compounds (10.242). The N-methylol compounds require baking with a latent acid catalyst to effect reaction, whereas dichloro-triazines require mildly alkaline fixation conditions. The N-methylol compounds are sometimes useful for combination with crease-resist, durable-press, soil-release and water-repellent finishes. In this context, the feasibility of using silane monomers such as methyltri-ethoxysilane (10.243), vinyltriethoxysilane (10.244), vinyl triace tylsilane (10.245) and epoxypropyltrimethoxysilane (10.246) in crosslinking reactions to give crease-resist properties and softness simultaneously has been investigated [492]. 

Fraenkel-Conrat H, Olcott H. The reaction of formaldehyde with proteins. V. Crosslinking between amino and primary amide or guanidyl groups. J. Am. Chem. Soc. 1948 70 2673-2684. 

Philipp A, Meyer M, Zintchenko A, Wagner E (2011) Functional modification of amide-crosslinked oligoethylenimine for improved siRNA delivery. React Funct Polyrn 71 288-293... 

Figure 4.4 The reaction of DSP with amine-containing molecules yields amide bond crosslinks. The conjugates may be cleaved by reduction of the disulfide bond in the cross-bridge with DTT.

Figure 4.5 DTSSP can form crosslinks between two amine-containing molecules through amide linkages. The conjugates may be cleaved by disulfide reduction using DTT.

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