Triggered cross-linking

Webb T, Matteucci M. Hybridization triggered cross-linking of deoxyoligo-nucleotides. Nucleic Acids Res 14 7661-7674, 1986. 

Examples of triggered cross-linked hydrogels. (a)Temperature, pH, and light-triggered sol-gel transition, (b) Polymeric chains with grafted antibodies are cross-linked in the presence of specific antigens, (c) Polymeric chains with immobilized RGD are cross-linked in the presence of cells. 

In the presence of the organic siHcate, the heavy-metal salts trigger the chain extension and cross-linking reactions that lead to siHcone mbber and volatile ethanol as a byproduct. Useful metal soaps iaclude stannous octanoate [1912-83-0], ziac octanoate [557-09-5], dibutyltin dilaurate [77-58-7], and dibutyltin diacetate [1067-33-0]. The reactivity of the different salts varies considerably. Stannous octanoate effects a cure ia 0.5—2 min ziac octanoate may require 24—96 h the dibutyltin dilaurate, 10—20 min. Heat and moisture accelerate the curing rate, but to a lesser degree than ia the case of the polysulfide mbbers. 

An allergen is usually an inert substance (e.g. pollen, house dust mite faeces) that in some individuals can trigger the generation of an (inappropriate) antigenic response. Mediated by TH2 lymphocytes, it causes B-Lymphocytes to produce lgE. Subsequent exposure of a sensitized individual to the allergen is therefore able to cross-link IgE antibodies on the surface of mast cells and trigger an immune response and histamine release. 

Fancy, D.A. and Kodadek, T., Chemistry for the analysis of protein-protein interactions Rapid and efficient cross-linking triggered by long wavelength light, Proc. Natl. Acad. Sci. USA, 96, 6020-6024, 1999. 

By far the most widely measured marker of hemostatic activation is D-dimer, which is a product formed by the action of plasmin on cross-linked fibrin (95). D-dimer levels in plasma are generally elevated in DIC. The consumption of platelets and coagulation proteins as a result of thrombin generation leads to the deposition of fibrin thrombi at multiple organ sites. This triggers fibrinolysis with an increase in the formation of fibrin degradation products, which can cause bleeding at multiple sites. Because DIC can have a variety of causes and may coexist with systemic fibrinolysis, such as in pulmonary embolism or deep vein thrombosis, the d-Dimer test is not specific for DIC (95). 

S. Mayor, K. G. Rothberg, and F. R. Maxfield. Sequestration of GPI-anchored proteins in caveolae triggered by cross-linking. Science 264 1948-1951 (1994). 

Hydrogels are 3D cross-linked polymer networks. They can withstand acid conditions and release the entrapped drug molecules. Purdue University researchers have used a poly[methacrylic acid-g-poly(ethylene glycol)] hydrogel to encapsulate insulin, which could be released by pH trigger. 

Active thrombin not only converts fibrinogen into fibrin, but also indirectly promotes its own synthesis by catalyzing the activation of factors V and Vlll. In addition, it catalyzes the activation of factor Xlll and thereby triggers the cross-linking of the fibrin. 

In the second stage, cross-link formation triggers phase separation, and further cross-link fixes the unevenly localized and deformed shape of particle. Thus, the red-cell-like particles are prepared during polymerization and not formed during isooctane evaporation. The red-cell-like particles find practically use for controlling rheological and optical characteristics in the coating and paint industry. 

Allergen cross-links IgE on mast cell (or basophil) and triggers degranulation and release of pharmacologic mediators... 

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