Thiol functionalized cross linker

There are several methods available for preparing surface functionalized metallic colloids for use as biological labels. The three most widely used fabrication methods include non-covalent absorption of biomolecules to the particle su face binding to the metal surface via a thiol functionalized cross linker, and covalent binding to a derivatized silica or polystyrene shell that encompasses the metal particle . 

Specific groups involved in covalent immobilization of biomolecules to the surface are very often introduced into the structure of this molecule, especially in oligonucleotides and carbohydrates. Carboxylic and amino functionalities are the modifications most frequently used, although aldehyde, thiol, and oxyamino are useful alternatives. In some cases coupling molecules (cross-linkers) are necessary to increase the affinity (or reactivity) of the interacting groups. 

Heterobifunctional cross-linkers are employed to couple two different functional groups between the monolayer and the molecule for the subsequent immobilization. The wide range of these cross-linkers and their specific reactions are presented in Figure 14.7. One example in which the use of heterobifunctional cross-linkers was applied for immobilization of biomolecules was the work of Com and coworkers where the sulfosuccinimidyl 4-(fV-maleimidomethyl)cyclohexane-l-carboxylate (SSMCC) linker was applied to link thiol-modified DNA molecules with an amino-functionalized surface.54... 

As a class, the cross-linkers used to attach thiol-modified oligonucleotides to solid supports are hetero-bifunctional, meaning that they possess functional groups capable of reaction with two chemically distinct functional groups, e.g., amines and thiols. Hetero-bifunctional cross-linkers can covalently bind two distinct chemical entities that would otherwise remain unre-active towards each other [8]. 

Di- and tri-functional thiol (or mercapto) molecules are used as cross-linkers for halogen-containing polymers. Like the bisphenols, they may require an accelerator, depending on the inherent reactivity of the halogen cure site and the particular... 

The development of several degradable hydrogels utilizing ATRP technique has also been reported they include preparation of acidic pH-responsive hydrogels based on thermoresponsive poly(N-isopropylacrylamide-co-5,6-methylene-1,3-di-oxepane) [174], redox-responsive hydrogels based on thiol/disulfide-functional-ized star polymers [175] and radical-responsive gels based on a dynamic covalent trithiocarbonate cross-linkers [176]. 

For example, polymerizing inorganic nanoparticles with cross-linker divinyl-benzene yields composite polymer-inorganic latex particles functionalized with vinyl groups. In the process of composite miniemulsion polymerization, vinyl groups were easily introduced to the particle surface by using cross-linker divinylbenzene, thiol-terminated polymers can be further clicked on the particle surface via a thiol-ene approach catalyzed by V-50 as a free-radical source (Figure 8.27) [48]. 

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