Immobilization of ligands

Lofas L. and lohnsson B., A novel hydrogel matrix on gold surfaces in surface plasmon resonance sensors for fast and efficient covalent immobilization of ligands, J Chem Soc Chem Commun 1990, 1526. 

The reactions used for coupling affinity ligands to nanoparticles or microparticles basically are the same as those used for bioconjugation of molecules or for immobilization of ligands onto surfaces or chromatography supports. However, with particles, size can be a major factor in how a reaction is performed and in its resultant reaction kinetics. Since particle types can vary from the low nanometer diameter to the micron size, there are dramatic differences in how such particles behave in solution and how the density of reactive groups or functional groups affects reactions. 

Nillson, K., and Mosbach, K. (1984) Immobilization of ligands with organic sulfonyl chlorides. Meth. Enzymol. 104, 56-69. 

Fig. 7. Schematic representation of the non-covalent immobilization of ligands to a dendrimer support and the actual supramolecular dendritic complex containing 32 phosphine ligands 21).

Haloacetyl Method The haloacetyl method uses supports that contain lodoacetyl or bromoacetyl groups for the immobilization of ligands through sulfhydryl residues. These supports are usually prepared via the reaction of an amine-containing material with iodoacetic or bromoacetic acid in the presence of ethyldimethylaminopropyl carbodii-mide (EDC) at pH 4 to 5. EDC reacts with the carboxylic acid in iodo- or bromoacetic acid... 

Molecular conformation of bonded ligands and their degree of freedom is dependent on bonding density. The higher the bonding density, the lower the number of possible conformations and thus the less mobility the bonded chains have. Immobilization of ligands on the surface already restrict their mobility, so if we compare the state of free Cl 8 molecules (n-octadecyl) with immobilized octadecyl, we can expect more rigid (or solid-like) behavior of immobilized chain. Indeed, the study of the viscosity of bonded layers [64]... 

Dillmore, W. S., Yousaf, M. N., Mrksich, M. (2004). A photochemical method for patterning the immobilization of ligands and cells to self-assembled monolayms. Langmuir, 20, 7223-7231. 

Partitioning matrix The choice of matrix for the immobilization of ligand is dependent on the tag on the ligand (see Note 1). In our case, for the selection of aptamers against proteins, we find that His-tagged recombinant proteins are the best choice. Thus, we used Ni-NTA beads (Qiagen, Canada) as our matrix. 

Several approaches to immobilize transition metal catalysts on polymer supports have been reported in the literature. The most representative ones are (1) immobilization of ligands as well as ligand-metal complexes by covalent and/or coordination bonds (2) adsorption of catalysts on the supports (3) formation of ionic pairs between, for example, the surface of the support bearing anionic functional groups and cationic metal species and (4) entrapment of catalysts... 

In addition, as a hydrophilic and ftmctionalizable polymer, dextrans are used extensively for surface modification in biosensor fabrication. Dextran layers on sensor chips can effectively minimize nonspecific adsorption of analyte and facilitate surface immobilization of ligand, subsequently increasing the sensitivity of biosensors. 

Table 11 Commercially Available Preactivated Media for Immobilization of Ligands... 

Different Reaction Schemes to Attach Ligand Step 2 Immobilization of Ligand Coupling Agent Derivative... 

Fig. 8.6 Immobilization of ligands NH2HL2 and CH3H2L4 and generation of the Zn(II) complexes...

AC Biospecific High resolution Capture (-1-I-P) Specific binding Specific eluting Immobilization of ligand... 

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