Immobilized monoclonal antibodies function

Electron Paramagnetic Resonance Spectroscopy Studies of Immobilized Monoclonal Antibody Structure and Function... 

CNTs can be functionalized with protein via non-covalent bond (Li et al., 2005 Kim et al., 2003 Mitchell et al., 2002). For example, (beta-lactamase I, that can be immobilized inside or outside CNTs, doesn t change enzyme s activity (Vinuesa and Goodnow, 2002). Taq enzyme can attach to the outside of CNT, and doesn t change its activity (Cui et al., 2004). Peptide with Histidine and Tryptophan can have selective affinity for CNT(Guo et al., 1998). Monoclonal antibody can attach to SWNTs. Protein-modified CNTs can be used to improve its biocompatibility and biomolecular recognition capabilities (Um et al., 2006). For example, CNTs functionalized with PEG and Triton X-100 can prevent nonspecific binding of protein and CNTs. Biotin moiety is attached to the PEG chains Streptavidin can bind specifically with biotin-CNT (Shim et al., 2002). 

This mode of separation, as the name suggests, uses stationary phases with a special affinity for a specific analyte. The affinity ligand immobilized on the stationary phase varies dramatically from peptide, to protein, to oligonucleotide, to monoclonal antibody. In some cases the target molecule is labelled with an affinity tag to simplify the separation. This approach is common in the synthesis of recombinant proteins where the system can be engineered so that the target biomolecule expresses a tag such as polyhistidine. A stationary phase functionalized with aminodiacetic acid and nickel chelate is then used to fish out the required molecule by chelating with the polyhistidine tag. 

As shown in Equation 1, the capacity per cycle is directly proportional to the amount of antibody immobilized, the immobilization yield, the M.W. of the protein and the column volume and an exponential function of the number of cycles. The amount of antibody immobilized will usually be less than 10 gL l. Higher activation of the matrix required for greater than 10 gL l loading results in a decrease in the immobilization yield. The maximum immobilization yield is 1.0 (100%) while 0.8 (80%) is not difficult to obtain. The M.W. of the protein to be isolated is fixed. The only way to increase the capacity per cycle significantly is to increase the volume of the immunosorbent or increase the number of cycles prior to reaching 50% of initial capacity (cycle half-life). Increasing the volume of immunosorbent increases the amount of monoclonal antibody required. 

A more selective extraction of MC from environmental samples or extracts from cyanobacteia can be achieved using lAC, with the use of sohd sorbents with immobilized anti-MC antibodies. For this purpose both polyclonal anti-MC-LR antibody can be used " exhibiting crossreactivity to other MC or also monoclonal antibodies. Antibodies are immobilized on various supports such as activated sihca gel, functionalized Sepharose, or less common ones such as Affi-Gel 10 or Formyl-Cellulofione. Some of these immunoaffinily sorbents are also commercially available. The preconcentration and clean-up... 

As with DNA above, a variety of proteins were immobilized non-covalently not only outside but also inside the CNT [138,150). Tsang et al. reported the first evidence for immobilization of small proteins inside MWNT by HRTEM [164-167], before DNA immobilization on the surface of MWNT as mentioned above [133,134]. After the innovative work by Sadler et aL, the cir-ciunference of CNTs was non-covalently functionalized with proteins directly or indirectly. MWNTs, prepared by arc discharge, were shown to be almost completely covered by streptavidin in helical arrangement [ 168]. SWNTs also adsorbed proteins and enzymes such as cytochrome c, ferritin, glucose oxidase and anti-fullerene IgG monoclonal antibody [169,170]. Indirect non-covalent functionaUzations of SWNTs with streptavidine and metallothionein were attained through triton-X 100-PEG-biotin and butylpyrene linkers, respectively [171,172]. 

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