Protein recognition nonspecific

When the gold tip is functionalized with alkanethiols terminated with nitrilotriacetate (NTA) group, recombinant histidine-tagged proteins can attach to it via their carboxy or amino group. This method allows the optimal exposure of the C-terminal or N-terminal domains. Moreover, it can orient the attached molecules in the same way and minimize nonspecific protein adsorption and allows low density coupling to ensure single molecule recognition. But... 

It is hypothesized that nonordered protein adsorption on materials begins the cascade leading to the foreign body reaction, since all normal biological events operate on a system based on specific recognition of proteins and polysaccharides [62,63]. To control nonspecific adsorption, several surface modification approaches have been explored stealth materials are designed to decrease nonspecific protein adsorption while others promote adsorption of specific proteins in an effort to direct biological processes [63,64]. 

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). 

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