Figure 11 Reaction of the activated carboxyl group of the protein with the amino groups on the inner surface of the capillary (From Ref. 3.)

Another successful way of attaching antibodies to capillaries has been to use capillaries modified with polyethylene glycol (PEG) linkers containing amine termini that can be coupled to the antibody glycan chains [43]. These capillaries have several advantages. Coupling the PEG to the glycan reduces the possibility of deactivating much of the antibody as occurs in passive adsorption, and the flexibility of the long PEG chain provides movement to the antibodies that increases the capture efficiency of the antibody. The PEG linker decreases nonspecific adsorption (NSA) of the Ab* to the capillary wall, and PEG added to the solution lowers NSA further, presumably by acting as a competitive inhibitor of interactions between the Ab* and the linker PEG [43].