Influence of a poly-ethylene glycol spacer on antigen capture by immobilized antibodies

The use of spacers to distance an immobilized antibody from the surface of a support matrix introduces flexibility, which can reduce steric interferen ces between antibodies leading to a higher antigen capture efficiency. In t his paper we investigated the use of a spacer molecule, poly ethylene glyco l (PEG), between the matrix surface and antibodies for the capture of Bacil lus globigii, E. coli 0157:H7, and ovalbumin. The antigen capture efficienc y was determined using a surface ELISA method. Antibodies against the antig ens were covalently immobilized either directly or via PEG to glass surface s using a one-step EDC reaction. The amount of antibody immobilized was det ermined before blocking the nonspecific binding sites with bovine serum alb umin. Antibodies immobilized via a PEG spacer showed a higher capture effic iency compared to direct immobilization, which was more pronounced with lar ge antigens. Antibodies immobilized on glass supports were stable at 65 deg rees C for at least 80 min, and the capture efficiency increased with heati ng at 65 degrees C for 20 min. (C) 2000 Elsevier Science B.V. All rights re served.