Characterization of protein adsorption and immunosorption kinetics in photoablated polymer microchannels

A preliminary characterization of protein adsorption and immunosorption kin etics carried out in polymer microchannels is reported. A photoablated poly (ethylene terephthalate) (PET) surface and a PET/polyethylene sealing lamin ate were used for the channel microfabrication. The surface state of the PE T channel substrate and PET/polyethylene lamination were analyzed by using SEM and ATR-FTIR spectroscopy techniques. Protein adsorption and immunosorp tion studies were carried out using staphylococcal enterotoxin B (SEE) and polyclonal anti-SEE antibody (Ab) samples. Affinity purified polyclonal rab bit (Rb) anti-SEE Ab was radioiodinated and adsorbed in the microchannel. I t was determined that the maximum amount of adsorbed antibody was about 13. 0 pmol.cm(-2) (about 2 mug.cm(-2)), which corresponds to 0.81 pmol per micr ochannel. The distribution of the adsorbed protein on the walls of the micr ochannel depended on the surface state of the polymer exposed to the soluti on. The amount of the radiolabeled antibody adsorbed on the photoablated PE T was about 19.4 pmol.cm(-2), whereas it was only 5.5 pmol cm(-2) on the PE T/polyethylene lamination. About 30% of the anti-SEB Ab adsorbed on the mic rochannel surface was found to be biologically active. A study of the kinet ics of the SEE-anti-SEE Ab immunochemical reaction was also carried out. It could be substantiated that the forward reaction is diffusion controlled a nd that the equilibrium for such a reaction could be achieved within about 1 min in the microchannels. This is in good agreement with the calculation of a diffusion-controlled reaction in such a microchannel, according to Pic k's second law.