Characterization of IgG Langmuir-Blodgett films immobilized on functionalized polymers

The bioactivity of anti-human IgG Langmuir-Blodgett (LB) films, the non-spe cific adsorption of protein and the topography of anti-IgG LB films have be en studied for application in immunosensors. The antibody (AB) LB films wer e horizontally deposited on glass and functionalized polymers, such as carb oxy-poly(vinyl chloride) (PVC-COOH), chloropropyl and aminopropyl sol-gel. The LB films were characterized by means of ellipsometry, atomic Force micr oscopy (AFM) and bicinchoninic acid (BCA) protein test. The interpretation of ellipsometric data was performed using a one-layer model. Non-specifical ly adsorbed protein was desorbed by washing the IgG film in 0.5 M NaCl, 2 M NaCl and 1% N-cetyl-N, N, N-trimethylammoniumbromide detergent solution re sulting in a 50% reduction of the film thickness. The mean thickness of an anti-IgG film on glass measured by ellipsometry, PVC-COOH and aminopropyl s ol-gel was 9 +/- 2, 11 +/- 1 and 23 +/- 8 nm, respectively. According to th e BCA test 6-8 mu g antibody (AB) per slide was bound to the functionalized polymers, but only 3 mu g AB per slide was adsorbed on glass. The average distance of anti-IgG grannies as indicated by AFM measurements on PVC-COOH, chloropropyl and aminopropyl sol-gel was 42 +/- 20, 34 +/- 3 and 23 +/- 4 nm. The average distance of granular AB structures on glass, however,was 15 0 +/- 50 nm. (C) 2000 Elsevier Science B.V. All rights reserved.