Fabrication of Calix[4]arene Derivative Monolayers to Control Orientation of Antibody Immobilization

• Main Authors: Hongxia Chen, Feng Liu, Fangjie Qi, Kwangnak Koh, Keming Wang
• Format: Article
• Language: English
• Published: MDPI AG 2014-03-01
• Series: International Journal of Molecular Sciences
• Subjects: calixarene; surface plasmon resonance (SPR); Immunoglobulin G (IgG); orientation; dipole moment
• Online Access: http://www.mdpi.com/1422-0067/15/4/5496

Three calix[4]arene (Cal-4) derivatives which separately contain ethylester (1), carboxylic acid (2), and crownether (3) at the lower rim with a common reactive thiol at the upper rim were synthesized and constructed to self-assembled monolayers (SAMs) on Au films. After spectroscopic characterization of the monolayers, surface coverage and orientation of antibody immobilized on the Cal-4 derivative SAMs were studied by surface plasmon resonance (SPR) technique. Experimental results revealed that the antibody could be immobilized on the Cal-4 derivatives spontaneously. The orientation of absorbed antibody on the Cal-4 derivative SAMs is related to the SAM’s dipole moment. The possible orientations of the antibody immobilized on the Cal-4 derivative 1 SAM are lying-on or side-on, while on the Cal-4 derivative 2 and Cal-4 derivative 3 head-on and end-on respectively. These experimental results demonstrate the surface dipole moment of Cal-4 derivative appears to be an important factor to antibody orientation. Cal-4 derivatives are useful in developing site direct protein chips.