Multichannel surface imaging and analysis of self-assembled monolayers and proteins

Abstract

Multichannel images of 11-Mercaptoundecanoic acid and 11-Mercapto-1-undecanol self-assembled monolayers (SAMs) together with a biospecific interferon-gamma (IFN-gamma)/anti-IFN-gamma antibody immunoreaction were observed by two-dimensional surface plasmon resonance (2D-SPR) imaging system. Patterning process for SAM was simplified by exploiting direct photooxidation of thiol bonding (photolysis) instead of conventional photolithography. Sharper images were resolved by using a white light source in combination with a narrow bandpass filter, minimizing the diffraction patterns on the images. The line profile calibration of the image contrast caused by different resonance conditions at each points on the sensor surface enabled us to discriminate the monolayer thickness in a sub-nanometer scale. For protein patterning, a precipitation scheme induced by biocatalytic reaction was implied for the signal amplification. Specific binding of IFN-gamma antigen with surface-immobilized antibody was found detectable down to the concentration of 1 ng/mL.