High spatial resolution label-free detection of antigen-antibody binding on patterned surface by imaging ellipsometry.

High spatial resolution and large area thickness mapping of label-free protein microarray has been achieved using imaging ellipsometry (IE) under optimized conditions. The protein patterns with feature size down to 8×8 μm(2) was readily imaged, and the binding between the surface immobilized antigen and the antibody was monitored. Quantitative thickness analysis of antibody-antigen binding on the 32×32 μm(2) micron spots was successfully performed, and we have obtained a limit of detection as low as 1.2 pg/spot. This work demonstrates that appropriately optimized IE could be used as a highly sensitive and high through-put label-free technique for studying surface antigen-antibody recognition in sub-40 μm scale.