Santanu,
Antibodies generally do not bind on their own to a bare Au surface; you
will need a linker. I suggest this paper:
@Article{thiol-protocol,
author = {Nikin Patel and Martyn C. Davies and Mark Hartshorne and
Richard J. Heaton and Clive J. Roberts and Saul
J. B. Tendler and Philip M. Williams },
title = {Immobilization of Protein Molecules onto Homogeneous
and Mixed Carboxylate-Terminated Self-Assembled
Monolayers},
journal = {Langmuir},
year = 1997,
volume = 13,
number = 24,
pages = {6485-90}
}