  In this paper, we explore the 3D structure of light scattering from
dark-field illuminated live 3T3 cells in the presence of 40 nm gold
nanomarkers. For this purpose, we use a high resolution holographic microscope
combining the off-axis heterodyne geometry and the phase-shifting acquisition
of the digital holograms. A comparative study of the 3D reconstructions of the
scattered fields allows us to locate the gold markers which yield, contrarily
to the cell structures, well defined bright scattering patterns that are not
angularly titled and clearly located along the optical axis (z). This
characterization is an unambiguous signature of the presence of gold biological
nanomarkers, and validates the capability of digital holographic microscopy to
discriminate them from background signals in live ce
