  In the high density environments of circumstellar disks dust grains are
expected to grow to large sizes by coagulation. Somewhat unexpectedly, recent
near-IR observations of PAH features from disks around Herbig Ae/Be stars
demonstrate that substantial amount of dust mass in these disks (up to several
tens of per cent of the total carbon content) can be locked up in particles
with sizes ranging from several to tens of nanometers. We investigate the
possibility of detecting the electric dipole emission produced by these
nanoparticles as they spin at thermal rates (tens of GHz) in cold gas. We show
that such emission peaks in the microwave range and dominates over the thermal
disk emission at \nu < 50 GHz typically by a factor of several if > 5 % of the
total carbon abundance is locked up in nanoparticles. We test the sensitivity
of this prediction to various stellar and disk parameters and show that if the
potential contamination of the spinning dust component by the free-free and/or
synchrotron emission can be removed, then the best chances of detecting this
emission would be in disks with small opacity, having SEDs with steep sub-mm
slopes (which minimizes thermal disk emission at GHz frequencies). Detection of
the spinning dust emission would provide important evidence for the existence,
properties, and origin of the population of small dust particles in
protoplanetary disks, with possible ramifications for planet formation.
