  Quantum description of mulitiparticle nano-systems is studied in a hot and
dense electromagnetic medium. We use renormalization techniques of quantum
field theory to show that the electromagnetic properties like electric
permittivity and magnetic permeability depend on the temperature and density of
the media. Casimir force also depends upon the physical properties of the
medium and becomes a function of these parameters within the nano-systems. We
discuss the effect of the Casimir force on the nanosystems in terms of
temperature and density of the system. We present carbon nanotubes and
biomolecules as examples.
