In this paper, we study how the optical properties of gold nanoparticles and core-gold nanoshells are changed as a function of different sizes, shapes, composition and biomolecular coating with characteristic shifts towards near-infrared region, 750-900nm. We show that the optical tunability in this region can be carefully checked for particle sizes falling in the range 100-150nm. Such tunability in the range 750-900 nm is particularly important in biosystems, because the high transmittivity properties characterizing many biological tissues.