Abstract: This talk will discuss optical phenomena in nanostructures exhibiting strong signatures of many-particle interactions. In atomic absorption spectra, the Fano effect is an asymmetric line arising from the interference between a discrete state and a continuum of states.  Recently a similar effect has been seen in InAs quantum dots capped with GaAs. Here, the interference arises from competing absorption paths into conduction band: one from a valence electron and the other from a valence level coupled to the two-dimensional band. More intense radiation enhances the second path, producing a clear Fano line shape. Previously, demonstration of this nonlinear Fano effect with atoms was not possible because of the enormous radiation flux required to create the effect. In contrast to the optics of atoms, semiconductor quantum dots may be coupled with the Fermi gas of electrons. This is realized very simply by placing a quantum dot in the vicinity of a metal film. Then, new exciton states, Kondo excitons, can be formed. Such states and associated spin-flip phenomena have now attracted considerable interest from experimentalists. Semiconductor nanoparticles can also be made to strongly interact with bio-molecules and proteins. One of the main mechanisms of interaction in these bio-inspired nanosystems is Coulomb coupling. Potential applications of bio-inspired nanostructures include sensors and light-harvesting systems.