Colloidal CdSe-ZnS semiconductor quantum dots (QDs) have tunable narrow-band luminescence emission and high resistance to photodegradation, properties that make them promising for use as fluorescent labels in biotechnological applications such as fluoro-immunoassays and in cellular imaging. We have developed efficient methods for conjugating these inorganic fluorophores to antibodies via the use of a molecular adaptor protein, the B2 domain of streptococcal protein G appended with an electrostatic interaction domain, which acts as a bridge between the QD fluorophore and antibodies. In this approach, coupling of the adaptor to the QD is driven by electrostatic self-assembly, while bridging to the antibody is driven by specific interactions. In the present study, we present fluoro-immunoassay studies employing QD-antibody conjugates for the detection of low levels of the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). We will also explore the use of self-assembled QD-protein-receptor complexes in Foerster energy transfer assays, where the QD emission can be altered by a quenching dye receptor in a QD-protein-receptor conjugate.