Methods of producing light in liquid media are provided using nanoparticles capable of generating electroluminescence when stimulated by an electrical signal. The nanoparticles are provided as a label on a target species or on a specific binding partner of the target species to be detected in a test method. The nanoparticle-labeled species are drawn into operable proximity to electrodes which, when energized by a power source, excite the nanoparticles to produce electroluminescence. Methods of performing binding assays are described using the disclosed methods.