We demonstrate that novel oligonucleotide-modified gold nanoparticle probes hybridized to fluorophore-labeled complements can be used as both transfection agents and cellular "nano-flares" for detecting mRNA in living cells. Nano-flares take advantage of the highly efficient fluorescence quenching properties of gold, cellular uptake of oligonucleotide nanoparticle conjugates without the use of transfection agents, and the enzymatic stability of such conjugates, thus overcoming many of the challenges to creating sensitive and effective intracellular probes, Nano-flares exhibit high signaling, have low background fluorescence, and are sensitive to changes in the number of RNA transcripts present in cells.