Rare-earth-doped nanocrystals have become sought-after materials for cellular bioprobes because of their long emission lifetimes and low cytotoxicity. Researchers have now discovered how to make these probes even brighter by coupling them to gold nanorods materials that can induce field-enhanced fluorescence through surface plasmon resonances. They optimized this effect by systematically varying the thickness of a protective silica coating sandwiched between the gold nanorods and the doped nanocrystals.