TR-FRET uses long-lifetime lanthanide chelates as donor fluorophores. By applying time-delayed signal detection, background interference is substantially reduced, resulting in improved signal-to-background ratio and assay sensitivity. This makes TR-FRET particularly suitable for homogeneous assays. In contrast, conventional FRET assays rely on short-lifetime organic fluorophores and are more susceptible to interference from autofluorescence and light scattering.