Time‐Resolved FRET Biosensor Based on Amine‐Functionalized Lanthanide‐Doped NaYF4 Nanocrystals

Background elimination and improved sensitivity were achieved by time-resolved (TR) detection with a FRET biosensor for traces of biomolecules such as avidin at concentrations down to 4.8 nM. As shown in the picture, UV excitation of biotinylated NaYF4:Ce/Tb nanocrystals triggers energy transfer to fluorescein isothiocyanate (FITC), whose long-lived emission due to FRET can be distinguished from the short-lived background from direct excitation. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.