A turn-on upconversion fluorescence resonance energy transfer biosensor for ultrasensitive endonuclease detection

A facile one-step approach is proposed to make hydrophilic and DNA-functionalized upconversion nanoparticles through ligand exchange at the liquid–liquid interface, and an ultrasensitive and selective biosensor was designed for assaying nuclease activity and inhibition, based on FRET from the DNA-functionalized UCNPs to graphene oxide.