Monitoring energy distribution of nonradiative energy transfer and reabsorption process in an upconversion nanoparticle detection system

Abstract

Exploiting the energy transfer (ET) direction is important in nanoscale fluorescent detection systems. In a typical detection system based on ET, the quenching efficiency was evaluated by decrease of donor's emission intensity, but there exists reabsorption process apart from nonradiative ET process. Here, we propose a method to analyze the individual contribution of nonradiative ET and reabsorption to quenching efficiency. These two processes influence in a different way on the nanoplatform consisting of NaYF4:20%Yb,2%Er UCNPs and a sulfonyl modified cyanine dye. We find that nonradiative ET process contributes more than reabsorption and possesses a better detection sensitivity (2.27 folds). Our work presents a thorough understanding of detection process, which will be conducive in evaluating the sensitivity of similar detection systems.