Energy Transfer Probing as the Method for Testing Rare-earth Ions Doped “green” Nanoparticles as Fluorescent Agent for Bioimaging

Abstract

In spite of tremendous number of papers concerning rare-earth (RE) doped fluorescent nanoparticles (NP) and methods of their synthesis (see, for example, paper in Nature Photonics the problem of fluorescent quenching caused by —OH molecular vibrations is still not raised properly. The reason might be that most of the papers are devoted to the up-conversion fluorescent nanoparticles with the energy of emitted photons in the visible or even in UV spectral ranges. In this case the contribution of the quenching caused by the —OH groups to the overall relaxation rate is not so significant due to very high energy of optical transitions. However, in the near IR spectral range the input of the —OH groups to fluorescence quenching is significant, but until recently there were only few papers, which are raising this issue.