Dye-Sensitized Lanthanide-Doped Upconversion Nanoparticles for Water Detection in Organic Solvents

Abstract

The use of fluorescent probes to detect water content in organic solvents is highly desirable in chemical industries. Optimal fluorescent probes are expected to achieve rapid tests with a high sensitivity. Most existing fluorescent probes use water as a quencher to turn off the fluorescence and are not able to detect water in very low concentrations. We report a nanoformulation containing lanthanide-doped upconversion nanoparticles (UCNPs) coated with a very high concentration of ICG to detect water content in organic solvents via a turn-on process with an ultrahigh sensitivity at the ppm level. It is based on our unexpected observation that UCNPs coupled to a high concentration of ICG dye and dispersed in an organic solvent exhibit enhancement of emission upon addition of water. A turnoff detection process can also be achieved when the water content is higher (>0.2% v/v, 2000 ppm). We propose the underlying sensitization mechanism as involving the interaction of polar water with ICG, influencing the quenching between dye molecules and energy transfer from dye molecules to UCNPs. We hope our approach could provide a guide for the design of fluorescent nanosensors for water detection in organic solvents and also deepen the understanding of the energy transfer processes from organic dye to UCNPs.

Toward Upconversion Luminescence Enhancement with Dye Sensitization

“…< 1% v/v). Sensitizing UCNPs with ICG at high concentration (>20 μg mL –1 ) can realize a turn-on detection of very low water concentrations (0.0008% v/v) (Figure c) . Furthermore, these ICG-sensitized UCNPs have been demonstrated to display a turn-off detection process at higher water content (>0.2% v/v, 2000 ppm).…”

“…(c) Schematic illustration of the fabrication of dye-sensitized fluorescent nanosensors to achieve the turn-on detection of water in organic solvents. Reprinted with permission from ref . Copyright 2021 American Chemical Society.…”

“…Sensitizing UCNPs with ICG at high concentration (>20 μg mL −1 ) can realize a turn-on detection of very low water concentrations (0.0008% v/v) (Figure 7c). 48 Furthermore, these ICG-sensitized UCNPs have been demonstrated to display a turn-off detection process at higher water content (>0.2% v/v, 2000 ppm). The PDT effect of ICG-sensitized UCNPs indicated that the tumor apoptosis rate reached 85.3%, the tumor volume decreased 66% with ICG-sensitized UCNPs, and there were no damage and toxicity to normal tissues (Figure 7d).…”

Energy transfer between optically trapped single ligand-free upconversion nanoparticle and dye

“…In another recent work, self-made optical tweezers integrated upconversion luminescence confocal scanning instrument is employed for in situ imaging of a single suspension cell via efficient LRET [43]. The interaction between the dyes and UCNPs has been a subject of intense research wherein studies that focus on the role of particle size [44], the distance between the dye and the core UCNPs, the role of dopant, etc have been carried out [45,46]. However, not much work has been done at a single particle level that is optically arrested in a medium of dye solution.…”

Complexing Eu3+/Tb3+ in a Nanoscale Postmodified Zr-MOF toward Temperature-Modulated Multispectrum Chromism

“…To the best of our knowledge, this is the highest absolute sensitivity observed for MOF-based luminescent thermometers operating with a very broad temperature range from 25 to 400 K. The absolute sensitivity of this material further increased up to 6% K –1 in the cryogenic range (25–100 K). Furthermore, electron–phonon coupling interaction between Ln 3+ and the lattice was studied to understand the energy transfer between Zr-ctpy-NMOF and Ln 3+ ion. − …”