A Versatile Strategy for Constructing Ratiometric Upconversion Luminescent Probe with Sensitized Emission of Energy Acceptor

Abstract

When fabricating ratiometric optical probes using lanthanide-doped upconversion nanoparticles (UCNPs), which are promising luminescent materials that have widely been utilized in biosensing and bioimaging as energy donors, it is still a challenge to obtain the emission signal of energy acceptors with reasons unclear so far. Herein, we reveal that the energy-transfer efficiency and brightness of UCNPs as well as the aggregation-caused quenching (ACQ) of energy accepting dyes are the main factors restricting the emission of energy acceptors, and we have circumvented this problem by modulating the structure of UCNPs and the assembly manner of the energy donor−acceptor pair. On this basis, a proof-ofconcept ratiometric upconversion nanoprobe was constructed for hydrogen sulfide (H 2 S) detection with an elaborate dye Fl-1 as an energy acceptor. As the H 2 S concentration increased, the emission intensity of Fl-1 at 525 nm increased gradually, accompanied by a decrease of upconversion luminescence at 480 nm, thus providing a ratiometric signal of F 480 /F 525 dependent on the H 2 S concentration. This probe was able to track H 2 S in living cells and zebrafish and visualize the H 2 S level of mice in physiological processes.

Ratiometric upconversion luminescence nanoprobes from construction to sensing, imaging, and phototherapeutics

“…Thus, a unique type of ratiometric UCL nanoprobes can be constructed by plotting a functioning relationship of the "U/F" or "F/U" ratio vs. target concentration (or the condition). [88][89][90][93][94][95]99,106,140,149,155,159,162 During the practical process of sensing applications, to acquire highly sensitive ratiometric UCL signal outputs in response to targets, the changes in U 1 /U 2 ratiometric values in the presence of targets should be remarkable enough, while very small changes in target concentration (condition) can be effectively distinguished through observable changes in U 1 /U 2 ratiometric values. In the well-plotted linear relationship of U 1 /U 2 vs. the target concentration (Scheme 2b), there is enough large positive slope.…”

“Dual-Lock-Dual-Key” Controlled Second Near-Infrared Molecular Probe for Specific Discrimination of Orthotopic Colon Cancer and Imaging-Guided Tumor Excision

“…The normalized data indicated that the H 2 S level in HCT-116 cells was approximately 4-5 folds higher than that of MCF-7 cells (Figure 5B), which was in agreement with the previously reported H 2 S concentration measured using a ratiometric H 2 S probe. 41 The differentiation of tumor type was further conducted at living-body level. HCT-116 tumor-bearing mice with high H 2 S expression and MCF-7 tumor-bearing mice with low H 2 S expression were selected for tests.…”

In Vivo Monitoring of Hydrogen Polysulfide via a NIR-Excitable Reversible Fluorescent Probe Based on Upconversion Luminescence Resonance Energy Transfer

“…When the concentration of H 2 S n decreased, SiR2 released H 2 S n and returned to SiR1, accompanying with the recovery of absorption and weakened UCL. In this process, the green UCL emission at 545 nm showed a slighter change than the red UCL emission because of the interrelation between these two UCL emission peaks, , which can be utilized as an internal standard signal for constructing a ratiometric probe to eliminate the interferences caused by the uneven distribution of probes and variations of the biological environment and instrument. , With the as-prepared nanoprobe, we can dynamically monitor the concentration changes of H 2 S n in living cells and mice.…”