Energy-Transfer Editing in Lanthanide-Activated Upconversion Nanocrystals: A Toolbox for Emerging Applications

Abstract

Advanced nanoscale synthetic techniques provide a versatile platform for programmable control over the size, morphology, and composition of nanocrystals doped with lanthanide ions. Characteristic upconversion luminescence features originating from the 4f–4f optical transitions of lanthanides can be achieved through predesigned energy transfer pathways, enabling wide applications ranging from ultrasensitive biological detection to advanced spectroscopic instrumentation with high spatiotemporal resolution. Here, we review recent scientific and technological discoveries that have prompted the realization of these peculiar functions of lanthanide-doped upconversion nanocrystals and discuss the mechanistic studies of energy transfer involved in upconversion processes. These advanced schemes include cross relaxation-mediated depletion, multipulse sequential pumping, and nanostructural configuration design. Our emphasis is placed on disruptive technologies such as super-resolution microscopy, optogenetics, nanolasing, and optical anticounterfeiting, which take full advantage of the upconversion nanophenomena in relation to lanthanide-doped nanocrystals.

Monodisperse Core-Shell NaYF4:Yb3+/Er3+@NaYF4:Nd3+-PEG-GGGRGDSGGGY-NH2 Nanoparticles Excitable at 808 and 980 nm: Design, Surface Engineering, and Application in Life Sciences

“…Lanthanide-doped upconversion nanoparticles (UCNPs) have recently attracted a great deal of attention as promising materials for various biomedical applications including medical diagnostics, mainly for in vitro and in vivo imaging, but also in longer perspective for drug and gene delivery, and photothermal and photodynamic therapy of malignancies (Duan et al, 2018;Qin et al, 2019). The particles also find utilization in sensing applications, such as environmental hazard detection, food assays, and biological analysis (Chen et al, 2014;Poláchová et al, 2019;Zhang et al, 2019).…”

Highly colloidally stable trimodal 125I-radiolabeled PEG-neridronate-coated upconversion/magnetic bioimaging nanoprobes

“…Compared to conventional fluorescence nanomaterials (e.g., organic dyes or metal complexes), UCNPs have several advantages, such as high chemical stability, large anti-Stokes shift, narrow emission lines, no blinking, and no bleaching 16 . UCNPs have great potential in a variety of applications, from photovoltaics, photocatalysis, security, and display technology to in vitro and in vivo tissue imaging, background-free biosensors, light-triggered drug and gene delivery, optogenetics, photodynamics and photothermal therapy [17][18][19][20][21][22] . The nanoparticles are also beneficial for multimodal in vivo bioimaging because simple variations of dopant ions in the crystal lattice can induce the formation of particles suitable for down-and upconversion luminescence, MRI, and CT imaging 23,24 .…”

Info-Convergence Ceramic Nanosystems

“…Upconversion materials have been extensively researched due to their inherent abilities. [57][58][59] In contrast to commonly used QDs and organic fluorophores, upconversion nanoparticles typically consist of an inorganic host matrix and lanthanide dopants embedded in the host lattice. Photon upconversion is a nonlinear optical process, in which successive absorption of two or more low-energy photons is followed by luminescent emission of high-energy photons.…”