Long‐Term Real‐Time Tracking of Lanthanide Ion Doped Upconverting Nanoparticles in Living Cells

Abstract

A track record: Upconverting nanoparticles (UCNPs) were tracked in living HeLa cells and their active transport by motor proteins was visualized in real time. The remarkable photostability of the UCNPs and the noninvasiveness of near‐infrared excitation allowed continuous observation of living cells for as long as 6 h.

Single-Molecule Fluorescence and in Vivo Optical Traps: How Multiple Dyneins and Kinesins Interact

“…In addition, since UCNPs up-convert two long-wavelength photons, the excitation causes minimal cellular auto-fluorescence. 83 Another technique, bFIONA (bright-Field Imaging with One- Nanometer Accuracy), uses brightfield imaging of highly absorbing particles. It was demonstrated on melanophores, which contain dark melanin-containing vesicles.…”

Atomistic evolution during the phase transition on a metastable single NaYF4:Yb,Er upconversion nanoparticle

“…Among UCNPs, the Yb 3+ -sensitized Er 3+ system in NaYF 4 nanocrystalline matrices (NaYF 4 :Yb,Er) is considered to be one of the most efficient UCNPs under NIR reported to date, where NaYF 4 :Yb,Er emits green/red light under the excitation of 980 nm NIR light 3,6,7 . Er 3+ ions are the activators (emitters) for upconversion photoluminescence and Yb 3+ is the sensitizer in NaYF 4 .…”

Functionalized Upconversion Nanoparticles: Versatile Nanoplatforms for Translational Research

“…Such remarkable photostability together with low cytotoxicity of UCNPs enabled real-time visualization of intracellular movements of UCNPs, as demonstrated through the use of amphiphilic PEG-phospholipids coated UCNPs as the tracking particles in single living HeLa cells [42]. No obvious cell death caused by continuous 980 nm laser illumination was observed, a prerequisite for real-time and long term particle tracking of UCNPs.…”

“…(C) The mean square displacements (MSD) plots for phases II-IV. Reprinted with permission from [42]. …”

“…First, upconversion luminescence (UCL) is a unique process where low energy continuous-wave (CW) of near-infrared (NIR) light is converted to higher energy light through the sequential absorption of multiple photons or energy transfer [34], which exhibits attractive optical features such as sharp emission lines [35, 36], long lifetimes (~ms) [37], large anti-Stokes shift [35], superior photo-stability [38], high detection sensitivity [39], non-blinking and non-bleaching [38, 40], high tissue penetration depth [41], minimal photo-damage[42] and lack of autofluorescence [43, 44]. Second, with the doping of well-selected lanthanide ions of Gd 3+ , Er 3+ /Yb 3+ and Tm 3+ /Yb 3+ (or combination of these ions), MRI and multicolor UCL imaging (emission bands ranging from ultraviolet [UV] to NIR region) could be readily achieved [45-48].…”