UV Emission from Lanthanide-Doped Upconversion Nanoparticles in Super-Resolution Microscopy: Potential for Cellular Damage

Abstract

Upconversion nanoparticles (UCNPs) co-doped with lanthanide ions have recently attracted significant attention as fluorescent probes for super-resolution microscopy (SRM). This is due to the advantages of UCNPs over other fluorescence probes, such as fluorescent proteins, owing to their unique optical properties, limited photobleaching, and sharp emissions. However, the concurrent emission of ultraviolet (UV) wavelength radiation by UCNPs and the potential for cell photodamage, which may limit useful live-cell analysis, have been overlooked. Here, UCNPs synthesized with eight commonly used combinations of Yb/Tm and Yb/Tm/Gd dopants were excited by either pulsed- or continuous-wave (CW) lasers to evaluate their UV emission. The ratio of emitted UV-A and UV-B was measured relative to blue emission at 475 nm, which is traditionally used for imaging during SRM. We demonstrate that most UCNP samples emit UV light and that the dopant concentration has a key role in generating UV emissions. In addition, the use of pulsed or CW lasers for excitation can lead to a large variation in the amount of UV emitted. This work highlights the importance of considering upconversion dopant composition and concentration, as well as analyzing the emission of synthesized UCNPs before their use to prevent unwanted cell photodamage during live-cell imaging by SRM. Moreover, it established a need to improve the visible light emission of UCNPs with respect to UV emission for SRM applications.

Few-mode optical fiber-based flexible pressure feedback tentacle doped with fluorescence temperature pointer

“…The structure diagram of the sensor proposed in this paper is shown in figure 1(a), FMF with coating corrosion was encapsulated into water droplets using PDMS elastomer and doped with heat-sensitive UCNPs (NaYF 4 :Yb, Er@NaYF 4 ) to achieve temperature compensation. Compared with fluorescent materials such as Rhodamine and quantum dots, UCNPs shows unique properties when doped with lanthanide ions [35]. Not only do they effectively convert low-energy nearinfrared (NIR) radiation into high-energy visible light emission, they also have many compelling advantages, such as narrow emission peaks, excellent light stability, and improved detection sensitivity [36,37].…”