Upconversion: Tunable Near Infrared to Ultraviolet Upconversion Luminescence Enhancement in (α‐NaYF₄:Yb,Tm)/CaF₂ Core/Shell Nanoparticles for In situ Real‐time Recorded Biocompatible Photoactivation (Small 19/2013)

Abstract

Upconversion nanoparticles (UCNPs) can convert tissue‐penetrable nearinfrared light into UV emission, making them promising as transducers for photoactivation in biology. However, the choice of the UV emitting UCNPs is limited and their NIR‐to‐UV efficiency is low. G. Han and co‐workers have addressed this issue by developing a family of CaF2‐coated UCNPs with tunable UV enhancement. As reported , such design outperforms known optimal UCNPs and in situ realtime live‐cell photoactivation is recorded for the first time with such nanoparticles. This result is a potential game changer in photoactivation in living systems and a new tool for other biophotonic applications.

Synthesis of Multicolor Core/Shell NaLuF4:Yb3+/Ln3+@CaF2 Upconversion Nanocrystals

“…However, the possible leaking of rare earth ions from the host lattice could possibly lead to diseases such as nephrogenic systemic fibrosis [44,45]. Compared with lanthanide fluorides, calcium fluoride (CaF 2 ) has unique advantages owing to its superior biocompatibility and high optical transparency [46,47,48,49,50,51]. It has recently been demonstrated that CaF 2 also has low lattice mismatch with NaReF 4 nanocrystals, and can efficiently prevent rare-earth ions from leaking [46,50].…”

Near‐Infrared Photoinduced Reactions Assisted by Upconverting Nanoparticles

“…High‐intensity NIR light can overheat and damage biological components . The overheating problem can be partially addressed using suitable sensitive compounds, high‐efficient UCNPs, and UCNPs that can be excited by 808 nm light . Second, penetration depth of NIR light is important for deep‐tissue biomedical applications.…”

“…Chem.E ur.J. 2017,23,[8325][8326][8327][8328][8329][8330][8331][8332] www.chemeurj.org Concept UCNP and ap hotosensitive compound is so close that non-radiative energy transfer from the excited UCNP to the photosensitivec ompound may happen. Thus, the efficiency of the photoreaction at the surfaces of UCNPs is highert han that in solution.…”

“…[34] High-intensity NIR light can overheat and damage biological components. [7b, 10, 19c, 35] The overheatingp roblem can be partially addressed using suitable sensitive compounds, [10, 19c] high-efficient UCNPs, [23] and UCNPs that can be excited by 808 nm light. [35] Second, penetration depth of NIR light is important for deep-tissue biomedical applications.S everal groups have reported that 980 nm light can pass throughafew millimeters thick tissues and induce UCNPassisted photochemistry.…”

Effects of trisodium citrate on morphology of β-NaGd1−x Yb x F4:Er3+ nanocrystals: role of Yb3+ concentration

“…-rich NaREF 4 UCNPs are sometimes needed for special purpose, usually the same synthesis condition as preparing Yb 3? slightly doped counterpart was adopted directly [47][48][49]. However, we found in this work that the critical molar ratio of Cit:Ln is dependent on the Yb 3?…”