Sensing Using Rare-Earth-Doped Upconversion Nanoparticles

Abstract

Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit.

Determining the 3D orientation of optically trapped upconverting nanorods by in situ single-particle polarized spectroscopy

“…[19][20][21][22] In addition, intracellular studies based on single UCNP are nowadays a real possibility as the synthesis of ultra-small (<10 nm in diameter) UCNPs showing large NIR-to-VIS optical conversion efficiencies has been recently demonstrated. 23 As a consequence, UCNPs are also being considered as promising † Electronic supplementary information (ESI) available: Polarized emission of the colloidal suspension of NaYF 4 optical probes for experiments at single-cell and singleparticle levels. As a result of the intensive research carried out on UCNPs during the last few years, a wide range of UCNPs consisting of different host lattices and dopants have appeared onto the scene.…”

“…As a result of the intensive research carried out on UCNPs during the last few years, a wide range of UCNPs consisting of different host lattices and dopants have appeared onto the scene. 4,24,25 Modifying the different synthesis parameters different emission bands, 12 particle sizes 23 and morphologies 3,4,13,[26][27][28] could be achieved. Among all of them, erbium and ytterbium codoped NaYF 4 UCNPs are considered as the reference combination of dopants and host materials.…”

“…4,24,25 Modifying the different synthesis parameters different emission bands, 12 particle sizes 23 and morphologies 3,4,13,[26][27][28] could be achieved. Among all of them, erbium and ytterbium codoped NaYF 4 UCNPs are considered as the reference combination of dopants and host materials. 13,23 In particular, the recently demonstrated possibility of synthesizing NaYF 4 :Er 3+ ,Yb 3+ upconverting nanorods (hereafter NaYF 4 :Er 3+ ,Yb 3+ UCNRs) appears to be especially interesting as they constitute a unique system that could be used in a wide range of applications including security inking, cell tracking, cell manipulation, and bottom-up fabrication of nanofluidic and optical devices.…”

Assessing Single Upconverting Nanoparticle Luminescence by Optical Tweezers

“…Note that this is of crucial importance as several works have already pointed out a possible dependence of UCNP luminescence on their surrounding environment. [23][24][25] In fact, the measurement of the luminescence spectrum generated by a single UCNP suspended in water is a challenging task. It implies the remote immobilization of a single UCNP that, otherwise, would move randomly (Brownian motion) and, thus, will be continuously escaping from the excitation beam.…”

Portable optical fiber probe for in vivo brain temperature measurements

“…Typically rare-earth thermometry technique utilizes upconversion emission, where the relevant spectrum is emitted at a shorter wavelength than the excitation light [19]. This is especially important in an application involving in vivo measurements, as alternative optical methods which rely on excitation and collection using UV or visible light can be strongly influenced by background autofluorescence from the surrounding tissue [20].…”