Autofluorescence-Free In Vivo Imaging Using Polymer-Stabilized Nd³⁺-Doped YAG Nanocrystals

Abstract

Neodymium-doped yttrium aluminum garnet (YAG:Nd 3+ ) has been widely developed during roughly the last sixty years and has been an outstanding fluorescent material.It has been considered as the gold standard among multipurpose solid-state lasers. Yet, the successful downsizing of this system into the nano regimen has been elusive, so far. Indeed, the synthesis of a garnet structure at the nanoscale, with enough crystalline quality for optical applications was found to be quite challenging. Here, we present an improved solvothermal synthesis method producing YAG:Nd 3+ nanocrystals of remarkably good structural quality.Adequate surface functionalization using asymmetric double-hydrophilic block copolymers, constituted of a metal-binding block and a neutral water soluble block, provides stabilized YAG:Nd 3+ nanocrystals with a long term colloidal stability in aqueous suspensions. These newly stabilized nanoprobes keep the spectroscopic quality (long lifetimes, narrow emission lines, and large Stokes shift) characteristic of bulk YAG:Nd 3+ . The narrow emission lines of YAG:Nd 3+ nanocrystals are exploited by differential infrared fluorescence imaging, thus achieving an autofluorescence-free in vivo readout. In addition, nanothermometry measurements, based on the ratiometric fluorescence of the stabilized YAG:Nd 3+ nanocrystals, are demonstrated. The progress here reported paves the way for the implementation of this new stabilized YAG:Nd 3+ system in the preclinical arena.

Rapid Spectrometer-Free Luminescence-Based Detection of Tb3+ and Eu3+ in Aqueous Solution for Recovery and Urban Mining

“…61,64,65 As for trivalent lanthanides emitting in the IR region, such as Nd 3+ and Yb 3+ , a suitable sensitizer ligand can be implemented together with an SWIR camera, which then can be used for the luminescence detection. Photographic images of Nd 3+ luminescence with an SWIR camera are presented in the literature 68,69 and were already implemented for bio-imaging applications. 70 Another improvement can be the usage of a bandpass filter, so that only a selected wavelength and therefore a single rare earth element ion can be detected.…”

Near-infrared-II ratiometric fluorescence probes for non-invasive detection and precise navigation surgery of metastatic sentinel lymph nodes

“…Despite the excitement of NIR FGS for surgical resection of tumors, NIR-II (900-3000 nm) contrast agents have been shown to be superior to clinical NIR-I imaging agents with improved penetration depth and imaging contrast [36][37][38][39][40][41][42][43]. Several influential studies have applied ratiometric strategy for in vivo detection of various analyte such as ClO -, ONOO -, and GSH [44][45][46][47][48].…”

2D Thermal Maps Using Hyperspectral Scanning of Single Upconverting Microcrystals: Experimental Artifacts and Image Processing

“…In the recent literature, lanthanide (Ln 3+ )-doped materials are among the most promising candidates for contactless temperature sensors at the micro- and nanoscale over a wide temperature range. ,− Ln 3+ -doped materials often combine high accuracy, high photostability, and low toxicity, allowing high spatial and thermal resolutions when performing temperature sensing at the single-particle level. , It is worth noting that, besides nanothermometry, there is a broad range of other relevant applications that require understanding and exploiting the properties of Ln 3+ -doped materials. Some remarkable examples include solar energy conversion, super-resolution microscopy, quantum computing, fingerprint imaging, and biological applications …”

“…Some remarkable examples include solar energy conversion, 10 super-resolution microscopy, 11 quantum computing, 12 fingerprint imaging, 13 and biological applications. 14 Thermometers based on Ln 3+ often work by absorbing two or more photons of low energy (usually in the near-infrared) and emitting one with higher energy (usually in the visible spectrum). 15 This photon energy upconversion (UC) process is particularly relevant for biological applications because nearinfrared radiation has a high tissue penetration depth and minimizes optical damage.…”