Neodymium‐Doped LaF₃ Nanoparticles for Fluorescence Bioimaging in the Second Biological Window

Abstract

The future perspective of fluorescence imaging for real in vivo application are based on novel efficient nanoparticles which is able to emit in the second biological window (1000-1400 nm). In this work, the potential application of Nd(3+) -doped LaF(3) (Nd(3+) :LaF(3) ) nanoparticles is reported for fluorescence bioimaging in both the first and second biological windows based on their three main emission channels of Nd(3+) ions: (4) F(3/2) →(4) I(9/2) , (4) F(3/2) →(4) I(11/2) and (4) F(3/2) →(4) I(13/2) that lead to emissions at around 910, 1050, and 1330 nm, respectively. By systematically comparing the relative emission intensities, penetration depths and subtissue optical dispersion of each transition we propose that optimum subtissue images based on Nd(3+) :LaF(3) nanoparticles are obtained by using the (4) F3/2 →(4) I11/2 (1050 nm) emission band (lying in the second biological window) instead of the traditionally used (4) F(3/2) →(4) I(9/2) (910 nm, in the first biological window). After determining the optimum emission channel, it is used to obtain both in vitro and in vivo images by the controlled incorporation of Nd(3+) :LaF(3) nanoparticles in cancer cells and mice. Nd(3+) :LaF(3)nanoparticles thus emerge as very promising fluorescent nanoprobes for bioimaging in the second biological window.

Neodymium-doped nanoparticles for infrared fluorescence bioimaging: The role of the host

“…Two years later, Rocha et al reported the first infrared deep-tissue in vivo image of a mouse after intravenous injection of LaF 3 :Nd 3þ NPs (Figure 1(b)). 34,35 In this case, a preferential accumulation of the Nd:NPs in the liver and the spleen was evidenced by recording (with a Si-based camera) the spatial distribution of the intense 1060 nm fluorescence (corresponding to the 4 F 3/2 ! 4 I 11/2 transition) generated under 808 nm optical excitation.…”

Nd3+ doped LaF3 nanoparticles as self-monitored photo-thermal agents

“…35 In addition to all these properties, Nd 3þ :LaF 3 NPs also show fluorescence bands with a remarkable thermal sensitivity. 32 Based on all these properties, Nd 3þ :LaF 3 -NPs have been recently used for single cell imaging, sub-tissue thermal sensing, and for in vivo fluorescence imaging.…”

“…32 Based on all these properties, Nd 3þ :LaF 3 -NPs have been recently used for single cell imaging, sub-tissue thermal sensing, and for in vivo fluorescence imaging. 35 Light-to-heat conversion in Nd 3þ :LaF 3 -NPs, not explored yet, would emerge as an important additional feature that would place Nd 3þ :LaF 3 -NPs in a privilege position among other NPs as they could be used in a multifunctional manner for simultaneous bio-imaging, photo--thermal treatment, and temperature control of the irradiated area, all these facilities with the very same biocompatible nanoprobes.…”

Crystal structure, NIR luminescence and X-ray computed tomography of Nd3+:Ba0.3Lu0.7F2.7 nanospheres

“…Among lanthanides, Nd 3+ is particularly interesting because it is excited and emits within the first and second biological windows (650 nm -950 nm and 1000-1400 nm), in which the radiation is weakly attenuated by tissues and can penetrate more deeply than the visible light, thus improving the sensitivity of the assays and lowering tissue damage. 6,7,8,9 Most of the Ln 3+ -doped rare earth-based matrices classically studied, such as oxides, vanadates, phosphates, etc., show associated phonon energies that are usually very high resulting in low luminescent efficiencies due to the enhancement of non-radiative pathways. 10 A straightforward solution to this problem came with the development of fluoride-based matrices, which showed a high luminescent efficiency due to their low phonon energies.…”