Er³⁺ Sensitized 1530 nm to 1180 nm Second Near‐Infrared Window Upconversion Nanocrystals for In Vivo Biosensing

Abstract

Fluorescent bioimaging in the second near-infrared window (NIR-II) can probe deep tissue with minimum auto-fluorescence and tissue scattering. However, current NIR-II fluorophore-related biodetection in vivo is only focused on direct disease lesion or organ bioimaging, it is still a challenge to realize NIR-II real-time dynamic biosensing. A new type of Er sensitized upconversion nanoparticles are presented with both excitation (1530 nm) and emission (1180 nm) located in the NIR-II window for in vivo biosensing. The microneedle patch sensor for in vivo inflammation dynamic detection is developed based on the ratiometric fluorescence by combining the effective NIR-II upconversion emission and H O sensing organic probes under the Fenton catalysis of Fe . Owing to the large anti-Stokes shifting, low auto-fluorescence, and tissue scattering of the NIR-II upconversion luminescence, inflammation can be dynamically evaluated in vivo at very high resolution (200×200 μm).

Atomic‐Level Passivation of Individual Upconversion Nanocrystal for Single Particle Microscopic Imaging

“…[9,10] Research by Haro-González and co-workers demonstrates that the total fluorescence intensity of nanoparticle group not only depends on the number of particles, but also on the direction of the excitation polarization and the orientation of the UCNPs. studies obtained in the last decades are performed by a cluster of nanoparticles, which is quite different from that of an individual particle.…”

Physical Manipulation of Lanthanide‐Activated Photoluminescence

“…[46] Changing the excitation wavelength and power, or utilizing pulse excitation with tunable pulse width and frequency obviously affects the excitation process and thus the emission properties, not only intensity and color, but also decay time. Similar exploratory work by other groups has extended the upconversion excitation wavelength from 980 to 800 and 1532 nm, and achieved multicolor upconversion luminescence through controlling the excitation wavelength [48][49][50][51] ; Yuan et al [52] observed and intensified the silent upconversion emission bands of Er 3+ at 382, 472, 506, 560, and 618 nm from a single NaYF 4 :Yb/Er microcrystal via increasing the excitation power. Similar exploratory work by other groups has extended the upconversion excitation wavelength from 980 to 800 and 1532 nm, and achieved multicolor upconversion luminescence through controlling the excitation wavelength [48][49][50][51] ; Yuan et al [52] observed and intensified the silent upconversion emission bands of Er 3+ at 382, 472, 506, 560, and 618 nm from a single NaYF 4 :Yb/Er microcrystal via increasing the excitation power.…”

Recent Progress in Time‐Resolved Biosensing and Bioimaging Based on Lanthanide‐Doped Nanoparticles

“…Detection accuracy can be improved by using UCNPs as ratiometric fluorescent probes. Many substances, varying from inorganic ions to cells, have been detected with lanthanide‐doped UCNPs . Biosensing with UCNPs as labels is commonly based on the direct detection of upconversion luminescence or the luminescence resonance energy transfer signal.…”