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Luminescent biosensing in the second nearinfrared (NIR-II) region is featured with superior spatial resolution and high penetration depth by virtue of the suppressed scattering of long-wavelength photons. Hitherto, the reported NIR-II nanoprobes are mostly based on carbon nanotubes, organic fluorophores or semiconducting quantum dots. As an alterna...
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... Ln 3+ -doped nanoparticles (NPs) are particularly intriguing owing to their superior properties, including high stability against photobleaching, long-lived (μs-ms) luminescence for timegated detection, and narrow emission bands for multiplexed sensing [31,[44][45][46][47][48][49][50][51][52][53][54][55] ) were reported to produce NIR-II light ( Fig. 1), but the NIR-II quantum yields (QYs) of most Ln 3+ -doped NPs were still too low to fulfill their practical application in luminescent biosensing. As such, continuous efforts were dedicated to developing highly efficient Ln 3+ -doped NIR-II luminescent nano-bioprobes. Although several classes of NIR-II luminescent probes like organic ...
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... and organic chromophore probe IR1061 with strong absorption at 800-1,100 nm were encapsulated in polycaprolactone. In the absence of H 2 O 2 , the 980 nm emission (I 980 ) of Er 3+ was suppressed due to the strong absorption of IR1061. Nevertheless, H 2 O 2 may induce the destruction of IR1061, and thus weaken its absorption from 800 to 1,100 nm (Fig. 10a). As a result, I 980 may gradually recover with increasing of the H 2 O 2 concentration. By contrast, the intensity of 1,180 nm emission (I 1180 ) of Ho 3+ was not affected by H 2 O 2 . Therefore, the concentration of H 2 O 2 can be quantified by determining the PL intensity ratio I 980 /I 1180 (Fig. 10b). As a proof-of-concept ...
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... weaken its absorption from 800 to 1,100 nm (Fig. 10a). As a result, I 980 may gradually recover with increasing of the H 2 O 2 concentration. By contrast, the intensity of 1,180 nm emission (I 1180 ) of Ho 3+ was not affected by H 2 O 2 . Therefore, the concentration of H 2 O 2 can be quantified by determining the PL intensity ratio I 980 /I 1180 (Fig. 10b). As a proof-of-concept experiment, they fabricated the microneedle patches based on the NaErF 4 :Ho@NaYF 4 NPs and IR1061 encapsulated polycaprolactone, which were applied for in vivo bioassay of H 2 O 2 in the inflammation site (Fig. 10c). By taking advantage of low autofluorescence of the NIR-II emission, the PL images of the ...
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... the concentration of H 2 O 2 can be quantified by determining the PL intensity ratio I 980 /I 1180 (Fig. 10b). As a proof-of-concept experiment, they fabricated the microneedle patches based on the NaErF 4 :Ho@NaYF 4 NPs and IR1061 encapsulated polycaprolactone, which were applied for in vivo bioassay of H 2 O 2 in the inflammation site (Fig. 10c). By taking advantage of low autofluorescence of the NIR-II emission, the PL images of the microneedle array can be clearly observed under the skin tissue of mice. Upon excitation at 1,530 nm, the PL signal of 1,180 nm was stable while the signal of 980 nm gradually increased as the evolution of inflammation with the continuous ...
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... taking advantage of low autofluorescence of the NIR-II emission, the PL images of the microneedle array can be clearly observed under the skin tissue of mice. Upon excitation at 1,530 nm, the PL signal of 1,180 nm was stable while the signal of 980 nm gradually increased as the evolution of inflammation with the continuous generation of H 2 O 2 (Fig. 10d). According to the linear correlation between H 2 O 2 concentration and log(I 980 /I 1180 ), the concentration deviation of H 2 O 2 in the inflammatory site can be monitored from 0 to 12 h, which provides a feasible strategy for the quantitative detection of disease markers in ...
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... at 790 nm. In their work, the integrated intensity ratio of Yb 3+ and Nd 3+ NIR-II emissions was found to decrease with the temperature from 10 to 50°C. A 4-fold higher sensitivity (0.44%/°C) was achieved than that of LaF 3 :Nd/Yb core-only NPs. Moreover, the proposed nanothermometer enabled monitoring of the real-time subcutaneous temperature (Fig. 11). After laserinduced heating, the subcutaneous temperature variation can be identified by the luminescent nanothermometry in a living animal (Fig. 11d) Cr/Nd NPs presented an outstanding sensitivity of 4.89%/°C, which was one order of magnitude higher than that of the vast majority of lu- minescent thermometers. However, the emission of ...
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... 50°C. A 4-fold higher sensitivity (0.44%/°C) was achieved than that of LaF 3 :Nd/Yb core-only NPs. Moreover, the proposed nanothermometer enabled monitoring of the real-time subcutaneous temperature (Fig. 11). After laserinduced heating, the subcutaneous temperature variation can be identified by the luminescent nanothermometry in a living animal (Fig. 11d) Cr/Nd NPs presented an outstanding sensitivity of 4.89%/°C, which was one order of magnitude higher than that of the vast majority of lu- minescent thermometers. However, the emission of Cr 3+ ions (820-840 nm) located in NIR-I region, which to some extent restricted their applications for temperature sensing in vivo. Very recently, ...
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... which to some extent restricted their applications for temperature sensing in vivo. Very recently, several interesting studies were reported by employing the hybrid structured nanothermometers for sensitive temperature sensing [119,[124][125][126][127]. Rodrí- guez et al. [119] designed a hybrid nanothermometer for subtissue temperature sensing (Fig. 12). This hybrid nanothermometer was prepared following a double-emulsion encapsulation procedure by PbS/CdS/ZnS QDs as temperature-sensitve response unit and temperature-insensitive NaGdF 4 :Nd as internal standard unit for the deep tissue ratiometric thermal sensing (Fig. 12b). The thermal sensitivity of the developed hybrid ...
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... [119] designed a hybrid nanothermometer for subtissue temperature sensing (Fig. 12). This hybrid nanothermometer was prepared following a double-emulsion encapsulation procedure by PbS/CdS/ZnS QDs as temperature-sensitve response unit and temperature-insensitive NaGdF 4 :Nd as internal standard unit for the deep tissue ratiometric thermal sensing (Fig. 12b). The thermal sensitivity of the developed hybrid nanostructures was determined to be 2.5%/°C, which was one order of magnitude higher than that of the available NIR-I nanothermometers [128,129]. Subsequently, Xu et al. [124] further improved the thermal sensitivity. Triplettriplet annihilation (TTA) dyad was modified on the surface of ...
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... was determined to be 2.5%/°C, which was one order of magnitude higher than that of the available NIR-I nanothermometers [128,129]. Subsequently, Xu et al. [124] further improved the thermal sensitivity. Triplettriplet annihilation (TTA) dyad was modified on the surface of NaYF 4 :Nd to design an organic/inorganic hybrid ratiometric thermometer (Fig. 13). The proposed organic/inorganic hybrid nanothermometer was applied to monitor the specific temperature variations and map the temperature distributions in the inflammatory mode, which exhibited high thermal sensitivity (~7.1%/°C) and resolution (~0.1°C). Nevertheless, the emission of TTA lay in the visible region, and double beam ...
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... to monitor the specific temperature variations and map the temperature distributions in the inflammatory mode, which exhibited high thermal sensitivity (~7.1%/°C) and resolution (~0.1°C). Nevertheless, the emission of TTA lay in the visible region, and double beam excitations combined with two detectors (PMT and InGaAs detectors) were required (Fig. 13a). In addition, different attenuation through tissue of the emission signal of 540 nm from TTA and 1,060 nm from NaYF 4 :Nd might deteriorate the measurement accuracy in vivo. NPs provide unique opportunities for simultaneous multiplexed assay of different disease markers in deep tissue. Last but not the least, the prevailing in vivo ...
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... Ln 3+ -doped nanoparticles (NPs) are particularly intriguing owing to their superior properties, including high stability against photobleaching, long-lived (μs-ms) luminescence for timegated detection, and narrow emission bands for multiplexed sensing [31,[44][45][46][47][48][49][50][51][52][53][54][55] ) were reported to produce NIR-II light ( Fig. 1), but the NIR-II quantum yields (QYs) of most Ln 3+ -doped NPs were still too low to fulfill their practical application in luminescent biosensing. As such, continuous efforts were dedicated to developing highly efficient Ln 3+ -doped NIR-II luminescent nano-bioprobes. Although several classes of NIR-II luminescent probes like organic ...
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... and organic chromophore probe IR1061 with strong absorption at 800-1,100 nm were encapsulated in polycaprolactone. In the absence of H 2 O 2 , the 980 nm emission (I 980 ) of Er 3+ was suppressed due to the strong absorption of IR1061. Nevertheless, H 2 O 2 may induce the destruction of IR1061, and thus weaken its absorption from 800 to 1,100 nm (Fig. 10a). As a result, I 980 may gradually recover with increasing of the H 2 O 2 concentration. By contrast, the intensity of 1,180 nm emission (I 1180 ) of Ho 3+ was not affected by H 2 O 2 . Therefore, the concentration of H 2 O 2 can be quantified by determining the PL intensity ratio I 980 /I 1180 (Fig. 10b). As a proof-of-concept ...
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... weaken its absorption from 800 to 1,100 nm (Fig. 10a). As a result, I 980 may gradually recover with increasing of the H 2 O 2 concentration. By contrast, the intensity of 1,180 nm emission (I 1180 ) of Ho 3+ was not affected by H 2 O 2 . Therefore, the concentration of H 2 O 2 can be quantified by determining the PL intensity ratio I 980 /I 1180 (Fig. 10b). As a proof-of-concept experiment, they fabricated the microneedle patches based on the NaErF 4 :Ho@NaYF 4 NPs and IR1061 encapsulated polycaprolactone, which were applied for in vivo bioassay of H 2 O 2 in the inflammation site (Fig. 10c). By taking advantage of low autofluorescence of the NIR-II emission, the PL images of the ...
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... the concentration of H 2 O 2 can be quantified by determining the PL intensity ratio I 980 /I 1180 (Fig. 10b). As a proof-of-concept experiment, they fabricated the microneedle patches based on the NaErF 4 :Ho@NaYF 4 NPs and IR1061 encapsulated polycaprolactone, which were applied for in vivo bioassay of H 2 O 2 in the inflammation site (Fig. 10c). By taking advantage of low autofluorescence of the NIR-II emission, the PL images of the microneedle array can be clearly observed under the skin tissue of mice. Upon excitation at 1,530 nm, the PL signal of 1,180 nm was stable while the signal of 980 nm gradually increased as the evolution of inflammation with the continuous ...
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... taking advantage of low autofluorescence of the NIR-II emission, the PL images of the microneedle array can be clearly observed under the skin tissue of mice. Upon excitation at 1,530 nm, the PL signal of 1,180 nm was stable while the signal of 980 nm gradually increased as the evolution of inflammation with the continuous generation of H 2 O 2 (Fig. 10d). According to the linear correlation between H 2 O 2 concentration and log(I 980 /I 1180 ), the concentration deviation of H 2 O 2 in the inflammatory site can be monitored from 0 to 12 h, which provides a feasible strategy for the quantitative detection of disease markers in ...
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... at 790 nm. In their work, the integrated intensity ratio of Yb 3+ and Nd 3+ NIR-II emissions was found to decrease with the temperature from 10 to 50°C. A 4-fold higher sensitivity (0.44%/°C) was achieved than that of LaF 3 :Nd/Yb core-only NPs. Moreover, the proposed nanothermometer enabled monitoring of the real-time subcutaneous temperature (Fig. 11). After laserinduced heating, the subcutaneous temperature variation can be identified by the luminescent nanothermometry in a living animal (Fig. 11d) Cr/Nd NPs presented an outstanding sensitivity of 4.89%/°C, which was one order of magnitude higher than that of the vast majority of lu- minescent thermometers. However, the emission of ...
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... 50°C. A 4-fold higher sensitivity (0.44%/°C) was achieved than that of LaF 3 :Nd/Yb core-only NPs. Moreover, the proposed nanothermometer enabled monitoring of the real-time subcutaneous temperature (Fig. 11). After laserinduced heating, the subcutaneous temperature variation can be identified by the luminescent nanothermometry in a living animal (Fig. 11d) Cr/Nd NPs presented an outstanding sensitivity of 4.89%/°C, which was one order of magnitude higher than that of the vast majority of lu- minescent thermometers. However, the emission of Cr 3+ ions (820-840 nm) located in NIR-I region, which to some extent restricted their applications for temperature sensing in vivo. Very recently, ...
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... which to some extent restricted their applications for temperature sensing in vivo. Very recently, several interesting studies were reported by employing the hybrid structured nanothermometers for sensitive temperature sensing [119,[124][125][126][127]. Rodrí- guez et al. [119] designed a hybrid nanothermometer for subtissue temperature sensing (Fig. 12). This hybrid nanothermometer was prepared following a double-emulsion encapsulation procedure by PbS/CdS/ZnS QDs as temperature-sensitve response unit and temperature-insensitive NaGdF 4 :Nd as internal standard unit for the deep tissue ratiometric thermal sensing (Fig. 12b). The thermal sensitivity of the developed hybrid ...
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... [119] designed a hybrid nanothermometer for subtissue temperature sensing (Fig. 12). This hybrid nanothermometer was prepared following a double-emulsion encapsulation procedure by PbS/CdS/ZnS QDs as temperature-sensitve response unit and temperature-insensitive NaGdF 4 :Nd as internal standard unit for the deep tissue ratiometric thermal sensing (Fig. 12b). The thermal sensitivity of the developed hybrid nanostructures was determined to be 2.5%/°C, which was one order of magnitude higher than that of the available NIR-I nanothermometers [128,129]. Subsequently, Xu et al. [124] further improved the thermal sensitivity. Triplettriplet annihilation (TTA) dyad was modified on the surface of ...
Context 21
... was determined to be 2.5%/°C, which was one order of magnitude higher than that of the available NIR-I nanothermometers [128,129]. Subsequently, Xu et al. [124] further improved the thermal sensitivity. Triplettriplet annihilation (TTA) dyad was modified on the surface of NaYF 4 :Nd to design an organic/inorganic hybrid ratiometric thermometer (Fig. 13). The proposed organic/inorganic hybrid nanothermometer was applied to monitor the specific temperature variations and map the temperature distributions in the inflammatory mode, which exhibited high thermal sensitivity (~7.1%/°C) and resolution (~0.1°C). Nevertheless, the emission of TTA lay in the visible region, and double beam ...
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... to monitor the specific temperature variations and map the temperature distributions in the inflammatory mode, which exhibited high thermal sensitivity (~7.1%/°C) and resolution (~0.1°C). Nevertheless, the emission of TTA lay in the visible region, and double beam excitations combined with two detectors (PMT and InGaAs detectors) were required (Fig. 13a). In addition, different attenuation through tissue of the emission signal of 540 nm from TTA and 1,060 nm from NaYF 4 :Nd might deteriorate the measurement accuracy in vivo. NPs provide unique opportunities for simultaneous multiplexed assay of different disease markers in deep tissue. Last but not the least, the prevailing in vivo ...
Citations
... NIR-II emitting materials, including semiconductor quantum dots [16][17][18][19] , carbon nanotubes 20,21 , lanthanide-doped nanocrystals (LnNCs) [22][23][24][25][26] , and organic molecules [27][28][29][30][31] , have been developed for theranostic applications [32][33][34] . However, the efficient delivery of these nanoparticles to target the cellular structure of the bone remains challenging as the nanoparticles are typically filtered by the mononuclear phagocyte system, especially in the liver and spleen 35,36 , not to mention the slow blood flow and the high density of bone composites 37 . ...
Skeletal disorders are commonly diagnosed by X-ray imaging, but the radiation limits its use. Optical imaging through the near-infrared-II window (NIR-II, 1000–1700 nm) can penetrate deep tissues without radiation risk, but the targeting of contrast agent is non-specific. Here, we report that lanthanide-doped nanocrystals can passively target the bone marrow, which can be effective for over two months. We therefore develop the high-resolution NIR-II imaging method for bone disease diagnosis, including the 3D bone imaging instrumentation to show the intravital bone morphology. We demonstrate the monitoring of 1 mm bone defects with spatial resolution comparable to the X-ray imaging result. Moreover, NIR-II imaging can reveal the early onset inflammation as the synovitis in the early stage of rheumatoid arthritis, comparable to micro computed tomography (μCT) in diagnosis of osteoarthritis, including the symptoms of osteophyte and hyperostosis in the knee joint.
... More signi cantly, compared with the visible (400-700 nm) and NIR-I (700-900 nm) ranges, light excitation and emission at the NIR-II window (1000-1700 nm) can penetrate deep tissues, which allows high spatial and temporal resolutions to be achieved with high signal-to-background ratio (SBR), as the long wavelength of light leads to minimal tissue scatterings and auto uorescence [12][13][14][15] . Towards the realization of the above potentials, NIR-II emitting uorescent materials, including semiconductor quantum dots (QDs) [16][17][18][19] , carbon nanotubes 20,21 , lanthanide doped nanocrystals (LnNCs) [22][23][24][25][26] , and organic molecules [27][28][29][30][31] , have been developed for theranostic applications [32][33][34] . However, the e cient delivery of these nanoparticles to target the cellular structure of the bone remains challenging as the nanoparticles are typically ltered by the mononuclear phagocyte system, especially in the liver and spleen 35,36 , not mentioning the slow blood ow and the high density of bone composites 37 . ...
Bone health related skeletal disorders are commonly diagnosed by X-ray imaging, but the radiation limits its use. Light excitation and optical imaging through the near-infrared-II window (NIR-II, 1000–1700 nm) can penetrate deep tissues without radiation risk, but the targeting of contrast agent is non-specific. Here, we report that lanthanide-doped nanocrystals can be passively transported by endothelial cells and macrophages from the blood vessels into bone marrow microenvironment. We found that this bone targeting scheme can be effective for longer than two months. We therefore developed an intravital 3D and high-resolution planar imaging instrumentation for bone disease diagnosis. We demonstrated the regular monitoring of 1 mm bone defects for 11 days in NIR-II window, with spatial resolution similar to X-ray imaging result, but more flexible use in prognosis. Moreover, the passive targeting can be used to reveal the early onset inflammation at the joints as the synovitis in the early stage of rheumatoid arthritis. Furthermore, the proposed method is comparable to micro computed tomography (µCT) in recognizing symptoms of osteoarthritis, including the mild hyperostosis in femur which is ~ 100 µm thicker than normal, and the growth of millimeter-scale osteophyte in the knee joint, which further proves the power and universality of our approach.
... More significantly, compared with the visible (400-700 nm) and NIR-I (700-900 nm) ranges, light excitation and emission at the NIR-II window (1000-1700 nm) can penetrate deep tissues, which allows high spatial and temporal resolutions to be achieved with high signal-to-background ratio (SBR), as the long wavelength of light leads to minimal tissue scatterings and autofluorescence [12][13][14][15] . Towards the realization of the above potentials, NIR-II emitting fluorescent materials, including semiconductor quantum dots (QDs) [16][17][18] , carbon nanotubes 19,20 , lanthanide doped nanocrystals (LnNCs) [21][22][23][24][25] , and organic molecules [26][27][28][29][30] , have been developed for theranostic applications [31][32][33] . However, the efficient delivery of these nanoparticles to target the cellular structure of the bone remains challenging as the nanoparticles are typically filtered by the mononuclear phagocyte system, especially in the liver and spleen 34,35 , not mentioning the slow blood flow and the high density of bone composites 36 . ...
Bone health related skeletal disorders are commonly diagnosed by X-ray imaging, but the radiation limits its use. Light excitation and optical imaging through the near-infrared-II window (NIR-II, 1000-1700 nm) can penetrate deep tissues without radiation risk, but the targeting of contrast agent is non-specific. Here, we report that lanthanide-doped nanocrystals can be passively transported by endothelial cells and macrophages from the blood vessels into bone marrow microenvironment. We found that this passive targeting scheme can be effective for longer than two months. We therefore developed an intravital 3D and high-resolution planar imaging instrumentation for bone disease diagnosis. We demonstrated the regular monitoring of 1 mm bone defects for over 10 days, with resolution similar to X-ray imaging result, but more flexible use in prognosis. Moreover, the passive targeting can be used to reveal the early onset inflammation at the joints as the synovitis in the early stage of rheumatoid arthritis. Furthermore, the proposed method is comparable to {\mu}CT in recognizing symptoms of osteoarthritis, including the mild hyperostosis in femur which is ~100 {\mu}m thicker than normal, and the growth of millimeter-scale osteophyte in the knee joint, which further proves the power and universality of our approach in diagnosis of bone diseases
... [79] CJA also play an important role as chemical sensors [80] and shortwave infrared emitters, [81] and are widely used in biomedical applications, providing bright, biosafe organic chemicals for in vivo imaging. [29,60,81] In comparison to quantum dots, which are also widely used for NIR and SWIR bioimaging, [82] CJA present a safer option for in vivo imaging. Many quantum dots have high toxicity and their excretion from the body is also a drawback. ...
... Carbon nanotubes, [83] which are also widely used for NIR in vivo imaging, suffer from low quantum yields [84] and difficulties controlling their size distribution, which results in a broad absorption peak and low fluorescence. [83,85] Lanthanides are also intensively used in bioimaging, [82,86] since they present a narrow emission band and high photostability, but very few lanthanides have both an emission of about 1100 nm and high quantum yield. [82] For these reasons, CJA are a real bioimaging alternative to quantum dots, lanthanides and carbon nanotubes. ...
... [83,85] Lanthanides are also intensively used in bioimaging, [82,86] since they present a narrow emission band and high photostability, but very few lanthanides have both an emission of about 1100 nm and high quantum yield. [82] For these reasons, CJA are a real bioimaging alternative to quantum dots, lanthanides and carbon nanotubes. ...
Cyanines are one of the few kinds of molecules whose absorbance and emission can be shifted in a broad spectral range from the ultraviolet to the near infrared. They can easily transform into J‐aggregates with narrow absorption and emission peaks, along with a redshift in their spectra. This mini‐review presents cyanine dyes and their J‐aggregates and discusses their structure and spectral properties that illustrate their specificities. We summarize the theoretical and experimental state of the art on cyanine J‐aggregates and their applications, also laying the groundwork for cyanine J‐aggregates synthesis and characterization methods. Cyanines are a unique kind of molecules due to their broad spectral absorption and emission ranges, varied from the ultraviolet to the near infrared region. They can transform from monomers into J‐aggregates that exhibit narrow absorption and emission peaks, along with a bathochromic shift in their spectra. Future applications of cyanines vary from solar cells and chemical sensors to photodynamic therapy and medical diagnostics.
... 5,6 In particular, many efforts have been made to develop novel rare-earth (RE) ions-activated persistent luminescence materials with NIR-II emission because of their rich energy levels making their emissions cover the NIR-II spectral region. 7 For example, Pan et al. prepared Eu 2+ , Dy 3+ , and Er 3+ co-doped SrAl 2 O 4 persistent luminescence materials with NIR-II emission at 1530 nm by means of the persistent energy transfer (PET) between RE ions. 8 Furthermore, based on the PET from transition metal (TM) ions to RE ions, ZGGO:Cr 3+ ,Nd 3+ and ZGGO:Cr 3+ ,Er 3+ NIR-II persistent luminescence nanoparticles with emission at 1067 and 1530 nm were developed. ...
In this study, Zn2(1−x)Ni2xGa3Ge0.75O8 (x = 0.0002, 0.001, 0.002, 0.010, 0.020, and 0.030) nanoparticles with broadband NIR‐II emissions were synthesized by a hydrothermal synthesis combined with a vacuum annealing. For the Ni²⁺‐doped ZGGO samples (x = 0–0.03), with increasing concentration, the particle shape gradually becomes spherical and the average particle size decreases from 124.4 to 74.2 nm. Meanwhile, for the ZGGO:Ni²⁺0.01 nanoparticles, the asymmetrically broad emission peak around 1290 nm, which is the superposition of the two peaks locating at 1280 and 1450 nm, can be observed and the afterglow time exceeds 30 min. Based on the spectral data, luminescence decay curves, first‐principles calculations, and Tanabe–Sugano theory, it is found that Ni²⁺ ions can occupy not only tetrahedral but also octahedral Zn²⁺ sites (locating in anti‐site defects pair) in the spinel ZGGO host, and they have the contributions to the 1450 and 1280 nm emission peaks, respectively. Furthermore, the surface‐modified ZGGO:Ni²⁺ nanoparticles exhibited good stability in the H2O and HSA (5% human serum albumin, pH = 7.4) solutions and the occurred agglomeration sinking in the SLS (simulate lysosomal solution, pH = 4.7) solution. Compared to the narrow‐band NIR‐II emitting persistent luminescence nanoparticles (ZGGO:Cr³⁺,Er³⁺ and ZGGO:Cr³⁺,Nd³⁺), broadband NIR‐II emitting persistent luminescence nanoparticles (ZGGO:Ni²⁺ NIR‐II) possess stronger persistent luminescence intensity and can effectively avoid the water absorption of biological tissues. Our results suggest that ZGGO:Ni²⁺ persistent luminescence nanoparticles have a potential to become optical probes for deep‐tissue autofluorescence‐free bioimaging in the biomedical field.
... The applications of trivalent lanthanide (Ln 3+ )-doped inorganic luminescent nanoparticles (NPs) as deep-tissue-penetration fluorescent diagnostic and therapeutic agents have fascinated the broad research community in the past few years [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Taking advantage of the outstanding non-linear upconversion luminescence (UCL) and/or near-infrared (NIR) downshifting luminescence (DSL) of some given Ln 3+ ions like Er 3+ , these Ln 3+ -doped inorganic luminescent NPs enable deep-tissue NIR excitation and detection of fluorescence signal in vivo [15][16][17][18][19], bringing great opportunities to biomedical imaging with inherent merits like lower damage to the living organisms [20], minimal background interference [21], and hence much improved signal-to-background ratio compared with the other imaging modalities upon short-wavelength ultraviolet (UV) or visible light irradiation. ...
... October 2022 | Vol. 65 No.10 ...
Trivalent lanthanide (Ln3+)-doped luminescent nanoparticles (NPs) have been extensively investigated as deep-tissue-penetration visual bioimaging agents owing to their exceptional upconversion and near-infrared (NIR) luminescence upon irradiation of NIR light. However, in most cases, the power density of irradiation used for in vivo biological imaging is much higher than that of the reported maximum permissible exposure (MPE) value of NIR light, which inevitably does great damage to the living organisms under study and thus impedes the plausible clinical applications. Herein, by using a facile syringe pump-aided shell epitaxial growth method, we construct for the first time a new class of Ln3+-doped KMgF3:Yb/Er@KMgF3 core-shell NPs that can be activated by utilizing a 980-nm xenon lamp or diode laser with an ultralow excitation power density down to 0.08 mW cm−2, a value that is approximately 4 orders of magnitude lower than the MPE value set by the American National Standards Institute (ANSI) for safe bioimaging in vivo. By combining the comparative spectroscopic investigations with atomic-resolved spherical aberration corrected transmission electron microscopy (AC-TEM) characterization, we find that the reduced crystallographic defects are the primary cause underlying such an ultralow-power-excitable feature of the KMgF3: Yb/Er@KMgF3 core-shell NPs. And, by the same token, the resultant KMgF3:Yb/Er@KMgF3 core-shell NPs also exhibit an anomalous thermo-enhanced photoluminescence (PL) behavior coupled with an excellent photothermal stability that cannot occur in other Ln3+-doped core-shell NPs. These findings described here unambiguously pave a new way to prepare high-quality Ln3+-doped luminescent NPs with desirable ultralow-power-excitable capability and photothermal stability for future biomedical applications.
... In LnNCs, three components are commonly included: a host matrix, a sensitizer, and an activator [36][37][38][39][40][41][42]. The host material should meet the requirements of optical transparency and low lattice phonon energy. ...
... The activators with NIR-II emission mainly include Pr 3+ , Nd 3+ , Ho 3+ , Er 3+ , and Tm 3+ (Figure 3a,b) [36,41]. To overcome the weak light absorption problem of the activator ion itself, sensitizers with higher absorption coefficients are co-doped into the host, serving to harvest the excitation photons and transfer the excitation energy to activators, thus populating the radiative transition of activators for NIR-II luminescence. ...
... Finally, the excited state electrons return to the ground state and emit NIR-II luminescence ( Figure 3b). According to NIR-II emission of different activators, it can be roughly divided into three types of NIR-II probes [36,41,43,44]: (1) Er 3+ based NIR-II probes. NIR-II emission at intense 1525~1550 nm can be generated through 4 I13/2 → 4 I15/2 radiative transition. ...
Fluorescent bio/chemosensors are widely used in the field of biological research and medical diagnosis, with the advantages of non-invasiveness, high sensitivity, and good selectivity. In particular, luminescent bio/chemosensors, based on lanthanide nanocrystals (LnNCs) with a second near-infrared (NIR-II) emission, have attracted much attention, owing to greater penetration depth, aside from the merits of narrow emission band, abundant emission lines, and long lifetimes. In this review, NIR-II LnNCs-based bio/chemo sensors are summarized from the perspectives of the mechanisms of NIR-II luminescence, synthesis method of LnNCs, strategy of luminescence enhancement, sensing mechanism, and targeted bio/chemo category. Finally, the problems that exist in present LnNCs-based bio/chemosensors are discussed, and the future development trend is prospected.
... The combination of different types of rare earth ions (REI) in a single structure (single crystals, ceramics, glass ceramics, hybrid nanomaterials, etc.) represents a unique optical system, in which the luminescent properties can be tuned in a wide range by controlling the energy transfer between ions of different types through adjusting the composition and structure of the material. Such sophisticated optical systems can find applications in different fields, including ultrabroadband optical devices [1][2][3], microthermometry [4][5][6], bioimaging [7][8][9][10], and the production of light-emitting flexible materials [11][12][13]. ...
Optical materials doped with several lanthanides are unique in their properties and are widely used in various fields of science and technology. The study of these systems provides solutions for noncontact thermometry, bioimaging, sensing technology, and others. In this paper, we report on the demonstration of YVO4 nanoparticles doped with one, two, and three different rare earth ions (Tm3+, Er3+, and Nd3+). We discuss the morphology, structural properties, and luminescence behavior of particles. Luminescence decay kinetics reveal the energy transfer efficiency (up to 78%) for different ions under the selective excitation of individual ions. Thus, we found that the energy transition from Tm3+ is more favorable than from Er3+ while we did not observe any significant energy rearrangement in the samples under the excitation of Nd3+. The observed strong variation of REI lifetimes makes the suggested nanoparticles promising for luminescent labeling, anticounterfeiting, development of data storage systems, etc.
... To the best of our knowledge, a QY of 48.9% is the highest value among Er 3+ -activated NIR-IIb nanoparticles. 11 Long-Term NIR-IIb in Vivo Imaging of GI Tract in Mice. We developed a NIR-IIb ErNCs@GA contrast meal by mixing ErNCs with GA, as GA is a plant-derived viscosity-enhancing polysaccharide and has been widely used as the emulsifier. ...
... Stable rare earth (RE) ions with abundant emission peaks are promising candidates for FIR-based temperature sensing and luminescent materials [10][11][12]. The thermometer of RE-doped luminescent materials has superior performance, such as internal temperature sensing and photothermal therapy [13][14][15]. Er 3+ is notably acknowledged as an upconversion luminescent RE ion with two adjacent thermally coupled levels of 2 H 11/2 and 4 S 3/2 for thermometer function [16,17]. Other RE ions such as Pr 3+ , Yb 3+ , and Nd 3+ are also quite suitable for temperature sensing [18][19][20]. ...
Rare earth ions doped luminescent materials have drawn considerable attention as they can generate both upconversion and downshifting emissions. Here, the rare earth ions Pr³⁺/Er³⁺ codoped perovskite oxide Bi4Ti3O12 is proposed as a dual-mode temperature sensor and anti-counterfeiting material based on its up/down-conversion luminescence. Under 481 nm excitation, the intensity ratio of green emission (∼523 nm in Er³⁺) and red emission (∼611 nm in Pr³⁺) brings about a very high absolute sensitivity (Sa) of 2% K⁻¹ at 568 K and a maximum relative sensitivity (Sr) of 1.03% K⁻¹ at 478 K in the temperature range of 298–568 K. In addition, the upconversion green emissions of Er³⁺ yield a relatively-high Sr of 1.1% K⁻¹ at 298 K with 980 nm excitation, which can provide self-calibration coupled with down-conversion luminescence temperature sensing mode. Besides, this phosphor also shows tunable luminous colors for the potential application in the anti-counterfeiting field under various excitation wavelengths.
