Green Upconversion Luminescence Research Articles

Effects of Er3+ and Yb3+ concentrations on upconversion luminescence and thermal sensing characteristics of Sc2O3:Er3+/Yb3+ phosphors

Sc2O3:Er3+(x mol%)/Yb3+(3 mol%) (x = 0.3, 0.5, 0.7) and Sc2O3:Er3+(0.5 mol%)/Yb3+(y mol%) (y = 1, 3, 5) phosphors were synthesized by CO2 laser zone-melting method. The upconversion luminescence (UCL) spectra of Sc2O3:Er3+/Yb3+ fluorescent materials, which were pumped by 980 nm, were measured and analyzed. The results show that the UCL intensity reaches maxima when doped with 0.5 mol% Er3+ and 3 mol% Yb3+, and the increase of Yb3+ concentration leads to reduce the ratio of green UCL to red UCL. The temperature-dependent UCL spectra of Sc2O3:Er3+/Yb3+ fluorescent materials with various Er3+ and Yb3+ concentrations were measured from 290 K to 1023 K, and the thermal sensing characteristics were revealed via the fluorescence intensity ratio (FIR) technique. The maximal relative sensitivity (SR) are almost independent of the Er3+ and Yb3+ concentration, while the maximal absolute sensitivity (SA) increases with Yb3+ concentration in the whole measurement range. Among the prepared samples, the maxima of SA and SR are achieved for the sample of Sc2O3:Er3+(0.5 mol%)/Yb3+(5 mol%)，with the values of 5.34 × 10−3 K−1 (364.1 K) and 12.5 × 10−3 K−1 (290 K), respectively. Interestingly, for Sc2O3:Er3+ (0.5 mol%)/Yb3+ (3 mol%), having the highest UCL intensity, its maximum SA and SR are 4.90 × 10−3 K−1 (371.4 K) and 11.2 × 10−3 K−1 (290 K). The wide temperature sensing range and relatively high sensitivities of the fabricated materials provide excellent potential for temperature sensing.

Upconversion Luminescence Response of a Single YVO4:Yb, Er Particle.

We present the results of the luminescence response studies of a single YVO4:Yb, Er particle of 1-µm size. Yttrium vanadate nanoparticles are well-known for their low sensitivity to surface quenchers in water solutions which makes them of special interest for biological applications. First, YVO4:Yb, Er nanoparticles (in the size range from 0.05 µm up to 2 µm), using the hydrothermal method, were synthesized. Nanoparticles deposited and dried on a glass surface exhibited bright green upconversion luminescence. By means of an atomic-force microscope, a 60 × 60 µm2 square of a glass surface was cleaned from any noticeable contaminants (more than 10 nm in size) and a single particle of 1-µm size was selected and placed in the middle. Confocal microscopy revealed a significant difference between the collective luminescent response of an ensemble of synthesized nanoparticles (in the form of a dry powder) and that of a single particle. In particular, a pronounced polarization of the upconversion luminescence from a single particle was observed. Luminescence dependences on the laser power are quite different for the single particle and the large ensemble of nanoparticles as well. These facts attest to the notion that upconversion properties of single particles are highly individual. This implies that to use an upconversion particle as a single sensor of the local parameters of a medium, the additional studying and calibration of its individual photophysical properties are essential.

Upconversion nanoparticle-based fluorescence resonance energy transfer sensing platform for the detection of cathepsin B activity in vitro and in vivo.

A simple fluorescence resonance energy transfer (FRET) sensing platform (termed as USP), comprised of upconversion nanoparticles (UCNPs) as the energy donor and Cy5 as the energy acceptor, has been synthesized for cathepsin B (CTSB) activity detection in vitro and in vivo. When Cy5-modified peptide substrate (peptide-Cy5) of CTSB is covalently linked on the surface of UCNPs, the FRET between the UCNPs (excitation: 980nm; emission: 541nm/655nm) and Cy5 (excitation: 645nm) leads to a reduction in the red upconversion luminescence (UCL) signal intensity of UCNPs. Cy5 can be liberated from UCNPs in the presence of CTSB through the cleavage of peptide-Cy5 by CTSB, leading to the recovery of the red UCL signal of UCNPs. Because the green UCL signal of UCNPs remains constant during the CTSB digestion, it can be considered as an internal reference. The findings demonstrate the ability of USP to detect CTSB with the linear detection ranges of 1 to 100ng·mL-1 in buffer and 2 × 103 to 1 × 105 cells in 0.2mL cell lysates. The limits of detection (LODs) are 0.30ng·mL-1 in buffer and 887 cells in 0.2mL of cell lysates (S/N = 3). The viability of USP to detect CTSB activity in tumor-bearing mice is hasfurtherbeen investigated using in vivo fluorescent imaging.

Experimental optimization design synthesis and up-conversion luminescence properties of YNbO4:Ho3+/Yb3+

In order to obtain the maximum green up-conversion luminescence intensity of Ho3+/Yb3+ co-doped YNbO4, a uniform design and a quadratic general rotation combination design were applied to optimize the doping concentration. The concentration of the rare earth corresponding to the strongest green luminescence intensity was determined to be 10% Ho3+/34.9% Yb3+. Maximum luminous intensity of green light tested under 980 nm excitation was 157373.266, which was close to the theoretical calculated integral intensity value of 157290.825. The variation of the up-conversion luminescence spectra at different power density of the 980 nm laser was characterized. According to the formula fitting, the up-conversion luminescence process is a two-photon process. Meanwhile, the temperature sensing characteristic of the samples has been discussed. Finally, the CIE coordinates were analyzed and calculated to be (0.297, 0.692).

Enzyme-trigger ratiometric fluorescent nanoplatform for diagnosis and imaging of oral diseases

Oral health is an essential part of overall health. Matrix metalloproteinase-2 (MMP-2) is a potential biomarker for diseases. The ability to accurately detect MMP-2 in vivo and in vitro is of great importance for the early diagnosis and prognosis, as well as the treatment evaluation, of oral diseases. In this study, cyanine 3 (Cy3) polypeptide containing the specific peptide substrate (PLGVR) of MMP-2 was modified onto SiO2-coated upconversion nanoparticles to fabricate a fluorescence resonance energy transfer (FRET)-based ratiometric fluorescent nanoplatform (UCNPs@SiO2@Cy3-pep). The green upconversion luminescence of UCNPs@SiO2 is quenched by Cy3, while its red upconversion luminescence is undisturbed. After Cy3 is cleaved at the PLGVR peptide by MMP-2, it is detached from the surface of UCNPs@SiO2, resulting in the recovery of green luminescence. Based on this principle, we applied UCNPs@SiO2@Cy3-pep to detect MMP-2 activity in different oral disease samples and models. We found that the level of MMP-2 in saliva of patients with oral cancer was 10 times higher than that of healthy individuals. In addition, the MMP-2 level in patients with periodontitis and severe dental caries also increased to varying degrees compared with that in healthy patients. Finally, in vitro and in vivo imaging experiments revealed that the nanoplatform was effective in monitoring MMP-2 level. Together, the developed nanoplatform can be an ideal tool for medical diagnosis of MMP-2-related diseases.

Ratiometric upconversion nanoprobes for turn-on fluorescent detection of hypochlorous acid

Ratiometric fluorescent nanoprobes have been developed for the detection of hypochlorous acid (HOCl) by simply mixing upconversion nanocrystals (UCNCs) with plasmocorinth B (PB) dye molecules, where UCNCs are adopted as the energy donor and dye molecules are introduced as the energy acceptor. Specifically, green upconversion luminescence (UCL) emission of UCNCs can be effectively quenched by PB, resulting from the spectral overlap between the absorption of PB and UCL emission of UCNCs in the green region. Furthermore, owing to the electrostatic repulsion between negatively charged UCNCs and PB dye molecules, the fluorescence quenching mechanism is based on the IFE process. Upon interaction with HOCl, PB dye molecules degrade, resulting in the recovery of green UCL emission through inhibition of the IFE process. The red UCL emission, however, remains unchanged. Therefore, the red UCL emission is employed as an internal reference signal for the ratiometric detection of HOCl. The detection limit of the nanoprobe for HOCl is quantified to be 1.12 µM, which is much lower than that of colorimetric detection. Moreover, the developed sensor has been successfully applied for quantitative monitoring of HOCl in tap water.

Abnormal upconversion luminescence induced by defects and Er3+–Yb3+ distance change in Cs3GdGe3O9:Er3+/Yb3+ phosphors

AbstractA series of Er3+/Yb3+ co‐doped Cs3GdGe3O9 (CGG) phosphors were prepared by solid‐phase sintering method, and the microstructure and upconversion luminescence (UCL) properties were tested by variable‐temperature X‐ray diffractometry and variable‐temperature spectrometer. Abnormal UCL phenomena were found, which include UCL intensity continuously increasing under 980 nm laser continuous irradiation and UCL thermal enhancement. After 10 min of continuous irradiation by 980 nm laser at 513 K, the UCL intensity increased 2.91 times compared with the initial UCL intensity. The phenomenon is due to the electron releasing of host defects. The green UCL intensity of CGG:0.1Er3+/0.2Yb3+ decreases at 303–423 K and increases at 423–723 K, which reaches 13.23 times compared with that at 423 K. The phenomenon is due to Er3+–Yb3+ distance change by temperature and phonon‐assisted transitions. In addition, the absolute temperature sensitivities of samples are calculated by luminescence intensity ratio technology, the maximum absolute sensitivity of CGG:0.1Er3+/0.4Yb3+ is 0.00691 K−1 at 546 K, and the maximum relative sensitivity of CGG:0.1Er3+/0.1Yb3+ is 0.01224 K−1 at 303 K. These results indicate that CGG:Er3+/Yb3+ phosphors can be used as a high‐temperature optical thermometer.

Synthesis and luminescence properties of Er3+-Yb3+ doped glass ceramics with tridymite structure

By melt annealing technique, Er3+-Yb3+ co-doped precursor glass (PG) was prepared. Glass ceramics (GCs) containing KZnPO4 crystal phase with tridymite structure were obtained by heat treatment of PG. The optimum heat treatment conditions of GCs are 670 °C for 60 min. Under these conditions, the average grain size of GC is about 205 nm, and the light transmittance in the visible region is about 80%. Through the analysis of the Rietveld refinement results of XRD, the lattice constants a and b of KZnPO4 crystal decreased from 18.155 Å to 18.109 Å, and c decreased from 8.504 Å to 8.451 Å. Therefore, it is inferred that Er3+ and Yb3+ replace the Zn2+ in the lattice. The green up-conversion luminescence of GC is about 10 times that of PG excited by 980 nm laser. The optimal doping concentrations of Er3+ and Yb3+ in GCs are 0.5% and 1.0%, respectively. The calculation results of chromaticity coordinates show that Er3+-Yb3+ co-doped GCs with KZnPO4 crystal phase is a promising green up-conversion luminescent material.

Multi-Mode Lanthanide-Doped Ratiometric Luminescent Nanothermometer for Near-Infrared Imaging within Biological Windows

Owing to its high reliability and accuracy, the ratiometric luminescent thermometer can provide non-contact and fast temperature measurements. In particular, the nanomaterials doped with lanthanide ions can achieve multi-mode luminescence and temperature measurement by modifying the type of doped ions and excitation light source. The better penetration of the near-infrared (NIR) photons can assist bio-imaging and replace thermal vision cameras for photothermal imaging. In this work, we prepared core-shell cubic phase nanomaterials doped with lanthanide ions, with Ba2LuF7 doped with Er3+/Yb3+/Nd3+ as the core and Ba2LaF7 as the coating shell. The nanoparticles were designed according to the passivation layer to reduce the surface energy loss and enhance the emission intensity. Green upconversion luminescence can be observed under both 980 nm and 808 nm excitation. A single and strong emission band can be obtained under 980 nm excitation, while abundant and weak emission bands appear under 808 nm excitation. Meanwhile, multi-mode ratiometric optical thermometers were achieved by selecting different emission peaks in the NIR window under 808 nm excitation for non-contact temperature measurement at different tissue depths. The results suggest that our core-shell NIR nanoparticles can be used to assist bio-imaging and record temperature for biomedicine.

Excellent upconversion luminescence intensity in Er3+/Yb3+/Mo4+ triple-doped BiTa7O19 phosphors

BiTa7O19:Er3+/Yb3+/Mo4+ phosphors with excellent upconversion luminescence (UCL) intensity were synthesized by high temperature solid state method. The crystal structure, grain morphology and valence states of molybdenum ions were determined by X-ray diffraction (XRD), field emission scan electronic microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) technologies, respectively, and the UCL properties were studied by spectroscopy under 980 nm laser excitation. The green UCL intensity of BiTa7O19:0.1Er3+/0.4Yb3+/0.4Mo4+ is 1.66 times higher than that of commercial NaYF4:Er3+/Yb3+ under 980 nm laser excitation with 18.09 W/cm2. The UCL intensity of BiTa7O19:Er3+/Yb3+ phosphors increased first and then decreased with the increase of 980 nm laser excitation power density (0.38–56.69 W/cm2), while the UCL intensity of BiTa7O19:Er3+/Yb3+/Mo4+ phosphors can keep increasing with the increase of excitation power density. Based upon the luminescence intensity ratio (LIR) technique, the maximum absolute sensitivity (SA) is 0.01046 K−1 at 401 K. The experiment proved that BiTa7O19:Er3+/Yb3+/Mo4+ phosphors had strong acid and alkali resistance compared with NaYF4:Er3+/Yb3+. It indicates that BiTa7O19:Er3+/Yb3+/Mo4+ can replace NaYF4:Er3+/Yb3+ to be applied as luminescence imaging and temperature sensors in complex environments under high 980 nm laser excitation power density.

Dual-resonance enhancement upconversion luminescence by elongated Ag semi-shell coated on NaYF4:Yb,Er@SiO2 nanorod

Plasmonic resonance induced by metallic structures is a feasible solution to enhance the upconversion luminescence (UCL) of lanthanide-doped nanocrystals. A simulation investigation on the optical properties of an elongated Ag semi-shell coated on nanorod is carried out in this paper. Nondegenerate longitudinal and radial void modes in the Ag cavity can be tuned almost independently and controllably to resonate with excitation and emission simultaneously via adjusting the length and diameter of the nanorod respectively. Moreover, both mode volumes are concentrated in the central region of the cavity. Spectral-plus spatial-overlapping ensures that the elongated Ag semi-shell is an efficient dual-resonance enhancement plasmonic structure. Under dual-resonance conditions, green UCL can achieve 718-fold enhancement when radial resonance overlapping with green UCL, while red UCL can achieve 141-fold enhancement when overlapping with red UCL, with original quantum efficiency (η0) of 1%, both values are higher than that of gold nanorod. Since Purcell effect, resonating with different emission bands can realize color modulation, the intensity ratio of green UCL to red can raise to 9.1 or lower to 1.1 from the original 2.0. Although enhancement gradually weakens with the increase of η0, more than 20-fold enhancement can be still obtained even with η0 up to 33%.

Two‐wavelength excitation–driven robust operation of green up‐conversion emission in Er3+‐doped oxyfluoride glass–ceramic

AbstractEfficient optical modulation enables a significant improvement of optical conversion efficiency and regulation of optical response rate, showing great potential for optoelectronics applications. However, the weak interaction between photons poses a strong obstacle for manipulating photon–photon interactivity. Here, upon simultaneous excitation of 850 and 1550 nm, a fast–slow optical modulation of green up‐conversion (UC) luminescence in oxyfluoride glass ceramics containing NaYF4:Er3+ nanocrystals can be achieved. Compared with the sum of luminescence intensity excited by the two single‐wavelengths, green UC luminescence excited by simultaneous two‐wavelength presents an obvious increase by approximate six times. Interestingly, the response rate of green UC luminescence relies on the pump strategy of two‐wavelength excitation, showing as high as two times of the fast–slow response difference. The fast–slow optical modulation of green UC luminescence under two‐wavelength excitation is promising for emerging applications in all‐optical switching.

Paper-based LRET sensor for the detection of total heavy rare-earth ions.

Based on the mechanism of luminescence resonance energy transfer (LRET) and using a special single strand DNA as the recognition element, a portable paper-based sensor for the accurate detection of total heavy rare-earth ions (mainly Gd3+, Tb3+ and Dy3+) concentration was proposed. The RNA cleaving-DNAzyme should recognize rare-earth ions to cleave RNA on DNA duplexes linking UCNPs and AuNPs, causing UCNPs and AuNPs to approach each other, inducing LRET, which attenuated the green upconversion luminescence (UCL) triggered by the 980 nm laser. UCL was captured by a charge-coupled device (CCD) image sensor and processed with the red-green-blue (RGB) image to quantitatively analyze heavy rare-earth ions in the samples. In the range of 5–50 μmol·L-1, the sensor has good sensitivity, with the limit of detection of 1.26 μmol L−1.

Multifunctional CaF2: Yb3+, Ho3+, Gd3+ Nanocrystals: Insight into Crystal Growth and Properties of Upconversion Luminescence, Magnetic, and Temperature Sensing Properties.

The upconversion (UC) emission intensity of Ln3+-doped CaF2 nanomaterials is not ideal, which limits their application in some advanced scientific fields. Hence, it is extremely imperative to enhance the emission intensity of UC nanocrystals. In this work, an ionic-liquid-assisted hydrothermal method based on an ethylene glycol (EG) and ionic liquid (IL) two-phase system was used to synthesize CaF2 doped with Yb3+ and Ho3+. The influence of the amount of IL and the reaction time as well as the concentration of Gd3+ doping on morphology and size was studied in detail, and the growth mechanism was proposed. Green UC luminescence materials were obtained through co-doping Yb3+ and Ho3+ ions. Furthermore, the luminescence of UC was increased monotonically with the introduction of Gd3+ ions. The effect mechanism of Gd3+ doping on the UC luminescence was put forward, which might provide a new method for the promotion of UC luminescence. In addition, the temperature sensing of CaF2: Yb3+/Ho3+/Gd3+ was investigated, which demonstrated that the phosphor has a potential application prospect in thermal sensing. Meanwhile, CaF2: Yb3+/Ho3+/Gd3+ also exhibited a paramagnetic property at room temperature. Therefore, these multifunctional nanocrystals may have prospective applications in optical bioimaging, magnetic resonance imaging, and temperature sensing.

Upconversion luminescence thermal enhancement and emission color modulation of LiYGeO4:Er3+/Yb3+ phosphors

A series of LiYGeO4:Er3+/Yb3+ phosphors were synthesized by solid-phase sintering method, and the upconversion luminescence (UCL) thermal enhancement and emission color modulation were investigated under 980 and 1550 nm laser excitations. When Er3+ doping concentration is kept at 0.02, the UCL intensity reaches the maximum at the Yb3+ doping concentration with 0.20. With temperature increasing from 303 to 723 K, the green UCL intensities of samples reach maximum enhancement as high as 4.56 and 11.54 times under 980 and 1550 nm laser excitations, respectively. The optical temperature sensing performance of these samples was evaluated by luminescence intensity ratio (LIR) technology, and the maximum absolute sensitivities in LiYGeO4:0.02Er3+/0.40Yb3+ are 0.01020 K−1 at 625 K and 0.01026 K−1 at 655 K under 980 and 1550 nm laser excitations, respectively. In addition, the modulation of UCL color can be realized by changing laser excitation power, temperature and excitation wavelength. These results show that LiYGeO4:Er3+/Yb3+ phosphors can be used as high-temperature optical thermometer and anti-counterfeiting.

Designing and temperature sensing characteristics of upconversion luminescence core-shell structures with negative and positive thermal expansion

Generally, lanthanum ions doped positive expansion and negative expansion materials exhibit thermal quenching and enhancement of upconversion luminescence (UCL), respectively. Combining the UCL characteristics of positive expansion and negative expansion lattices is of importance for developing efficient temperature sensing systems. Here, positive expansion TiO 2 :Yb 3+ , Er 3+ three dimensionally ordered macroporous film was prepared by the template-assisted approach, and the Yb 2 W 3 O 12 : Er 3+ solution was filled into the TiO 2 : Yb 3+ , Er 3+ three dimensionally ordered macroporous film. After secondary sintering, the shell of negative expansion Yb 2 W 3 O 12 : Er 3+ was formed on the surface of TiO 2 :Yb 3+ /Er 3+ core. Under 980 nm excitation, the red and green UCL is predominate for the spectra of TiO 2 :Yb 3+ /Er 3+ core and Yb 2 W 3 O 12 : Er 3+ shell, respectively. With the measurement temperature increasing, the green UCL from negative expansion Yb 2 W 3 O 12 : Er 3+ shell increases, while the red UCL from positive expansion TiO 2 :Yb 3+ , Er 3+ core decreases. The performance of temperature sensing was characterized by the monitoring the UCL intensity ratio between 525 nm and 660 nm. The temperature sensitivity is about 1.12% K −1 , which is larger than that of thermally coupled FIR technology. We believed that the present work is instructive for developing new generation temperature sensor.

Intense red up-conversion luminescence and temperature sensing property of Yb3+/Er3+ co-doped BaGd2O4 phosphors

In this study, intense red and extremely weak green up-conversion (UC) luminescence was obtained in BaGd2O4: x mol% Yb3+/y mol% Er3+ phosphors under the excitations of 980 nm and 1550 nm. The corresponding maximum integrated intensity ratios of the red to green UC emissions are 50.3 and 158.7, respectively. The UC luminescence mechanisms upon different excitations were discussed. It was confirmed that two-photon and three-photon processes were responsible for both the red and green UC emissions excited at 980 nm and 1550 nm, respectively. The energy transfer efficiency from Er3+ to Yb3+ was calculated according to the fluorescence lifetime measurement under 1550 nm excitation. Temperature sensing based upon the thermally coupled energy levels 2H11/2/4S3/2 as well as thermally coupled Stark sublevels of 4F9/2 level of Er3+ was investigated under the excitation of 980 nm. The maximum absolute sensitivities were respectively obtained to be 0.42% K−1 at 573 K and 0.18% K−1 at 298 K. Our results indicated that BaGd2O4: Yb3+/Er3+ phosphors might be a kind of promising red UC phosphors with optical temperature measurement function.

Multimode Anticounterfeiting Labels Based on a Flexible and Water-Resistant NaGdF4Yb3+,Er3+@Carbon Dots Chiral Fluorescent Cellulose Film.

Advanced fluorescent anticounterfeiting technology has attracted a great deal of attention and inspired researchers to develop reliable fluorescent materials with multimodal luminescence. Herein, hydrophobic NaGdF4:Yb3+,Er3+ nanoparticles with dual-mode luminescence were prepared through a one-step solvothermal method using oleic acid as a chelating agent and octadecene as a solvent. The as-synthesized sample was found to provide both green upconversion luminescence and blue downconversion luminescence at excitation wavelengths of 365 and 980 nm. The structure and composition analysis showed that the as-obtained samples were spherical NaGdF4:Yb3+,Er3+@carbon dots (CDs) with a 14.5 ± 0.2 nm particle size and good dispersity in nonpolar solvents. Subsequently, NaGdF4:Yb3+,Er3+@CDs were coated on a cholesteric nanocellulose film with structural color to prepare multimode circularly polarized fluorescent materials. The prepared composite film is flexible and water-resistant, meaning that it is very suitable for anticounterfeiting labels, not only providing a simple and rapid synthesis method with which to prepare multimode fluorescent materials but also presenting a novel anticounterfeiting technology.

Green Up-Conversion Luminescence in Yb/Er Co-Doped AlN Thin Film by RF Magnetron Sputtering

In this research study, aluminum Nitride (AlN) thin film co-doped with erbium and ytterbium has been deposited on Si (100) substrate by RF magnetron Sputtering. After deposition, the film was annealed at 1100 °C in ambient conditions. It’s structural properties were investigated X-ray diffraction (XRD). Thin films morphology is studied using SEM, and EDX provides the chemical composition information. The photoluminescence property of deposited film was investigated by FS5 spectrofluorometer. XRD result revealed that the film has grown along the c-axis oriented in hexagonal wurtzite structure. SEM Result shows that the average size of the particle is 100 nm. The up-conversion luminescence showed intense green and red emission peaks at 530 nm, 552 nm, and 665 nm due to the transition of Er (2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2) with excitation of 984 nm. The excitation wavelength with 483 nm photons produces visible luminescence in the green and red region with 557 and 660 nm due to Erbium.

Ratiometrically pH-Insensitive Upconversion Nanoprobe: Toward Simultaneously Quantifying Organellar Calcium and Chloride and Understanding the Interaction of the Two Ions in Lysosome Function.

Calcium and chloride levels are closely related to lysosome dysfunction. However, the simultaneous measurement of calcium (Ca2+) and chloride (Cl-) in acidic subcellular organelles, which is conducive to a deep understanding of lysosome-related biological events, remains a challenge. In this study, we developed a pH-insensitive, ratiometric NIR nanoprobe for the simultaneous detection of Ca2+ and Cl- in acidic lysosomes and determined the roles of the two ions in lysosome function. The upconversion nanoprobe with blue, green, and red emissions was modified with a Ca2+-sensitive dye (Rhod-5N) and Cl--responsive fluorophore (10,10'-bis[3-carboxypropyl]-9,9'-biacridinium dinitrate, BAC). As a result of a dual-luminescence resonance energy transfer between upconversion nanoparticles (UCNPs) and Rhod-5N/BAC, the blue and green upconversion luminescence (UCL) of UCNPs were quenched and the red UCL was used as the reference signal. The ratiometric upconversion nanoprobe possesses a specific ability for the concurrent recognition of Ca2+ and Cl- ions independent of the influence of the environmental pH. To locate the probe in the lysosome, dextran was further modified with upconversion nanoparticles. Then, the nanoprobe with a high spatial resolution was constructed for the simultaneous monitoring of Ca2+ and Cl- in acidic lysosomes. Moreover, it was found that the reduction of lysosomal Cl- affects the release of lysosomal Ca2+, which further blocks the activities of specific lysosomal enzymes. The ratiometric NIR nanoprobe has great potential for decoding and evaluating lysosomal diseases.