Down-conversion Fluorescence Research Articles

A colorimetric/down-conversion fluorescence dual-readout probe for the recognition of Cu2+ and its application in environmental water by single PEI@NaYF4: Eu3+ nanoparticles

The pollution caused by heavy metals like Cu2+ remains a pressing issue, as the release of Cu2+-laden sewage can lead to detrimental effects on both soil ecosystems and human well-being. Herein, a novel colorimetric and down-conversion fluorescence probe, i.e. PEI@NaYF4: Eu3+ NPs, for selective and sensitive detection of Cu2+ with colorimetric and down-conversion fluorescence dual signal changes was reported. Such dual-signal detection mode offers enhanced sensitivity, accuracy, and cost-effectiveness in detecting Cu2+. The probe with spherical shape and excellent monodispersity was synthesized by a high temperature reflux method. The PEI moiety of the NPs is chosen due to the ability to chelate Cu2+ forming copper amine complexes. Such a unique feature is invoked to develop a versatile detection platform for the colorimetric detection of Cu2+ ions. In the presence of Cu2+, the visual color of probe in solution changes from colorless to blue with a low detection limit of 100 nM without any assistance of equipment. The probe emits down-conversion fluorescence with two main typical emission peaks centered at 592 and 614 nm under an excitation of 394 nm. The copper amine complexes formed by the combination of Cu2+ and the PEI moiety of the NPs quench down-conversion fluorescence by an internal filtration effect. Probe shows a specific on–off response to Cu2+ in aqueous solution with nanomolar LOD, fast response, and good selectivity, and without interference by a range of metal ions. A practical application shows that PEI@NaYF4: Eu3+ NPs have good recovery ranges of 96–105 % for Cu2+ detection in real environment water samples from different locations. This strategy proves that a colorimetric and down-conversion fluorescence probe is a potential tool for addressing heavy metal ions-induced water pollution.

Rare Earth Nanoprobes for Targeted Delineation of Triple Negative Breast Cancer and Enhancement of Radioimmunotherapy.

Radiotherapy demonstrates a synergistic effect with immunotherapy by inducing a transformation of "immune cold" tumors into "immune hot" tumors in triple negative breast cancer (TNBC). Nevertheless, the effectiveness of immunotherapy is constrained by low expression of tumor-exposed antigens, inadequate inflammation, and insufficient tumor infiltrating lymphocyte (TILs). To address this predicament, novel lutecium-based rare earth nanoparticles (RENPs) are synthesized with the aim of amplifying radiation effect and tumor immune response. The nanoprobe is characterized by neodymium-based down-conversion fluorescence, demonstrating robust photostability, biocompatibility, and targetability. The conjugation of RENPs with a CXCR4 targeted drug enables precise delineation of breast tumors using a near-infrared imaging system and improves radiation efficacy via lutetium-based radio-sensitizer invivo. Furthermore, the study shows a notable enhancement of immune response through the induction of immunogenic cell death and recruitment of TILs, resulting in the inhibition of tumor progression both invitro and invivo models following the administration of nanoparticles. Hence, the novel multifunctional nanoprobes incorporating various lanthanide elements offer the potential for imaging-guided tumor delineation, radio-sensitization, and immune activation post-radiation, thus presenting an efficient radio-immunotherapeutic approach for TNBC.

Comparing Pr3+ and Nd3+ for deactivating the Er3+: 4I13/2 level in lanthanum titanate glass

Erbium lanthanum titanate glasses were prepared by levitation melting for the spectroscopic study of ways to promote the mid-infrared fluorescence. Two series of heavily erbium doped glasses (15 wt%) were prepared with the addition of either Pr3+ or Nd3+ in amounts relative to Er3+ of 0.05, 0.1, and 0.2. Both ions quench the lower Er3+ laser level with the Pr3+ doing so more rapidly. Although high co-dopant concentrations result in higher energy transfer, as clearly evidenced in upconversion and downconversion fluorescence measurements, the mid-infrared lifetime also suffers a reduction and, therefore, a balance must be struck in the co-dopant concentration. Lifetime and spectral measurements indicate that, at a fixed relative co-dopant amount, Pr3+ is more effective than Nd3+ at removing the bottleneck of the Er3+ 4I13/2 level. Moreover, consideration of the lifetimes alongside the absorption data of the individual ions indicates that despite the large absorption cross-section of Nd3+ at 808 nm, the concentration needed to yield more absorbed power than utilizing direct 976 nm excitation of Er3+ results in unfavorable lifetimes of the mid-infrared transition. In the end, Pr3+ prevails as the superior co-dopant in terms of the effects on fluorescence lifetimes as well as potential laser system design considerations. In a unique self-doping approach, a reducing melt atmosphere of Ar instead of O2 creates a small fraction of Ti3+. In 5Er2O3-12La2O3-83TiO2 glass, the presence of Ti3+ quenches the 4I13/2 emission about 2.6 times more than the 4I11/2 when lifetimes are compared to an O2 melt environment. As an additional means of increasing the mid-infrared emission, the effect of temperature on the mid- and near- infrared lifetimes of a lightly doped lanthanum titanate composition is investigated between 77-300 K. The mid-infrared lifetime increases by ∼30% while the near-infrared lifetime increases by ∼10%, which suggests in addition to co-doping, active cooling of the gain media will further enhance performance.

Porphyrin-Sensitizers and Anthracene-Annihilators Built in Isostructural Frameworks for Investigating Triplet-Triplet Annihilation Upconversion.

In this study, four isostructural pillar-layered frameworks were constructed using a porphyrin layer and an anthracene pillar, which served as the sensitizer and annihilator, respectively, in the triplet-triplet annihilation upconversion (TTA-UC) system. Framework 1 demonstrated the highest upconversion quantum yield of 1.01%. Additionally, 1 and 2 also exhibited down-conversion fluorescence resulting from the porphyrin component. A twist intramolecular charge transfer (TICT) state was observed in the bianthracene chromophore of 2, resulting in transient rotation of two anthracene rings and red-shifted emission. Both computational studies and experiments confirmed the transition from a locally excited state to a TICT state upon the inclusion of polar guest molecules into the framework.

Dual-mode photoluminescent microspheres with silica core, separator layer and envelope for anti-counterfeiting ink

The microsphere is concentrically constructed on the basis of SiO2 nanocore on which Gd2O3:Yb,Er upconversion luminescent layer, SiO2 separator, Gd2O3:Ln@SiO2 (Ln3+ = Tb3+, Eu3+) downconversion luminescent layer, and SiO2 envelope are successively deposited by means of wet chemistry method. Under 980 nm near-infrared laser excitation, the microspheres emit bright upconverted green light due to Gd2O3:Yb,Er luminescent layer. While, under 254 nm portable ultraviolet lamp irradiation, they produce red and green downconversion fluorescence because of Gd2O3:Ln (Ln3+ = Tb3+ or Eu3+) luminescent layer. The silica core fixes the luminescence center, reduces non radiative transitions caused by molecular vibration, enhances fluorescence intensity, and saves rare earth resources. Impressively, the silica separator layer isolates the upconversion luminescence of Er3+ and downconversion of Eu3+, preventing cross relaxation and quenching of Er3+ fluorescence. The silica envelope plays a crucial role in the photoluminescence of the prepared microspheres. The photoluminescence quantum yield of the microspheres initially increases from 90.4 % to 95.9 % and then decreases to 82.9 % as the thickness of SiO2 layer on the ∼3 nm-thick Gd2O3:Ln shell rises from 3 nm to 16 nm. The absorption of photons reaches its maximum when the SiO2 layer is 8 nm thick. This thickness corresponds to the lowest rate constant for non-radiative transitions. The proto inks prepared from the dual-mode microspheres exhibit good performance including good luminescence and high dispersibility for practical anti-counterfeiting applications.

Long afterglow particle enables spectral and temporal light management to boost photosynthetic efficiency

Herein, we develop a strategy of matched spectral and temporal light management to improve photosynthetic efficiency by co-assembling natural thylakoid membrane (TM) with artificial long afterglow particle (LAP). To be specific, LAP with excellent stability and biocompatibility possesses the capabilities of light conversion and storage, optically-matched with the absorption of TM. These favorable features permit LAP as an additional well-functioned light source of photosynthesis performed by TM. As a consequence, enhanced photosynthesis is achieved after co-assembly, compared with pure TM. Under light, the rates of electron transfer, oxygen yield and adenosine triphosphate (ATP) production in this biohybrid architecture are boosted owing to down-conversion fluorescence emission from LAP. Under dark, persistent phosphorescence emission in charged LAP facilitates continual photosynthesis of TM, while that of pure TM almost stops immediately. This proof-of-concept work opens a new route to augment the photosynthetic efficiency of green plants by utilizing precise light-managed materials.

A smartphone-assisted down/up-conversion dual-mode ratiometric fluorescence sensor for visual detection of mercury ions and l-penicillamine

Establishment of a rapid, sensitive, visual, accurate and low-cost fluorescence detection system to detect multiple targets was of great significance in food safety evaluation, ecological environment monitoring and human health monitoring. In this work, a smartphone-assisted down/up-conversion dual-mode ratiometric fluorescence sensor was proposed based on metal-organic framework (NH2-MIL-101(Fe)) and CdTe quantum dots (CdTe QDs) for visual detection of mercury ions (Hg2+) and L-penicillamine (L-PA), in which NH2-MIL-101(Fe) was used as the reference signal and CdTe QDs was used as the response signal. The down-conversion fluorescence system at excitation wavelength of 300 nm (ex: 330 nm) was used to detect Hg2+ and L-PA, in which the detection limit of Hg2+ was 0.053 nM with the fluorescence color changed from green to blue, and the detection limit of L-PA was 1.10 nM with the fluorescence color changed from blue to green. Meanwhile, the up-conversion fluorescence system at excitation wavelength of 700 nm (ex: 700 nm) was used to detect Hg2+ and L-PA. The detection limits of Hg2+ and L-PA were 0.11 nM and 2.93 nM, respectively. The detection of Hg2+ and L-PA were also carried out based on the color extraction RGB values identified by the smartphone with a detection limit of 0.091 nM for Hg2+ and 8.97 nM for L-PA. In addition, the concentrations of Hg2+ and L-PA were evaluated by three-dimensional dynamic analysis in complex environments. The smartphone-assisted down/up-conversion dual-mode ratiometric fluorescence sensor system provides a new strategy for detection Hg2+ and L-PA in food safety evaluation, environmental monitoring and human health monitoring.

Effect of annealing temperature on optical properties of Erbium doped Y2Zr2O7 transparent ceramics

Through the vacuum sintering method, Erbium-doped Y2Zr2O7 transparent ceramics were successfully fabricated. The obtained ceramics were annealed at different temperatures and the relationship between annealing temperature and sample structure was investigated to reveal the effect of oxygen vacancy. Y1.98Er0.02Zr2O7 ceramics annealed at 800 °C starts to be transparent and when added up to 900 °C, samples show the highest transmittance over 76% in the near-infrared (NIR) region. Then the transmittance gradually decreased to 71% with the increase of annealing temperature. XRD and SEM measurements were performed to characterize the crystal structure and microstructure of Er3+: Y2Zr2O7 as-prepared powders and ceramics. The excitation spectra display that Y1.98Er0.02Zr2O7 ceramics can be effectively excited by 382 nm. When the annealing temperature exceeds 700 °C, two strong green emission bands and one red emission band can be observed in both up-conversion (UC) and down-conversion (DC) fluorescence spectra. Our results suggest that annealing temperature has a great impact on the structure and optical properties of Er3+: Y2Zr2O7 ceramics, which is significant for fabricating ceramics with better optical properties.

One-pot hydrothermal synthesis of Si-doped carbon quantum dots with up-conversion fluorescence as fluorescent probes for dual-readout detection of berberine hydrochloride

Here, the high fluorescent silicon-doped carbon quantum dots (Si-CQDs) were prepared by a facile and one-pot hydrothermal assay using 3-aminopropyltrimethoxysilane as the carbon and silicon source. The prepared Si-CQDs exhibit favorable water-soluble, high-temperature resistance, acid resistance, alkali resistance, high ionic strength resistance, high photostability, film-forming ability and solid-state fluorescence. Compared to other Si-CQDs that have been reported, the prepared Si-CQDs show unique up-conversion fluorescence. Furthermore, it is found that berberine hydrochloride (BH) can effectively quench the down- and up-conversion fluorescence of the Si-CQDs, making it can be used as a highly sensitive and specific probe for BH dual-mode sensing. Meanwhile, the linear range of down-conversion fluorescence detection for BH is 0.5-30.0 µmol/L with a limit of detection (LOD) of 50 nmol/L, and the linear range of up-conversion fluorescence assay for BH is 0-25.0 µmol/L. The mechanism of down-conversion fluorescence quenching by BH was investigated through a series of studies. The results show the quenching mechanism is the inner filter effect (IFE). Moreover, this proposed strategy has been well used to analyze BH in urine samples with satisfactory results.

Up-/Downconversion Fluorescence Dual-Channel Probe Based on NaYF4: Yb/Er/Eu Nanoparticles for the Determination of Cu(II)

Copper ions [Cu(II)] are essential in many biological processes. Accurate determination of Cu(II) is of great significance for environment monitoring and diseases diagnosis. A dual-channel probe (DCP) with up/downconversion fluorescence is developed using a one-pot solvothermal method in this work. Yb(III), Er(III), and Eu(III) are doped into NaYF4 capped with ethylene imine polymer (PEI), that is, PEI-capped NaYF4: Yb(III), Er(III), and Eu(III) NPs (marked as PEI-capped NYF: Yb/Er/Eu NPs), forming the DCP to determine Cu(II) through the up- and downconversion fluorescence variations. The DCP is designed aiming to minimize mutual interference between the fluorescent signals. Under the optimized conditions, the up-/downconversion fluorescence performances of DCP are excellent, including a linear range for 30 nM–10 μM Cu(II) with the detection limits of 29.30, 18.23, and 26.04 nM (monitoring wavelengths of 545, 592, and 616 nm) as well as excellent selectivity to Cu(II). The mechanism of Cu(II) determination could be attributed to the quenching of up-/downconversion fluorescence because of the inner filter effect triggered by PEI–Cu(II) complexes. To illustrate the potential application of up-/downconversion fluorescence DCP, the concentration of Cu(II) in tap water is detected, and satisfactory results are acquired, indicating that the up-/downconversion fluorescence DCP has promising applications in the fields of food safety and environmental detection. More importantly, the proposed design idea is universal regarding the construction of other dual-channel probes for the detection of metal ions.

Hot-Band Absorption of a Cationic RNA Probe Enables Visualization of ΔΨm via the Controllable Anti-Stokes Shift Emission

Mitochondrial membrane potential (ΔΨm) is an important biophysical parameter playing central roles in cell apoptosis, mitochondrial dysfunction, and other biological and pathological processes. Herein, we have rationally designed and fabricated a unique fluorescent probe for convenient ΔΨm visualization based on hot-band absorption and controllable anti-Stokes shift emission. The robust probe was excitable via hot-band absorption and emitted anti-Stokes upconversion emission and Stokes downconversion fluorescence simultaneously. The anti-Stokes emission could be efficiently inhibited upon the binding to RNA. The cationic probe targeted mitochondria in living cells with high ΔΨm and displayed both anti-Stokes green emission and ordinary red fluorescence. After the decrease of ΔΨm, the probe immigrated out of mitochondria to RNA and nucleolus, which showed only red emission owing to the inhibition of anti-Stokes fluorescence. In this manner, the ΔΨm could be visualized in dual-color mode. The probe enabled clearly monitoring the reversible changes in ΔΨm and was successfully employed to visualize oxidative damage of living cells. The decrease of ΔΨm in living tissues was also successfully observed with the newly designed probe.

Innovative ratiometric optical strategy: Nonconjugated polymer dots based fluorescence-scattering dual signal output for sensing mercury ions

A new ratiometric platform was developed for sensing Hg2+, which combined fluorescence and scattering simultaneously. This ratiometric strategy reflected superiorities over conventional methods, since the two independent signals at irrelevant categories meet the requirements of sufficient wavelength separation, stimulation under one excitation, and collection on single instrument. Herein, nonconjugated polymer dots (N-PDs) were served as the recognition unit for Hg2+ with turn-off fluorescence and turn-on scattering. Additionally, two signal collection tactics were proposed to achieve fluorescence and scattering in a window: one was to record down-conversion fluorescence and second-order scattering spectra (FL@SOS), and the other was to gather the fluorescence excited by second-order diffraction light and first-order scattering (SODL-FL@FOS). This ratiometric sensor exhibited outstanding performance toward Hg2+ in the range of 0.1–50 μM with the detection limit of 27 nM. By contrast, the present proposal provided a more ingenious and scalable way to construct ratiometric sensor than traditional approach.

Erbium-doped graphene quantum dots with up- and down-conversion luminescence for effective detection of ferric ions in water and human serum

Herein, the erbium-doped graphene quantum dots (Er-GQDs) with up- and down-conversion fluorescence have, for the first time, been hydrothermally fabricated at lactose-to-erbium pentahydrate ratio of 50, and then employed as the nanosensing probe to detect Fe3+ ions in aqueous and human serum samples. The surface characterization shows that the 1.8 at% Er is successful incorporated into 2–8 nm GQD lattice to form Er-GQD nanoparticles. The Er3+-doped GQDs exhibit both up and down-conversion luminescence properties after excitation with 730-nm visible light and 360-nm UV light, respectively. Both up- and down-conversion fluorescence properties of Er-GQDs show excellent analytical performance toward Fe3+ detection. A wide dynamic range of 4 orders of magnitude with limits of detection of 2.8–11.2 nM is observed when down-conversion property of Er-GQD is used for Fe3+ detection in PBS and human serum. Moreover, both up- and down-conversion fluorescence behaviors exhibit superior selectivity over 16 metal ion and 19 organic interferences. Results clearly indicate the feasibility of using Er-GQDs with both up- and down-conversion fluorescence properties as the nanosensing probe for highly selective and sensitive detection of metal ions in various environmental media, which can extend the application of up-conversion application from inorganic materials to carbon based nanomaterials for label-free detection of analysts in environmental and biological samples.

Facile, ultrafast synthesis of up- and down-conversion fluorescent carbon dots for highly sensitive detection of hematin

Fluorescent carbon dots (CDs) are promising zero-dimensional carbon nanomaterials with semiconductor-like properties, which have attracted tremendous attention owing to their fascinating features such as excellent optical performance, chemical inertness, and low toxicology. In this investigation, Mg-doped CDs (Mg-CDs) with up- and down-conversion fluorescence (FL) were prepared within 2 min through a one-pot, facile and ultrafast microwave method. The obtained Mg-CDs showed excitation-independent blue emission and were potentially applied for the detection of hematin based on the strong inner filter effect (IFE). The FL intensity ratio (I0/I) of the synthesized Mg-CDs were proportional to the concentration of hematin in the range of 0.1–75 μM with the limit of detection of 25 nM for Mg-CDs-0.1 and 0.01–25 μM with the limit of detection of 1 nM for Mg-CDs-0.5. Overall, this selective and sensitive assay using Mg-CDs obtained through the current microwave method was believed to demonstrate significant application prospects in complex matrices owing to its simplicity and specificity for hematin.

2D Janus membrane and derivative 3D dual-wall Janus shaped tube affording dual aeolotropic conduction, up/down conversion luminescence and superparamagnetism

New-typed two-dimensional (2D) bilayer Janus nanobelts array membrane (marked as BJNAM) is devised and constructed via sequential parallel electrospinning utilizing one-dimensional (1D) Janus nanobelt as conductive and building unit. BJNAM comprises up-to-down two-layer membranes closely connected to form Janus membrane. Owing to its exceptive structure, the BJNAM achieves multi-functionalities of dual aeolotropic conduction, dual-colored up-conversion and down-conversion fluorescence and superparamagnetism. The specific structure of BJNAM realizes macroscopic partition, Janus nanobelt used as building unit actualizes micro-partition, and high integration of micro-partition with macro-partition is synchronously realized in the novel 2D BJNAM, and partition structures assist to reduce adverse mutual influences among diverse functional materials by isolating and limiting them on their own areas on the macro and micro level to achieve excellent poly-functionalities. Furthermore, four kinds of three-dimensional (3D) dual-wall Janus shaped tubes are easily obtained by curling the 2D BJNAM through different plans and the 3D dual-wall Janus shaped tubes possess the same properties as the 2D BJNAM, implying that the structural evolution from microscopic 1D Janus nanobelt to macroscopic 2D dual aeolotropic conductive membrane then to macroscopic 3D Janus shaped tube is achieved. The newly-manufactured 2D and 3D materials have potentials in oil-water separation, biomedicine and flexible electronics.

Facile Synthesis of Fluorescence/Temperature Multisensitive Hybrid Hydrogels

Hybrid hydrogels based on poly(N-isopropylacrylamide) and poly(acrylamide) containing CdTe quantum dots with UV sensitive response and including NaYF4:Yb/Er nanoparticles have been prepared through glow discharge electrolysis plasma. The fluorescence characteristic and temperature sensitivity of the prepared hydrogels have been most extensively studied. In addition, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry were determined to characterize the morphology, degree of crystallinity and the phase transformations of the hydrogels. The results suggested that the phase transition temperature of the hydrogels was 32.5°C and the hydrogels had good up-conversion and down-conversion fluorescence properties. Moreover, hybrid hydrogels had a reversible temperature response performance.

Design of Up-Conversion Fluorescence Imaging Device Based on Inverted Fluorescence Microscope

Fluorescence imaging is a widely used technique for microscopic observation in basic biomedical research. Currently, most of the commercial fluorescence microscopes are based on the design of down-conversion fluorescence reagent. In this paper, an up-conversion fluorescence imaging device based on inverted fluorescence microscope is designed. The device uses 980nm near-infrared as the excitation source and the inverted fluorescence microscope as the platform to transform its internal optical system and apply it to up-conversion fluorescence imaging. Through a large number of experimental studies, the stability and linearity of the equipment were verified, and the relationship between incubation time and intake of Hela cells was explored. The experimental results showed that when the laser power was 1. 5W and UCNPs@ DSPE-PE concentration was 0. 05mg/ml, the uptake of Hela cells reached the saturation state.

Studies on the influence of structure units on the state of ytterbium ions in TeO2-based glasses

Abstract

Thermometric analysis of the near-infrared emission of Nd3+ in Y2SiO5 ceramic powder prepared by combustion synthesis

Nd3+:Y2SiO5 crystalline ceramic powder prepared by combustion synthesis exhibited down-conversion fluorescence when the sample was exposed to CW laser radiation at 532 nm. Three emission bands centered at 879.36 nm, 804.86 nm and 753.21 nm, corresponding to transitions (4F7/2,4S3/2) → 4I9/2, (4F5/2,2H9/2) → 4I9/2 and 4F3/2 → 4I9/2, were observed. A noticeable change on the relative intensities of the transitions in the temperature range 298–673 K occured due to thermal coupling among the excited electronic states. By means of the fluorescence intensity ratio (FIR) technique, we obtained a maximum absolute sensitivity of 2.5 × 10−3 K−1 at 650 K and a relative sensitivity of 2.11% K−1 at 300 K for this material. The Judd-Ofelt standard intensity parameters ratio Ω4/Ω6, a spectroscopy quality factor for laser applications, was estimated from the FIR thermometry data and a value of 1.75 was obtained. The potential use of this material in thermal sensing at the first biological window (700–950 nm) and in lasing applications is discussed.

Tri-doped alkaline earth sulfide nanoparticles as a new class of highly efficient probe with near-IR stimulated fluorescence for in vivo and ultrasensitive bacteria targeted imaging

Near-infrared light (NIR) stimulated anti-Stokes fluorescence imaging has unique advantages compared with conventional down-conversion fluorescence imaging, especially applied in bioimaging. However, the existing NIR induced fluorescence nanomaterials like up-conversion nanoparticles are restricted by issues like insufficient fluorescent brightness. Hence we introduce triple-doped red emission (CaS:Eu,Sm,Mn), and blue emission (SrS:Ce,Sm,Mn) alkaline earth sulfide nanoparticles (AES NPs) with ultra-bright NIR stimulated fluorescence, high brightness and variable emission wavelength make them very promising as a novel type of biolabeling probe. In this work, CaS:Eu,Sm,Mn nanoparticles and SrS:Ce,Sm,Mn nanoparticles are covalently linked with bacteria targeting moiety (teicoplanin or polymyxin B) for in-vivo and in-situ imaging of Gram-positive/negative bacteria, the in-vivo experiment demonstrates the functionalized AES NPs are able to adequately distinguish and differentiate bacterial infection between aseptic inflammation. Significantly, non-overlapping emission bands of this two AES NPs make Gram-positive/negative strain selective fluorescence imaging possible, and intense fluorescence under 980 nm light irradiation enables both high sensitivity and deep tissue imaging. Further, low biological toxicity of the bacteria targeting probe based the AES NPs is assessed. We conclude that CaS/SrS based system has a high potential and practical value for in vivo bacteria fluorescent imaging and detection.