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In this paper, we have designed long afterglow luminescent MgGeO 3 :Mn 2+ ,Yb 3+ ,Li + (MGO) nanoparticles in the first (NIR-I) and second (NIR-II) biological windows. Yb 3+ ions served not only as the trap center to enhance the NIR-I long afterglow emission of Mn 2+ at 680 nm, but also as an emitting center to produce a NIR-II long afterglow emission at ∼1000 nm. Furthermore, we have found the addition of Li + can greatly increase the NIR-II afterglow emission of Yb 3+ and the optimal amount of Mn 2+ , Yb 3+ and Li + was found to be 0.1, 0.5 and 0.5 mol%, respectively. The MGO nanoparticles synthesized using sol-gel methods showed a uniform morphology with a diameter of 50-100 nm, which were suitable for applications in bioimaging. More importantly, we have found MGO nanoparticles can be effectively excited to produce long persistent NIR-I and II luminescence using soft X-rays, suggesting that low dosage soft X-rays can also serve as a more powerful and deep tissue excitation source to recharge MGO nanoparticles. Furthermore, the MGO nanoparticles can also be re-excited to produce photo-stimulated emission under the irradiation of 650 and 808 nm NIR lasers. The in vivo imaging results have shown that MGO nanoparticles modified with folic acid (FA) can effectively realize super long-term targeted in vivo imaging of inflammation with a high sensitivity via recharging using soft X-rays and NIR lasers, which can provide not only an accurate diagnosis of inflammation, but also long-term monitoring of possible changes in the focus of inflammation in real time.

Persistent luminescence nanoparticles (PLNPs) with rechargeable near-infrared afterglow properties attract much attention for tumor diagnosis in living animals since they can avoid tissue autofluorescence and greatly improve the signal-to-background ratio. Using UV, visible light, or X-ray as excitation sources to power up persistent luminescence (PL) faces the challenges such as limited tissue penetration, inefficient charging capability, or tissue damage caused by irradiation. Here, it is proved that radiopharmaceuticals can efficiently excite ZnGa 2 O 4 :Cr 3+ nanoparticles (ZGCs) for both fluorescence and afterglow luminescence via Cerenkov resonance energy transfer as well as ionizing radiation. 18 F-FDG, a clinically approved tumor-imaging radiopharmaceutical with a short decay half-life around 110 min, is successfully used as the internal light source to in vivo excite intravenously injected ZGCs for tumor luminescence imaging over 3 h. The luminescence with similar decay time can be re-obtained for multiple times upon injection of 18 F-FDG at any time needed with no health concern. It is believed this strategy can not only provide tumor luminescence imaging with high sensitivity, high contrast, and long decay time at desired time, but also guarantee the patients much less radiation exposure, greatly benefiting image-guided surgery in the future., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The development of nanotechnology has drawn increased attention to the risks of nanoparticles (NPs). In this work, the near-infrared persistent luminescence imaging technique was used to track the biodistribution of NPs in vivo in zebrafish. Zebrafish were used as a vertebrate animal model to show NPs distribution and the effects of exposure. ZnGa 2 O 4 :Cr (ZGOC) was chosen as the probe in this work. In continuous exposure experiments, the results showed more particles accumulated in the intestines than in the gills in both groups. In both the gills and abdomen, the NPs contents were greater in the ZGOC-NH 2 -treated groups than in the ZGOC groups, and the NPs caused damage to the gills and intestines. Removal exposure experiments indicated that ZGOC and ZGOC-NH 2 could be excreted from the body. The metabolism, excretion of NPs, the quantification and monitoring of NPs behavior in biological systems should be examined in further studies.

Multifunctional theranostic nanoplatforms greatly improve the accuracy and effectiveness in tumor treatments. Much effort has been made in developing advanced optical imaging-based tumor theranostic nanoplatforms. However, autofluorescence and irradiation damage of the conventional fluorescence imaging technologies as well as unsatisfied curative effects of the nanoplatforms remain great challenges against their wide applications. Herein, we constructed a novel core-shell multifunctional nanoplatform, that is, chromium-doped zinc gallogermanate (ZGGO) near-infrared (NIR) persistent luminescent nanoparticles (PLNPs) as a core and zeolitic imidazolate framework-8 (ZIF-8) as a shell (namely ZGGO@ZIF-8). The ZGGO@ZIF-8 nanoplatform possessed dual functionalities of the autofluorescence-free NIR PersL imaging as well as the pH-responsive drug delivery, thus it has high potential in tumor theranostics. Notably, the loading content of doxorubicin (DOX) in ZGGO@ZIF-8 (LC = 93.2%) was quite high, and the drug release of DOX-loaded ZGGO@ZIF-8 was accelerated in an acidic microenvironment such as tumor cells. The ZGGO@ZIF-8 opens up a new material system in the combination of PLNPs with metal-organic frameworks and may offer new opportunities for the development of advanced multifunctional nanoplatforms for tumor theranostics, chemical sensing, and optical information storage.

The aggregation of nanoparticles (NPs) on the cell membrane is crucial for the cellular uptake process and has important biological implications in protein-membrane interactions. In this paper, we systematically investigate how the aggregation is regulated by the mechanical properties of the NP-membrane system, including the membrane tension, and the size and shape of the NPs. Results show that when NPs aggregate parallel to the cell membrane, increasing the membrane tension will modulate the membrane-mediated interaction between the NPs from attractive to attractive-repulsive and finally to purely repulsive. In contrast, the membrane-mediated interaction is attractive and independent of the membrane tension when the NPs aggregate to a tubular configuration. For the aggregation of NPs of different sizes, the large-size NP is wrapped to a greater extent than the small-size NP. For the aggregation of nonspherical NPs, low aspect ratio and weak NP-membrane adhesion strength lead to the side-to-side configuration, whereas a system with a high aspect ratio and strong NP-membrane adhesion strength prefers the tip-to-tip configuration. Importantly, NPs of different sizes and anisotropic shapes are found to facilitate the aggregation process by reducing the energy barrier that should be overcome during the aggregation. The results reveal the mechanism of the aggregation of NPs on the cell membrane and provide guidelines to the design of NP-based drug delivery systems.

Near-infrared (NIR) persistent luminescence nanoparticles (NPLNPs) have become one of the most promising candidates for bioimaging. Different from the other fluorescence nanoprobes, the NIR persistent luminescence of NPLNPs can last for a long time after excitation, double exposure that is nanoparticles and light exist during the long-term bioimaging. However, to date, the potential risk of nanoparticles and NIR persistent luminescence of NPLNPs is still unknown. In this study, Cr3 + -doped zinc gallate, Zn 1.1 Ga 1.8 Sn 0.1 O 4 :Cr 3+ (ZGO), the most promising NPLNPs in bioimaging, was chosen as a representative for potential risk assessment. We evaluated the potential risk of nanoparticles and NIR persistent luminescence of ZGO for a long period of time. In vitro study showed that the ZGO possessed a low cytotoxicity. In vivo biodistribution results showed that the ZGO mainly accumulated in the reticuloendothelial system after intravenous injection and could be gradually cleared from the body by digestive system. In addition, the ZGO did not exhibit appreciable toxicity in mice over a period of 60 days. It's also worth mentioning that long-term NIR persistent luminescence of ZGO did not exhibit obvious toxicities both in vitro and in vivo. Our results provide important information with regards to the risk of NPLNPs in long-term bioimaging.

Persistent luminous nanoparticles (PLNPs) have been capturing increasing attention in biomedical imaging because of their long-life emission and concomitant benefits ( e.g., zero-autofluorescence background, high signal-to-noise ratio). Although there are quite some synthetic methodologies to synthesize PLNPs, those for constructing functional structured PLNPs remain largely unexplored. Herein we report the design principle, synthesis route, and proof-of-concept applications of hollow structured PLNPs with near-infrared (NIR) persistent luminescence, namely afterglow, and tunable sizes for tumor afterglow imaging and chemical/photodynamic therapies. The design principle leverages on the crystallization of the immobilized parent ions on the purgeable carbon spheres. This strategy provides large and size-tunable hollow cavities to PLNPs after calcination. Building on the hollow cavity of PLNPs, high chemical drug (DOX) or photosensitizer (Si-Pc) loading can be achieved. The DOX/Si-Pc-loaded hollow PLNPs exhibit efficient tumor suppression based on the features of large cavity and afterglow of PLNPs. These hollow structured PLNPs, like traditional solid PLNPs, are quite stable and can be repeatedly activated, and particularly can selectively target tumor lesion, permitting rechargeable afterglow imaging in living mice. Our research supplies a strategy to synthesize hollow structured PLNPs, and hopefully it could inspire other innovative structures for cancer theranostics.

A complete understanding of the interactions between nanoparticles (NPs) and the cell membrane is essential for the potential biomedical applications of NPs. The rotation of the NP during the cellular wrapping process is of great biological significance and has been widely observed in experiments and simulations. However, the underlying mechanisms of the rotation and their potential influences on the wrapping behavior are far from being fully understood. Here, by coupling the rotation of the NP with the diffusion of the receptors, we set up a model to theoretically investigate the wrapping pathway and the internalization rate of the rotatable NP in the receptor-mediated endocytosis. Based on this model, it is found that the endocytosis proceeds through the symmetric-asymmetric or asymmetric-symmetric-asymmetric wrapping pathway due to the bending and membrane tension competition induced rotation of NP. In addition, we show that the wrapping rate in the direction that the wrapping proceeds can be largely accelerated by the rotation. Moreover, the time to fully wrap the NP depends not only on the size and shape of the NP but also on its rotation and initial orientation. These results reveal the roles of the shape, rotation, and initial orientation of the NP on the receptor-mediated endocytosis and may provide guidelines for the design of NP-based drug delivery systems.

Multifunctional nanoplatforms with multimodal imaging and cancer therapy capabilities have attracted attention in biomedical applications. Near-infrared persistent luminescence nanoparticles (NPLNPs) were considered one of the most promising candidates for constructing multifunctional nanoplatforms due to the absence of in situ excitation and high signal-to-noise ratios (SNRs). Here, we report a novel NPLNP mSiO 2 @Gd 3 Ga 5 O 12 :Cr 3+ , Nd 3+ (mSiO 2 @GGO) as multifunctional nanoplatforms for multimodal imaging and cancer therapy. These NPs exhibited a persistent luminescence (745 nm) of more than 3 h in the first near-infrared window (NIR-I) after UV excitation, which can realize high SNRs and long-term in vivo imaging. Moreover, these NPs showed excellent NIR luminescence (1067 nm) in the second near-infrared window (NIR-II) under 808 nm excitation, which is more suitable for deep tissue imaging due to the lower photon scattering and deeper tissue penetration of NIR-II luminescence. Furthermore, the host Gd 3 Ga 5 O 12 with high Gd 3+ concentration showed a high r 1 value (10.70 mM -1  s -1 ) and was suitable for T 1 MR imaging. The mesoporous silica nanoparticles (mSiO 2 ) served as a framework to control the mSiO 2 @GGO particle morphology and provide low toxicity and drug loading capacity for cancer therapy., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Vitamin E (VE) exerts promising antioxidant activities against free radicals. However, its therapeutic efficacy and practical application are greatly restricted as a result of poor solubility, instability and low bioavailability. In this work, novel amino functionalized mesoporous silica nanoparticles (MSNs) were employed as the smart carriers to encapsulate Vitamin E acetate by the combination of soft-template method and recrystallization approach. Typically, two different surfactants were used as organic templates to fabricate different MSNs with various pore size distributions (∼4nm and ∼25nm). According to the characterization results such as Brunauer-Emmet-Teller (BET), fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), thermal gravity analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD), dynamic light scattering (DLS) and UV-vis diffuse reflectance spectroscopy, the drug delivery systems were successfully fabricated and the loading capacity (LC%) and entrapment efficiency (EE%) were also assessed. In addition, the results revealed that the VE loaded nanoparticles dispersed very well in PBS (pH = 7.4) and released VE in a pH-responsive manner. Importantly, the antioxidant effects of the VE loaded nanoparticles were also investigated by DPPH assays after exposure to air for 48h, showing that VE molecules encapsulated inside the mesoporous channels suffered from less degradation, compared to the pure VE. In vitro cell tests and hemolytic experiments revealed the outstanding biocompatibility and low cytotoxicity. In conclusion, the functionalized mesoporous silica combined with VE might act as potential antioxidant drug formations in clinical application., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Near infrared (NIR)-emitting persistent luminescent nanoparticles (NPLNPs) have attracted much attention in bioimaging because they can provide long-term in vivo imaging with a high signal-to-noise ratio (SNR). However, conventional NPLNPs with large particle sizes that lack modifiable surface groups suffer from many serious limitations in bioimaging. Herein, we report a one-step synthesis of amino-functionalized ZnGa2O4:Cr,Eu nanoparticles (ZGO) that have an ultrasmall size, where ethylenediamine served as the reactant to fabricate the ZGO as well as the surfactant ligand to control the nanocrystal size and form surface amino groups. The ZGO exhibited a narrow particle size distribution, a bright NIR emission and a long afterglow luminescence. In addition, due to the excellent conjugation ability of the surface amino groups, the ZGO can be easily conjugated with many bio-functional molecules, which has been successfully utilized to realize in vitro and in vivo imaging. More importantly, the ZGO achieved re-excitation imaging using 650 nm and 808 nm NIR light in situ, which is advantageous for long-term and higher SNR bioimaging.

A fundamental understanding of the interactions between nanoparticles (NPs) and the cell membrane is essential to improve the performance of the NP-based biomedical applications and assess the potential toxicity of NPs. Despite the great progress in understanding the interaction between individual NP and the membrane, little is known about the interaction between multiple NPs and the membrane. In this work, we investigate the wrapping of two parallel elongated NPs by the membrane, taking the NP-NP electrostatic interaction and van der Waals (vdW) interaction into consideration. Three types of NPs, namely the rigid NPs with circular and elliptic cross-sections and the deformable NPs, are systematically investigated. The results show that the electrostatic interaction would enhance the tendency of the independent wrapping and inhibit the rotation of the elongated and equally charged NPs with elliptic cross-sections. Under the vdW interaction, the competition of the NP-NP adhesion and the membrane elastic energies with the NP-membrane adhesion energy leads the NPs to be wrapped cooperatively or independently. For the system with elongated NPs with elliptic cross-sections, the NPs are more likely to be wrapped independently as the shapes become more anisotropic and the NPs would rotate to contact each other with the flat sides in the cooperative wrapping configuration. Moreover, the soft NPs are more likely to be wrapped cooperatively compared with the stiff NPs. These results may provide guidelines to control the internalization pathway of NPs and improve the efficiency of NP-based drug delivery systems.

Due to their bactericidal and photocatalytic characteristics, silver nanoparticles (Ag NPs) and titanium dioxide nanoparticles (TiO2 NPs) are widely used in the fields of environment and physiology. Once these untreated nanoparticles are released into an aquatic environment and encounter one another, there is more uncertainty about their fate and ecotoxicological risks compared with the single nanoparticles. To expand our knowledge of the health and environmental impacts of nanoparticles, we investigated the possible risk of the co-existence of TiO2 NPs and Ag NPs in an aquatic environment using ciliated protozoa (Tetrahymena pyriformis) as an aquatic animal model. In this study, silver ion (Ag(+)) release and physicochemical properties, as well as their effect on oxidative stress biomarkers, were monitored. Continuous illumination (12,000 lx) led to the 20.0% decrease in Ag(+) release in comparison with dark conditions, while TiO2 NPs and continuous illumination resulted in decreasing the Ag(+) concentration to 64.3% in contrast with Ag NPs-only suspensions. Toxicity tests indicated that different illumination modes exerted distinct effects of TiO2 NPs on the toxicity of Ag NPs: no effects, antagonism and synergism in dark, natural light and continuous light, respectively. In the presence of 1.5mg/L (18.8 μM) TiO2 NPs, the toxicity of 1.5 mg/L (13.9 μM) Ag NPs was reduced by 28.7% and increased by 6.93% in natural light and 12,000 lx of continuous light, respectively. After culturing in 12,000 lx continuous light for 24h, SOD activity of the light control surged to 1.96 times compared to the dark control (P<0.001). TiO2 NPs induced a reduction of CAT activity by an average of (36.1±1.7) % in the light. In the natural light reductions in the toxicity of Ag, NPs decrease Ag(+) concentrations via adsorption of Ag(+) onto TiO2 NPs surfaces. The enhancement of Ag NPs toxicity can contribute to the formation of activated TiO2-Ag NPs complexes in continuous light. The existence of TiO2 NPs in various illumination modes changed the surface chemistry of Ag NPs and then led to different toxicity effects. TiO2 NPs reduce the environmental risks of Ag NPs in natural light, but in continuous light, TiO2 NPs enhance the environmental risks of Ag NPs., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A simple and effective solvent swelling method was developed for the preparation of poly(methyl methacrylate) (PMMA)/europium (Eu) complex hybrid nanospheres. Transmission electron microscopy and dynamic light scattering results indicate that the as-prepared PMMA-Eu nanoparticles had a spherical morphology, with a narrow particle size distribution ranging from 100-200 nm. The PMMA-Eu nanospheres exhibited strong red emissions with a maximum peak at 612 nm under UV excitation, and the luminescence lifetime of the Eu complex was enhanced after it was swollen into PMMA nanospheres. Furthermore, the luminescence intensity of the PMMA-Eu nanospheres was very stable in various severe media, including aqueous solutions with various pHs, 1 m M Ca2+, 1 m M Fe2+, 1 m M Cu2+, 0.1 M phosphate-buffered saline solution, 1 m M citric acid solution, 1 m M lysine, and 1 m M glutamic acid. After the nanospheres were incubated at various temperatures for 1 h, the luminescence properties remained stable when the temperature was less than 40°C yet decreased slightly between 40 and 60°C and decreased rapidly at higher temperatures. These luminescent nanospheres were successfully applied in the luminescence-sensing assay of hydrogen peroxide and exhibited a high sensitivity and broad linear concentration range. Because of their unique luminescence properties, the as-synthesized PMMA-Eu nanospheres are expected to have great potential for use as luminescent labels or probes for long-time imaging and analysis in which severe media situations are present. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Abstract: The principle of color conversion process was used to generate red long-lasting phosphorescence (LLP) using SrAl2O4:Eu, Dy (SAO) as primary light source and rhodamine B encapsulated mesoporous silica nanoparticles (MCM-R) as effective color conversion agent. The phosphorescence spectra of MCM-R/SAO hybrid samples show green peaks from 425nm to 550nm and red peaks from 550nm to 700nm, which can be attributed to the phosphorescence of SAO and the fluorescence of MCM-R, respectively. The phosphorescence color can be adjusted from green to red by changing the mass ratio of MCM-R/SAO. When the mass ratio of MCM-R/SAO increases from 0.05 to 1.5, a blue shift for the green peak and a red shift for the red peak of the phosphorescence spectra can be observed and the intensity of the red emission peak increase relatively towards the green one. The phosphorescence decay curves show that MCM-R and SAO have similar decay dynamics and the MCM-R can inherit the LLP properties of SAO. The phosphorescence decay spectra indicate that the MCM-R/SAO hybrid can retain constant and steady visual phosphorescence color. The red phosphorescence can be seen in the dark with naked eyes for more than 5h. So, the red LLP can be successfully achieved based on the principle of color conversion process. [Copyright &y& Elsevier]

A novel kind of photosensitive water-dispersible polyaniline (PANI) nanoparticles was designed and prepared by template synthesis using a photo-responsive vinyl-coumarin (VM)/2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) copolymer micelle containing coumarin moieties. The resulting PANI nanoparticles exhibited reversible photo-crosslinking and photo-decrosslinking behavior similar to coumarin moiety upon irradiation with different UV light as verified by UV-vis absorption. In addition, photoinduced size change of the PANI nanoparticles after 365 nm UV light irradiation was successfully monitored by dynamic light scattering and transmission electron microscopy measurements, further confirming the photosensitivity of the obtained PANI nanoparticles by the incorporation of VM/AMPS copolymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

Abstract: From the viewpoint of utilizing a mechanoluminescent (ML) material as a light source, the surface of the ML material should have the most effective photoreaction with the strongest photointensity from the ML material. A hybrid material that combines an ML material and a photoreactant material is a promising way of accomplishing this. This paper discusses a preparation method for a hybrid material consisting of the ML material and TiO2 photocatalytic nanoparticles. By using the surface sol–gel method, we succeeded in immobilizing the TiO2 photocatalytic nanoparticles on the surface of the ML material, thus preparing a hybrid material where the nanoparticles took over the original mechanoluminescence and photocatalysis activities. [Copyright &y& Elsevier]

Abstract: In this paper nanosized luminescent materials YVO4:Sm and YVO4:Dy were synthesized by complex-based sol–gel method. A certain amount of soluble starch participates in this synthesis as a chelate agent. Homogeneous and fine powders have been successfully prepared because soluble starch consists of long-chain glucose units which cannot only provide chelating units but also hinder the growth of nanoparticles. The experimental results have proved that the host YVO4 can effectively transfer the absorbed energy to the activators Sm3+ and Dy3+. Under the excitation of the host absorption, phosphors can emit yellow light for YVO4:Dy3+ nanoparticles and orange light for YVO4:Sm3+ nanoparticles, respectively. [Copyright &y& Elsevier]

Abstract: In this paper, thulium doped ZrO2 nanocrystals with different phases were prepared by Pechini sol–gel complex method. The effects of host structure, phases and concentration on luminescence properties of Tm3+ ions were investigated. With the increase of the concentration of Tm3+ ions, the phosphors phase transformed from monoclinic to tetragonal structure and all the phosphors emitted blue light. However, because the environment symmetry around Tm3+ in m-ZrO2 (C2h) is worse than that of t-ZrO2 (D4h), there were still obvious differences in the emission and excitation. The reason was investigated with the help of energy level diagram. In addition, the quenching concentration of Tm3+ in ZrO2 host is 1 m/m%. [Copyright &y& Elsevier]

Abstract Inflammation is implicated in many human diseases, thus the diagnosis of inflammation is very important for the early treatment of diseases associated with inflammation. However, the high-sensitivity diagnosis of inflammation remains difficult. Near-infrared (NIR) persistent luminescence nanoparticles (PLNPs) were considered one of the most promising candidates for high-sensitivity bioimaging due to being free of autofluorescence. In this study, we synthesized PLNPs Zn 1.1 Ga 1.8 Ge 0.1 O 4 :Cr3+ (ZGG) which demonstrated low cytotoxicity, excellent NIR persistent luminescence. We conducted the visualization of inflammation using these nanoparticles. The results indicated that the surface states of the ZGG influenced the progression of macrophage phagocytosis in vitro. ZGG-NH 2 demonstrated higher levels of internalization compared with ZGG-OH and ZGG-PEG. However, in contrast to the in vitro results, ZGG-PEG exhibited a greater ability to facilitate the visualization of inflammation in vivo. The long chains of PEG on the ZGG-PEG surfaces resulted in a lower reticuloendothelial system capture rate compared with both ZGG-OH and ZGG-NH 2. A higher concentration of the ZGG-PEG would cycle through the inflammation site, thereby inducing a high level of ZGG-PEG retention and thus yielding the strongest luminescent signal. Taken together, the results of this study demonstrate a simple and novel method for high-sensitivity visualization of inflammation in vivo. Highlights • Near-infrared persistent luminescence nanoparticles were successfully synthesized. • These nanoparticles showed low cytotoxicity and excellent NIR persistent luminescence. • We can realize macrophage imaging and inflammation imaging using these nanoparticles. [ABSTRACT FROM AUTHOR]

Here, a kind of porous nanoparticles GdAlO 3 :Cr 3+ , Sm 3+ (GAO:Cr,Sm) which own magnetic resonance and long persistent luminescent properties have been synthesized. The spherical morphology and narrow size distribution would allow the GAO:Cr,Sm nanoparticles to be utilised as a drug carrier and the drug release results indicate that the GAO:Cr,Sm drug carriers have an excellent drug sustained properties. Applying the Cr 3+ and Sm 3+ coped with gadolinium aluminate as the NIR persistent luminescence center and the energy transfer resonance from Gd 3+ to Cr 3+ , these nanoparticles exhibit excellent NIR persistent luminescence at 732 nm under the UV irradiation of 254 nm and it can persist for about half an hour. In addition, they possess a longitudinal relaxivity (r 1 ) value of 4.75 mM −1 s −1 , which means that these nanoparticles could be applied for MR imaging as contrast agents. Carboxymethyl Chitosan was modified on the surface of GAO:Cr,Sm nanoparticles to make them owning excellent biocompatibility and low toxicity and these nanoparticles were successful to realize in vivo imaging. Hence, the well-defined nanoprobes of GAO:Cr,Sm exhibit great potential in biomedicine as trackable drug carriers and in vivo imaging agent due to the dual-model imaging property. [ABSTRACT FROM AUTHOR]