Core-shell Upconversion Nanoparticles Research Articles

“Integrated diagnosis and treatment” of upconversion nanocomposite hydrogel for osteoarthritis treatment

Osteoarthritis (OA) is a common degenerative joint disease for which there is no definitive treatment. Mesenchymal stem cells (MSCs) can be differentiated into many types of cells such as chondrocytes, which have been used for OA treatment. How to keep the cell viability and promote the chondrogenic differentiation after MSCs transplantation into the knee joint cavityiscrucial. In this study, upconversion nanocomposite hydrogel was developed for integrated diagnosis and treatment of OA. The Er doped core–shell upconversion nanoparticles (UCNPs) were synthesized first and coated on mesoporous silica (UCNP@mSiO2). Then, an H2O2-sensitive thioketal (TK) linker (MAL-PEG-TK-NHS) was attached to the UCNP@mSiO2 surface to link capsular β-cyclodextrin (NH2-β-CD) and black hole quencher (NH2-BHQ3) to form functionalized UCNPs. After loading the drug kartogenin (KGN) that can induce chondrogenic differentiation of MSCs, the UCNP/KGN nanocomposites were mixed with VitroGel to formed the upconversion nanocomposite hydrogel (UCNP/VitroGel). The UCNP/VitroGel could allow MSCs to be implanted well and maintain good survival in vitro. In the presence of hydrogen peroxide (H2O2), the TK bond breakage and triggered release BHQ to recover the fluorescence of UCNPs for ROS detection, and the β-CD also left from the surface of UCNPs to release KGN for inducing the chondrogenic differentiation of MSCs. Thus, the UCNP/VitroGel could detect the ROS after inject into the knee joint cavity for OA diagnosis first via the fluorescence recovery of UCNPs under the 980 nm near-infrared light. And then the KGN release from UCNP/KGN nanocomposites in the environment of OA to induce the chondrogenic differentiation of MSCs for the treatment of OA. This UCNP/VitroGel will be a powerful tool for “integrated diagnosis and treatment” of OA.

A novel core-shell up-conversion nanoparticles immunochromatographic assay for the detection of deoxynivalenol in cereals

Deoxynivalenol (DON) toxin is a type B group of trichothecene mycotoxins mainly originating from specific Fusarium fungi, seriously harming human and livestock health. Herein, a novel core-shell up-conversion nanoparticles immunochromatographic assay (CS-UCNPs-ICA) was developed for deoxynivalenol based on the competitive reaction principle. By exploiting the fluorescence intensity of the T and C lines of CS-UCNPs-ICA, the concentrations of DON were obtained sensitively and precisely under optimized conditions in 5 min with a detection limit of 0.1 ng/mL. The CS-UCNPs-ICA strips only specifically detect DON and its derivatives (3-Ac-DON and 15-Ac-DON), with no cross-reaction with other mycotoxins. The low CV values illustrated a modest intra- and inter-assay variation, confirming the superior precision of this method. In the spiked experiment, the mean recoveries of corn and wheat ranged from 94.74% to 100.90% and 96.21%–104.81%, respectively. Furthermore, the approach generated results that were in good agreement with data from HPLC and ELISA analyses of naturally contaminated feed and cereals, confirming that the significant advantages of proposed strips were their high practicality, rapidness, and simplicity. Therefore, the CS-UCNPs-ICA strips platform serves as a promising candidate for developing new approaches for rapid testing or high throughput screening from DON in food products.

A magnetic-enhanced FRET biosensor for simultaneous detection of multiple antibodies

Accurate, rapid and sensitive detection of specific immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies in human samples is crucial for preventing and assessing pandemics, especially in the case of recent COVID-19 outbreaks. However, simultaneous and efficient detection of IgG and IgM in a single system remains challenging. Herein, we developed a multicolor nanosystem capable of quantitatively analyzing anti-SARS-CoV-2 IgG and IgM with high sensitivity within 20 ​min. The detection system consists of core-shell upconversion nanoparticles (csUCNPs), secondary antibodies labeled with fluorescent dyes (sab), and magnetic nanocrystals (PMF). By leveraging the Förster resonance energy transfer (FRET) effect, the photoluminescence (PL) intensity of blue and green regions is restored for IgG and IgM detection, respectively. Inspiringly, owing to the introducing of PMF, the limits of detection (LODs) of IgG and IgM tested are improved to 89 ​fmol ​L−1 and 19.4 ​fmol ​L−1, representing about 416-folds and 487-folds improvement over only-dye dependent system, respectively. Mechanistic investigations reveal that the high collective effect and surface energy transfer efficiency from csUCNPs to PMF contribute to the enhanced detection sensitivity. The assay enables us to quantify clinical vaccinated samples with high specificity and precision, suggesting our multicolor platform can be a promising alternative for clinical point-of-care serological assay.

Enhanced detection of acrylamide using a versatile solid-state upconversion sensor through spectral and visual analysis

Acrylamide (AM) generally forms in high-temperature processes and has been classified as a potential carcinogen. In this study, we put forward a maneuverable solid-state luminescence sensor using polydimethylsiloxane (PDMS) as the matrix coupled with upconversion nanoparticles as the indicator. The core-shell upconversion nanoparticles emitting cyan light were uniformly encapsulated in PDMS. Then it was further modified with complementary DNA of AM aptamer. The nanocrystalline fluorescein isothiocyanate isomer (FITC), coupled with AM aptamer, was attached to the surface of PDMS. FITC effectively quenched the upconversion luminescence through fluorescence resonance energy transfer (FRET). The introduction of AM resulted in preferentially bound to aptamer caused the separation of the quencher and the donor, and led to luminescence recovery. The developed sensor was applied for both spectral and visual monitoring, demonstrating a detection limit (LOD) of 1.00 nM and 1.07 nM, respectively. Importantly, in the actual foodstuffs detection, there is no obvious difference between the results of this study and the standard method, which indicates the developed method has good accuracy. Therefore, this solid-state sensor has the potential for on-site detection using a smartphone device and an Android application.

A Biomimetic Upconversion Nanobait-Based Near Infrared Light Guided Photodynamic Therapy Alleviates Alzheimer's Disease by Inhibiting β-Amyloid Aggregation.

Aberrant β-amyloid (Aβ) fibrillation is the key event in Alzheimer's disease (AD), the inhibition and degradation of which are recognized as a promising therapeutic strategy to alleviate the nerve damage of AD. Photodynamic therapy (PDT) holds great potential for modulation of Aβ self-assembly, which is nevertheless limited by the inefficient utilization of reactive oxygen species (ROS). Herein, an erythrocyte membrane (EM)-modified core-shell upconversion nanoparticle (UCNP/Cur@EM) is designed and fabricated as a biomimetic nanobait to improve the PDT efficiency in AD. The UCNP with the outlayer of mesoporous silica is synthesized to load a high amount of the photosensitizer (curcumin), the unique optical feature of which can trigger curcumin to generate ROS upon near-infrared light (NIR) irradiation. Integration of EM enables the biomimetic nanobait to attract Aβ peptides trapped in the phospholipid bilayer, restraining the growth of Aβ monomers to form aggregates and improving the utilization rate of ROS to degrade the preformed Aβ aggregates. In vivo studies demonstrate that UCNP/Cur@EM irradiated by NIR enables to decrease Aβ deposits, ameliorates memory deficits, and rescues cognitive functions in the APP/PS1 transgenic mouse model. A biocompatible and controllable way is provided here to inhibit the amyloid protein-associated pathological process of AD.

Attomolar-level detection of respiratory virus long-chain oligonucleotides based on FRET biosensor with upconversion nanoparticles and Au–Au dimer

Upconversion nanoparticles (UCNPs) are promising nanoprobes in DNA/RNA detection, such as respiratory viral RNAs, and siRNA in cancer. However, recent studies have indicated that the sensitivity of UCNP-based biosensors is restricted, ranging from picomolar to femtomolar level. Moreover, most of existing UCNP-based probes are only able to detect short-chain oligonucleotides, which are not suitable for detection of long-chain oligonucleotides in many real applications. In this work, we introduced a new UCNP-based fluorescence resonance energy transfer (FRET) nanoprobe design composed of NaGdF4:Yb3+, Er3+@NaGdF4 core-shell UCNPs (csUCNPs) linking with Au–Au dimer to detect long-chain oligonucleotides of SARS-CoV-2 N-gene. Compared with typical single gold nanoparticles (AuNPs) in FRET biosensors, our theoretical investigation shows that a stronger electromagnetic field is generated in the Au–Au dimer where the plasmon resonance can enhance FRET efficiency and increase the working distance. Thus, the synergetic effect of plasmonic resonance and FRET enables a greater quenching efficiency (QE) of Au–Au dimer to UCNPs, which leads to more remarkable upconversion luminescence (UCL) recovery for each target gene recognition. Importantly, our design significantly improved the limit of detection (LOD) to attomolar level, with a linear response ranging from 2 aM to 2 fM. Moreover, the clinical detection with inactivated SARS-CoV-2 samples was successfully performed with excellent specificity within 30 min using the developed UCNPs biosensors incorporated with Au–Au dimer. This UCNP biosensor based on Au–Au dimer strategy with ultra-sensitivity and good selectivity opens a new path for clinical diagnosis without target amplification and plays an instructive role in other virus diagnosis.

Immunochromatographic assay integrated smartphone-based device for simultaneous detection of multiple mycotoxins using core-shell up-conversion nanoparticles

Universal contamination and synergistic toxicity of multiple mycotoxins in foodstuffs have become a challenge in food safety, posing a serious threat to human and animal health. Herein, we developed a multiple immunochromatography assay (mICA) integrating a smartphone device with core-shell up-conversion nanoparticles (UCNPs) for simultaneous detection of deoxynivalenol (DON), aflatoxin B1 (AFB1) and zearalenone (ZEN) in cereals. The limits of detection for DON, AFB1, and ZEN could be quickly obtained within 10 min, with values of 0.25 ng/mL, 0.05 ng/mL, and 0.1 ng/mL, respectively. Furthermore, the practicability and repeatability of the core-shell UCNPs-mICA were successfully evaluated by detecting the recoveries of DON, AFB1 and ZEN in corn and wheat under the optimal sample extraction. The results obtained by the smartphone-based UCNPs-mICA were consistent with those by high-performance liquid chromatography, demonstrating the advantage of being faster and more portable. Due to its high sensitivity, high specificity, low cost, and portability, the proposed core-shell UCNPs-mICA integrated with a smartphone-based device provides significant potential prospects in the rapid screening of mycotoxins.

Photosensitizing deep-seated cancer cells with photoprotein-conjugated upconversion nanoparticles

To resolve the problem of target specificity and light transmission to deep-seated tissues in photodynamic therapy (PDT), we report a cancer cell-targeted photosensitizer using photoprotein-conjugated upconversion nanoparticles (UCNPs) with high target specificity and efficient light transmission to deep tissues. Core-shell UCNPs with low internal energy back transfer were conjugated with recombinant proteins that consists of a photosensitizer (KillerRed; KR) and a cancer cell-targeted lead peptide (LP). Under near infrared (NIR)-irradiating condition, the UCNP-KR-LP generated superoxide anion radicals as reactive oxygen species via NIR-to-green light conversion and exhibited excellent specificity to target cancer cells through receptor-mediated cell adhesion. Consequently, this photosensitizing process facilitated rapid cell death in cancer cell lines (MCF-7, MDA-MB-231, and U-87MG) overexpressing integrin beta 1 (ITGB1) receptors but not in a cell line (SK-BR-3) with reduced ITGB1 expression and a non-invasive normal breast cell line (MCF-10A). In contrast to green light irradiation, NIR light irradiation exhibited significant PDT efficacy in cancer cells located beneath porcine skin tissues up to a depth of 10 mm, as well as in vivo tumor xenograft mouse models. This finding suggests that the designed nanocomposite is useful for sensing and targeting various deep-seated tumors.

A new ratiometric fluorescence nanosensor based on NaYF4:3%Er@NaYF4 upconversion nanoparticles for sensitive determination of Rose Bengal in water

Rose Bengal (RB) is used as a sensitizer in ambient water due to its property of catalyzing the production of singlet oxygen (1O2). However, this property also brings phototoxicity and carcinogenicity. The NaYF4:3%Er@NaYF4 core-shell upconversion nanoparticles (UCNPs) with higher upconversion efficiency was synthesized to detect RB in ambient water. Due to fluorescence resonance energy transfer (FRET) between RB and UCNPs, the upconversion fluorescence at 538 nm emitted by UCNPs was quenched by the RB, while the emission at 566 nm of RB raised. In the best conditions, the ratiometric emission intensity F566/F538 was positively proportional to RB concentration and the linear range was 0.04–15.0 μg·mL−1 (R2 = 0.996). The detection limit (S/N = 3) of RB was 2.46 ng·mL−1. The recoveries ranged from 99.0% to 105.6% (relative standard deviation 0.97–3.24%, n = 3) in tap water and 100.3%–104.9% (relative standard deviation 0.66–1.94%, n = 3) in lake water. This proposed method exhibits lower detection limit and larger linear, which possesses practical application value to the detection of RB in water.

Volumetric Nanocrystal Lattice Reconstruction through Dynamic Metal Complex Docking.

Vacancies pose a major challenge in the production of high-quality crystals, particularly at the nanoscale. To address this problem, we report a convenient strategy that involves volumetric lattice reconstruction and dynamic metal complex docking to produce ultrasmall (10 nm) and bright core-shell upconversion nanoparticles (UCNPs). This strategy involves the formation of lanthanide ion-oleic acid complexes during postannealing in solution, which effectively removes vacancies in nanocrystals. The removal of vacancies restricts the diffusion of lanthanide sensitizers and emitters within the core, thus minimizing surface quenching. Our volumetric lattice reconstruction strategy provides fundamental insights into lattice engineering and presents a general strategy for purifying functional nanocrystals for applications in fields such as single-molecule tracking, quantum optics, energy conversion, and others.

Enhanced thermometry sensitivity in upconversion nanoparticles via near-field manipulation

Recently, nanoscale thermometry has attracted extensive attention. Here, we present an innovative approach to enhance the sensitivity of upconversion nanoparticles for thermometry through near-field manipulation. This method involves a composite structure consisting of photonic crystals and upconversion nanoparticles, with the near-field of the nanoparticles manipulated by tuning the absorption of the photonic crystals. The fluorescence intensity ratio (540nm/520 nm) of 4H11/2 and4S3/2 states of upconversion nanoparticles doped with Er3+ ions is sensitive to temperature change and employed as a temperature indicator that satisfies Boltzmann thermal equilibrium. The composite structure exhibited a relative thermometry sensitivity of 21.9 × 10−3 K−1 at 298 K, representing a significant improvement over pure core-shell upconversion nanoparticles with a 63.43% increase in relative sensitivity and a 675% increase in absolute sensitivity. This finding demonstrates the potential of our approach for advancing nanoscale thermometry.

Brightening heavily doped upconversion nanoparticles by tuning characteristics of core-shell structures

Heavily doped upconversion nanoparticles (UCNPs) potentially have exceptional photon upconversion abilities that are promising for diverse applications, such as lasing and super-resolution microscopy. However, heavily doped UCNPs typically can only offer mediocre upconversion luminescence intensity, and there still lacks general guidelines for the design and synthesis of heavily doped UCNPs. Herein, in order to boost the upconversion luminescence of heavily doped UCNPs, we studied the influence of characteristics of the core–shell structure on heavily doped UCNPs’ upconversion luminescence. We find that some empirical guidelines derived from conventional UCNPs are not suitable for heavily doped UCNPs. Using NaYbF4:Tm@NaYF4 core–shell UCNPs with a high concentration of Yb3+ as a representative, our studies reveal that a rather thick inert NaYF4 shell is needed to protect the UCNPs from surface quenching, and the upconversion luminescence may undergo the cooperative sensitization process, which should be due to the highly concentrated Yb3+ dopant. In addition, the upconversion luminescence of heavily doped NaYbF4:Tm UCNPs exhibits no obvious dependence on the type of inert shell. Furthermore, our results show that confining both Yb3+ and Tm3+ dopants in a thin layer (known as the δ-doping strategy) does not work well in the heavily doped UCNPs. Accordingly, we propose a NaYbF4:Tm@NaYbF4@NaYF4 core–shell–shell structure to enhance the luminescence of heavily doped UCNPs, by weakening the dissipation of excitation energy and strengthening the absorption. These findings should be helpful to establish general design principles for developing the brightest possible UCNPs that can meet the requirements of various applications.

A strategy for the accurate detection of glucose in human serum based on the IFE effect of up-transformed nanoparticles

Here, the inner filter effect (IFE) was applied to construct a “turn off” mode up-conversion fluorescence and colorimetric dual-reading detection platform consisting of the chromogenic substance p-phenylenediamine (PPD) and NaYF4:Yb/Er@NaYF4 core–shell up-conversion nanoparticles (UCNPs) for the detection of glucose and hydrogen peroxide (H2O2) with high sensitivity and selectivity. In this strategy, hydrogen peroxide is produced in the process of glucose oxidation by catalyzing glucose oxidase (GOx). PPD is oxidized by H2O2 under the action of horseradish peroxidase (HRP), resulting in the transformation into its oxidation product PPDox, whose absorption peak coincides with the emission peak of UCNP at 540 nm, which can significantly quench the fluorescence of UCNP. The quenching efficiency is related to PPDox production, so the relationship between the glucose content and the fluorescence changes of UCNP can be established to realize the sensitive detection of glucose. UCNPs modified by –COOH and the oxidation product of PPD were negatively charged, which increased the distance between donor and recipient due to electrostatic repulsion. It was not conducive to the occurrence of distance-dependent fluorescence resonance energy transfer (FRET), which was also verified by fluorescence lifetime test. Under the optimal experimental conditions, the linear ranges of hydrogen peroxide and glucose were 2.5 ∼ 50 and 5 ∼ 80 μmol/L with the detection limit (LOD) of 0.32 and 0.83 μmol/L, respectively, which were lower than of some reported approaches. Furthermore, the system could be applied to the detection of glucose in actual serum sample and the results were consistency of commercial glucose meters which indicated that the protocol was reliable and potential applications for clinical diagnosis.

A dual-targeting near-infrared biomimetic drug delivery system for HBV treatment.

Hepatitis B virus (HBV) infection is a serious global public health threat. It remains elusive to achieve a functional HBV cure with currently available antivirals. Herein, a photo-responsive delivery vehicle composed of Nd3+ -sensitized core-shell upconversion nanoparticle (UCNP), mesoporous silica nanoparticle (MSN), antisense oligonucleotides (ASOs), and capsid-binding inhibitor C39 was established, which was named UMAC according to the initials of its components. Subsequently, the as-synthesized delivery vehicle was encapsulated by β- D-galactopyranoside (Gal) modified red blood cell (RBC) membrane vesicles, which enabled precise targeting of the liver cells (UMAC-M-Gal). Both in vitro and in vivo experiments demonstrated that this biomimetic system could successfully achieve controlled drug release under light conditions at 808 nm, leading to effective suppression of HBV replication in this dual-targeted therapeutic approach. Together, these results substantiate the system has huge prospects for application to achieve functional HBV cure, and provides a promising novel strategy for drug delivery.

Plasmonic Chiral Metasurface-Induced Upconverted Circularly Polarized Luminescence from Achiral Upconversion Nanoparticles.

Chirality induction, transfer, and manipulation have aroused great interest in achiral nanomaterials. Here, we demonstrate strong upconverted circularly polarized luminescence from achiral core-shell upconversion nanoparticles (UCNPs) via a plasmonic chiral metasurface-induced optical chirality transfer. The Yb3+-sensitized core-shell UCNPs with good dispersity exhibit intense upconversion luminescence of Tm3+ and Nd3+ through the energy transfer process. By spin-coating the core-shell UCNPs on this chiral metasurface, strong enhancement and circular polarization modulation of upconversion luminescence can be achieved due to resonant coupling between surface plasmons and upconversion nanoparticles. In the UCNPs-on-metasurface composite, a significant upconversion luminescence enhancement can be achieved with a maximum enhancement factor of 32.63 at 878 nm and an overall enhancement factor of 11.61. The luminescence dissymmetry factor of the induced upconverted circularly polarized luminescence can reach 0.95 at the emission wavelength of 895 nm. The UCNPs-on-metasurface composite yields efficient modulation for the emission intensity and polarization of UCNPs, paving new pathways to many potential applications in imaging, sensing, and anticounterfeiting fields.

RuNO-Thnl-loaded nanoplatform excited by 808 nm near-infrared light for gas release

Förster energy resonance transfer (FRET) refers to a type of non-radiative energy transfer between two chromophores. In addition to the distance between the donor and acceptor, it depends on the extent of overlap between the fluorescence spectrum of the donor and the absorption spectrum of the acceptor. Based on the principle of FRET, in this study, NIR-responsive nanoplatforms comprising up-conversion nanoparticles (UCNPs)@mSiO2&RuNO-Thnl were designed for the targeted and controllable release of NO. First, core–shell UCNPs were prepared by the thermal decomposition method and then coated with a mesoporous silica layer by surface modification. The prepared UCNPs@mSiO2 was excited by NIR at 808 nm, which avoided the overheating of Yb3+ and increased the penetration depth; in addition, it imparted drug-loading capability and biocompatibility to the UCNPs. Subsequently, RuNO-Thnl and UCNP@mSiO2 were combined using van der Waals forces. Furthermore, UCNPs@mSiO2 converted 808 nm NIR laser irradiation into ultraviolet light or visible light, thereby exciting RuNO-Thnl for the effective local release of NO. The results showed that this NO release platform can release 0.0012–0.0037 μmol/mL of NO gas when the concentration of the solution containing the nanoplatform is in the range of 0.15–0.8 mg/mL, allowing for concentration-controlled NO release on demand. Importantly, the temperature changes generated during the conversion process were not harmful to cells and tissues. This targeted and controlled release approach has broad application prospects in NO-based medical therapy.

An upconversion biosensor based on DNA hybridization and DNA-templated silver nanoclusters for the determination of acrylamide

Acrylamide is widely present in many fried and baked foods, that has been proved as potentially carcinogenic to humans. In this work, a novel biosensor using core-shell upconversion nanoparticles (CSUCNPs) with aptamer as recognized element was designed for the determination of acrylamide. The principle of this work was based on the fluorescence resonance energy transfer (FRET) process from CSUCNPs to silver nanoclusters (AgNCs). Whereas the binding between acrylamide and the aptamer disturbed the DNA structure and inhibited the synthesis of AgNCs, which induced a higher fluorescence intensity. Under the optimal conditions, a low limit of detection (LOD) was calculated as 1.13 nM in the range of 1–105 nM. This biosensor was further applied in the spiked food samples to validate the applicability that recoveries were at the range of 78.52–117.09% with a relative standard deviation of 1.54–10.46%. The approach was compared with the standard HPLC method in great agreement (P ＞ 0.05).

An optical strategy for detecting hypochlorite in vitro and cells with high selectivity and stability based on a lanthanide-doped upconversion probe.

The excessive use of sodium hypochlorite disinfectant for preventing COVID-19 can be harmful to the water environment and humans. More importantly, owing to hypochlorite being a biomarker of immune responses in living organisms, its abnormal production can damage nucleic acids and protein molecules, eventually causing many diseases (even cancer). Exploring a reliable, rapid, and non-invasive method to monitor the hypochlorite level in vitro and in cells can be significant. Herein, we report a novel ratiometric fluorescence sensing strategy based on Astrazon Brilliant Red 4G dye-sensitized NaGdF4:Yb3+, Er3+@NaYF4 core-shell upconversion nanoparticles (UCNPs@ABR 4G). Based on the combination mechanism of the fluorescent resonant energy transfer effect (FRET) and redox, a linear model of fluorescence intensity ratio and hypochlorite concentration was constructed for a fast response and high selectivity monitoring of hypochlorite in vitro and in vivo. The detection limit was calculated to be 0.39 μM. In addition, this sensing strategy possessed good stability and circularity, making it valuable both for the quantitative detection of hypochlorite in water and for the visualization of intracellular hypochlorite. The proposed optical probe is promising for the efficient and stable non-invasive detection of hypochlorite.

Full shell coating or cation exchange enhances luminescence

Core-shell structure is routinely used for enhancing luminescence of optical nanoparticles, where the luminescent core is passivated by an inert shell. It has been intuitively accepted that the luminescence would gradually enhance with the coverage of inert shell. Here we report an “off-on” effect at the interface of core-shell upconversion nanoparticles, i.e., regardless of the shell coverage, the luminescence is not much enhanced unless the core is completely encapsulated. This effect indicates that full shell coating on the luminescent core is critical to significantly enhance luminescence, which is usually neglected. Inspired by this observation, a cation exchange approach is used to block the energy transfer between core nanoparticle and surface quenchers. We find that the luminescent core exhibits enhanced luminescence after cation exchange creates an effective shell region. These findings are believed to provide a better understanding of the interfacial energy dynamics and subsequent luminescence changes.

Continuous synthesis of ultrasmall core-shell upconversion nanoparticles via a flow chemistry method

Continuous synthesis of ultrasmall core-shell upconversion nanoparticles via a flow chemistry method