Up-conversion luminescence and temperature sensing properties of Ho3+-, Tm3+-, and Yb3+-codoped Bi2WO6 materials in a water environment.

A series of x%Ho3+, 5 %Tm3+, y%Yb3+:Bi2WO6 (x = 0, 0.5, 1, 3, 5; y = 0.5, 1, 3) luminescent materials was prepared using a high-temperature solid-phase method. The microstructure, up-conversion luminescence, and temperature sensing properties of the synthesized powders were analyzed. X-ray diffraction patterns revealed that doping with Ho3+, Tm3+, and Yb3+ ions at certain concentrations did not affect the orthorhombic crystal structure of the Bi2WO6 host. Scanning electron microscopy revealed that the morphology of the sample consisted of lumpy particles with a particle size range of 1-5 µm and agglomeration. SEM mapping and energy-dispersive X-ray spectroscopy analyses revealed that each element was relatively uniformly distributed on the particle surface. Under 980 nm excitation (380 mW), the strongest luminescence of the sample was obtained when both Ho3+ and Yb3+ doping concentrations were 1 %. Compared with the luminescence of the 5 %Tm3+ and 1 %Yb3+:Bi2WO6 sample, with increasing Ho3+ concentrations, the luminescence intensity of Tm3+ was first enhanced and subsequently weakened, whereas the luminescence of Ho3+ was significantly weakened, which indicates the positive energy transfer from Ho3+ â†’ Tm3+. At 980 nm (80-380 mW), for the 1 %Ho3+, 5 %Tm3+, and 1 %Yb3+:Bi2WO6 sample, the 538 nm, 545 nm, 660 nm, and 804 nm emission peaks originated from the two-photon absorption. FIR660 nm/804 nm, FIR545 nm/804 nm, and FIR538 nm/804 nm were used to characterize the temperature and corresponded to temperature sensitivities Sr of 0.0046 K-1, 0.022 K-1 and 0.024 K-1 at 573 K, respectively. At 498 K, the minimum temperature resolution δT values were 0.03384 K, 0.03203 K and 0.04373 K. When the temperature increased from 298 K to 573 K, the powder sample luminescence gradually shifted from the yellow-green region to the red region. The results of environmental discoloration and thermochromic performance tests indicate that this sample has potential application in optical anti-counterfeiting. FIR804 nm /660 nm and FIR804 nm /538 nm were obtained for the 40 NTU turbidity suspension under identical excitation conditions. At 298 K, for the 40 NTU turbidity sample, the maximum Sr values were 0.0197 K-1 and 0.0405 K-1; at 340 K, the minimum temperature resolutions δT values were 0.54037 K and 0.66237 K. When the temperature decreased from 340 K to 298 K, the luminescence of the 40 NTU suspension samples gradually shifted from the yellow region to the green region.

Novel multi-mode anti-counterfeiting encryption material of CaAl12O19:Eu, Er with multi-color down-conversion luminescence, up-conversion luminescence, dynamic luminescence, and photochromism.

Multi-mode dynamic anti-counterfeiting materials can provide complex anti-counterfeiting performance and ensure the anti-counterfeiting strategy becomes more secure. Herein, a new type of multi-mode anti-counterfeiting encryption material of CaAl12O19:Eu, Er with different Er doping concentration was developed by sol-gel method. Interestingly, the CaAl12O19:Eu, Er phosphor and its composite have multi-mode anti-counterfeiting characteristics of multi-color down-conversion luminescence, up-conversion luminescence, dynamic luminescence, and photochromism. Effect of different Er doping concentration on the down-conversion luminescence, up-conversion luminescence, dynamic luminescence, and photochromism of CaAl12O19:Eu, Er was systematically investigated, and the relevant mechanisms were discussed. These anti-counterfeiting features can be simultaneously applied in both bright and dark fields, which can achieve high-level anti-counterfeiting in both spatial and temporal dimensions. The CaAl12O19:Eu, Er phosphors cannot be easily replaced by other materials with the same anti-counterfeiting properties. They display good application foreground in the field of anti-counterfeiting encryption.

Light-Responsive Smart Nanoliposomes: Harnessing the Azobenzene Moiety for Controlled Drug Release under Near-Infrared Irradiation.

The azobenzene moiety is an intriguing structure that deforms under UV and visible light, indicating a high potential for biomedical applications. However, its reaction to UV radiation is problematic because of its high energy and low tissue penetration. Unlike previous research on azobenzene structures in photoresponsive materials, this study presents a novel method for imparting photostimulation-responsive properties to liposomes by incorporating the azobenzene moiety and extending the light wavelength with up-conversion nanoparticles. First, the azobenzene structure was incorporated into a phospholipid molecule to create Azo-PSG, which could spontaneously form vesicle assemblies in aqueous solutions and isomerizes within 1 h of light exposure. Furthermore, orthogonal up-conversion nanoparticles with a core-shell structure were created by sequentially growing lanthanide rare earths in the shell layer, which efficiently converts near-infrared light into ultraviolet (400 nm) and blue-green (540 nm) light. Combining these core-shell structured up-conversion nanomaterials with Azo-PSG molecules resulted in the creation of a near-infrared light-responsive smart nanoliposome system. Under near-infrared light irradiation, UCNPs emit UV and blue-green light, causing conformational changes in Azo-PSG molecules that allow drug release within 6 h. The reversible structural shift of Azo-PSG in response to light stimulation holds enormous promise for improving drug release techniques. This novel technique also expands the usage of UV-responsive compounds beyond their constraints of low penetration and high biotoxicity, allowing for rapid medication release under NIR light.

Sodium Assists Controlled Synthesis of Cubic Rare-Earth Oxyfluorides Nanocrystals for Information Encryption and Near-Infrared-IIb Bioimaging.

Rare-earth oxyfluoride (REOF) colloidal nanocrystals (NCs) suffer from a low photoluminescence efficiency due to their small size with poor crystallinity and a detrimental surface quenching effect. Herein, we introduce an innovative approach that involves doping sodium ions into REOF NCs to produce monodisperse, size-controllable, well-crystallized, and highly luminescent colloidal REOF core/shell NCs. The Na+ doping allows for successfully synthesizing the cubic REOF NCs with a tunable size from 6 to 30 nm. Further fabrication of the core/shell NCs doped with Na+ results in enhancements up to 1062 (Ho3+), 1140 (Er3+), and 2212 (Tm3+) folds in upconversion luminescence and 17.7 folds (Er3+) in downconversion luminescence compared to that of core/shell NCs without doping Na+ ions. These NCs were subsequently developed into multicolor luminescent inks, demonstrating significant potential application for information security, and used for near-infrared-IIb (NIR-IIb) (1500-1700 nm) in vivo imaging, which exhibits a high-resolution in vivo dynamic imaging capability with a signal-to-noise ratio of 5.28. These results present the way to the controlled synthesis of efficient luminescent cubic LuOF: RE3+/LuOF core/shell NCs, expanding the toolkit of rare-earth doped NCs in diverse applications such as advanced encoding encryption, varied fluorescence imaging, and biomedicine.

Unlocking nature's brilliance: using Antarctic extremophile Shewanella baltica to biosynthesize lanthanide-containing nanoparticles with optical up-conversion.

Both lanthanide-containing and fluorine-containing nanomaterials present challenging targets for microbial biosynthesis because these elements are toxic to most bacteria. Here, we overcome these challenges by using an Antarctic Shewanella baltica strain that tolerates these elements and report the first biosynthesis of lanthanide-doped fluoride nanoparticles (NPs) from them. NaYF4 NPs doped with Er3+/Yb3+ are prototypical lanthanide-based upconverting nanoparticles (UCNPs) with upconverted luminescence at visible wavelengths under infrared excitation. However, their synthesis employs high precursor concentrations, organic solvents, and elevated temperatures. Microbial biosynthesis offers a greener alternative but has not been explored for these materials. Here, we harness an extremophile S. baltica strain to biosynthesize UCNPs at room temperature, based upon its high tolerance for fluoride and lanthanide ions and the observation that tolerance of lanthanides increased in the presence of fluoride. Our biosynthesis produces electron-dense nanostructures composed of Na, Y, F, Yb, and Er in the bacterial periplasm, adhered to the outer cell membrane, and dispersed extracellularly, which exhibited up-converted emission under 980 nm excitation. This suggests that extracellular or periplasmic mineralization of lanthanides as fluorides protects the bacteria from lanthanide toxicity. Subsequent heating both enhanced upconverted emission from UCNPs and allowed observation of their crystallinity in transmission electron microscopy (TEM). This work establishes the first biosynthesis of NaYF4:Yb: Er UCNPs, advancing both nanotechnology and biotechnology.

Large Dynamic Range Spectral Measurement in Terahertz Region Based on Frequency Up-Conversion Detection via OH1 Crystal.

Terahertz spectroscopy systems, which integrate terahertz sources and detectors, have important applications in many fields such as materials science and security checking. Based on highly sensitive frequency up-conversion detection, large dynamic range spectral measurements in a terahertz region are reported. Our system realized the detection sensitivity at a 10 aJ level with a 2-(3-(4-hydroxystyryl)-5,5-dime-thylcyclohex-2-enylidene) malononitrile (OH1) crystal and a dynamic range up to seven orders. Based on this system, we verified the validity of the spectral measurement with tests which were conducted on monohydrate glucose, anhydrous glucose and mixed tablet samples with a thickness of 0.8 mm in 1~3 THz, respectively. Also, a mini coppery elbow tube with an inner diameter of 1 mm was used for the transmission of a terahertz wave to simulate some strip biological tissue samples. By allowing terahertz to transmit through this tube filled with 0.5 g glucose powder, we successfully obtained the absorption spectrum with a minimum transmittance at the absorption peak in the order of 10-4.

Host Engineering of Deep-Blue-Fluorescent Organic Light-Emitting Diodes with High Operational Stability and Narrowband Emission.

The realization of highly operationally stable blue organic light-emitting diodes (OLEDs) is a challenge in both academia and industry. This paper describes the development of anthracene-dibenzofuran host materials, 2-(10-(naphthalen-1-yl)anthracen-9-yl)naphtho[2,3-b]benzofuran (Host 1) and 2-(10-([1,1'-biphenyl]-2-yl)anthracen-9-yl)naphtho[2,3-b]benzofuran (Host 2), namely for use in the emissive layer of an OLED stack. A multiple-resonance thermally activated delayed serves as the blue fluorescence emitter and exhibits an initial luminance of 1000 cd m-2 and long operational stability (i.e., time to decay to 90% of initial luminance) of 249 h. Furthermore, a deep-blue OLED with an optimized top-emitting architecture with a high current efficiency of 154.3 cd A-1, is fabricated and calibrated to a Commission International de l'Éclairage y chromaticity coordinate of 0.048. Moreover, the emission spectrum of this OLED has a narrowband peak at 476 nm with a full width at half maximum (FWHM) of 16 nm. This work provides valuable insights into the design of anthracene-based host materials and highlights the importance of host optimization in improving the operational stability of OLEDs.

Modeling and Experimental Study of Vibration Energy Harvester with Triple-Frequency-Up Voltage Output by Vibration Mode Switching.

Conventional wireless sensors rely on chemical batteries. Replacing or charging their batteries is tedious and costly in some situations. As usable kinetic energy exists in the environment, harvesting vibration energy and converting it into electrical energy has become a hotspot. However, the power output capability of a conventional piezoelectric energy harvester (PEH) is limited by its low operational frequency. This paper presents a new mechanism for achieving continuous triple-frequency-up voltage output in a PEH. The proposed system consists of a slender piezoelectric cantilever with two short cantilever-based stoppers. The piezoelectric cantilever undergoes a pure bending mode without contacting the stoppers. In addition, the beam switches into a new vibration mode by contacting the stoppers. The vibration modes switching yields reverses the signs of voltage outputs, inducing triple-frequency-up voltage output. Analytical and experimental investigations are presented, and it is shown that a significant triple-frequency up-conversion of the voltage output can be obtained over a wide frequency range. A peak power output of 3.03 mW was obtained. The proposed energy harvester can support a wireless sensor node.

Cytotoxic effects of NIR responsive chitosan-polymersome layer coated melatonin-upconversion nanoparticles on HGC27 and AGS gastric cancer cells: Role of the ROS/PI3K/Akt/mTOR signaling pathway.

In this study, a formulation of NaGdF4:Tm/Er@NaGdF4 (core@shell) UCNPs loaded with melatonin drug was synthesized. The novel melatonin-loaded UCNPs were then encapsulated within NIR-responsive biopolymeric chitosan (CS) based polymersome and investigated against gastric cancer (HGC27 & AGS) cells. The photolysis of the ONB moiety and disruption of the disulfide linkage in the polymersome induced by NIR light facilitated by the NaGdF4:Tm/Er@NaGdF4 UCNPs and GSH results in an increased release of melatonin drug. The DLS and zeta potential measurements exhibit a reduced particle size (21.9 ± 3.56 nm) and a low zeta potential (17.91 mV). Furthermore, drug release profiles demonstrated superior melatonin drug release (79.78 %) at pH 5.0 for CS-polymersome-coated melatonin-UCNPs resembling the Hixson-Crowell model. Remarkably, CS-polymersome-coated melatonin-UCNPs exhibit excellent anti-proliferative properties for HGC27 (IC50 = 0.096 µM) and AGS (IC50 = 0.16 µM) cancer cells. The flow cytometry data demonstrate a significant elevation in ROS levels which promoted cell death in both HGC-27 and AGS cells. The observed cell mortality in HGC-27 and AGS cells is primarily caused by the destruction of the nucleus, mtDNA, rupture of disulfide (R-S-S-R) bonds, and nuclear DNA. Contrarily, L929 and HUVECs cells incubated with CS-polymersome coated melatonin-UCNPs (100 µg/mL) reveal a notable cell viability of 88.7 % and 93 % indicating superior biocompatibility. The western blotting analysis revealed the induction of autophagy by CS-polymersome-coated melatonin-UCNPs which subsequently led to apoptosis by regulating the ROS/PI3K/Akt/mTOR molecular signaling pathway.

Up-Conversion Luminescence and Optical Temperature Sensing Properties of NaLuF4:Yb3+/Ho3+ Micron-Sized Crystals at Low Temperature.

Non-contact temperature sensors utilising the fluorescence intensity ratio and the unique up-conversion (UC) luminescence of rare-earth ions have numerous benefits; however, their operational temperature range has remained limited. In this study, NaLuF4:Yb3+/Ho3+ samples were prepared by the hydrothermal method. The samples exhibited exceptional UC luminescence properties at low temperatures. The intensity of the green emission (with peak wavelengths of 540 and 546 nm) gradually decreased with increasing temperature, and the green emissions showed a unique change at low temperatures. In addition, we studied the dependence of the UC luminescence intensity on the excitation power and the variation in the decay lifetime with temperature. The experiments revealed excellent luminous performance and significantly enhanced sensitivity at low temperatures; the maximum absolute sensitivity Sa and relative sensitivity Sr of the 540 and 546 nm thermally coupled energy levels were 1.02% and 0.55% K-1, respectively. The potential temperature sensing properties of Yb3+/Ho3+-co-doped NaLuF4 makes it suitable for temperature sensing applications at temperatures as low as 30 K. This study offers a novel approach for the advancement of temperature sensing technology at low temperatures.

Er 3 + , Nd 3 + , Tm 3 + : Up-conversion in Lead Borophosphate Glasses for Visible Emission.

To investigate the role of PbO as a former or a modifier and effect of its compositional variation on the physical, structural and optical properties, lithium lead borophosphate glasses were synthesized by melt quenching technique. For the physical properties of the prepared glasses, density was measured using the Archimedes principle, which showed an increasing trend from 3.13 to 4.51 with increasing concentrations of lead oxide. Additionally, other physical parameters were calculated based on the measured density values. The structural analysis were performed through X-ray diffraction and Fourier transform infrared spectroscopy. Lack of sharp and characteristic peaks in the XRD spectra confirmed the non crystalline nature of the prepared glasses. Structural units due to PbO, P 2 O 5 and B 2 O 3 were identified from the FTIR spectra. Ultraviolet-visible absorption spectroscopy was performed for optical properties and increase in the indirect band gap from 4.80 eV to 4.90 eV was observed. One glass sample was chosen for doping of erbium, neodymium, thulium and ytterbium, for study of their up-conversion properties. The UV-Vis-NIR absorption spectra of erbium, neodymium, and thulium samples were recorded, and wavelength of 980 nm was chosen for excitation. Ytterbium, acting as a sensitizer, facilitated the conversion of the excitation infrared light into visible light. Upon excitation at 980 nm, the erbium-doped sample emitted light at 520 nm, 547 nm, and 665 nm, utilizing excited state up-conversion (ESA) and energy transfer up-conversion (ETU) mechanisms. Similarly, the neodymium-doped sample emitted at 542 nm, 602 nm, and 660 nm, while the thulium-doped sample emitted at 488 nm, 521 nm, and 649 nm. The results of up-conversion indicate that rare earth-doped lithium lead borophosphate glasses are excellent hosts for up-conversion processes.

Rare-earth-free up and down-conversion dual-emission carbon dots for Cu2+ sensing.

In this work, up- and down-conversion dual-emission CDs without rare-earth (UD D-CDs) were synthesized using RhB and 1,4-Diaminoanthraquinone as precursors. The synthesized UD D-CDs exhibited dual emissions at 496 and 580 nm under 260 and 865 nm excitation, respectively. The fluorescence emission mechanism, including contributions from carbon nuclei, surface states, molecular states, and internal defect states, was discussed through the separation and purification of UD D-CDs. Based on the interaction between UD D-CDs and copper ions (Cu2+), a dual-mode ratio fluorescence probe was developed to detect and quantify Cu2+. The up-conversion ratio fluorescent probe shows a linear range of 0.0500-15.0 µM, with a detection limit as low as 2.76 nM. This method has been successfully applied to detecting Cu2+ in human serum and has potential applications in biochemical analysis and biological imaging. The successful preparation of up-conversion fluorescent carbon dots without rare earth elements and the ability to perform low-damage detection in high-background biological samples provide a new approach to constructing non-rare earth up-conversion probes.

Tunable Intracavity Coherent Up-Conversion with Giant Nonlinearity in a Polar Fluidic Medium.

The study has demonstrated a novel microcavity-based flexible photon up-conversion system using second harmonic generation (SHG) from a polar nematic fluidic medium doped with a laser dye. The idea is based on coherent light generation via stimulated emission (lasing) and simultaneous frequency doubling inside a microcavity. The polar nematic fluid equips very high even-order optical nonlinearity due to its polar symmetry and large dipole moment along the molecular long axis. At the same time, its inherent fluidic nature allows to easily functionalize the media just by doping, in the present case, with an emissive laser dye. The demonstrated system exhibits a giant nonlinear optical response to input light, while enabling spectral narrowing and multiple-signal output of up-converted light, which is not attainable through the simple SH-conversion of input light. Furthermore, the susceptibility of the liquid crystal offers dynamic modulation capabilities by an external stimulus, such as signal switching by the application of electric field or wavelength tuning through temperature variation. Such a brand-new type of simple coherent flexible up-conversion system must be promising as a new principle for easily accessible and down-scalable wavelength conversion devices.

Enhanced SWIR Light Detection in Organic Semiconductor Photodetectors through Up-Conversion of Mid-Gap Trap States.

Shortwave-infrared (SWIR) photodetectors are vital for many scientific and industrial applications including surveillance, quality control and inspection. In recent decades, photodetectors based on organic semiconductors have emerged, demonstrating potential to add real value to broadband and narrowband imaging and sensing scenarios, where factors such as thermal budget sensitivity, large area aperture necessity, cost considerations, and lightweight and conformal flexibility demands are prioritized. It is now recognized that the performance of organic photodetectors (OPDs), notably their specific detectivity, is ultimately limited by trap states, universally present in disordered semiconductors. This work adopts an approach of utilizing these mid-gap states to specifically create a SWIR photo-response. To this end, this work introduces a somewhat counter-intuitive approach of "trap-doping" in bulk heterojunction (BHJs) photodiodes, where small quantities of a guest organic molecule are intentionally incorporated into a semiconducting donor:acceptor host system. Following this approach, this work demonstrates a proof-of-concept for a visible-to-SWIR broadband OPD, approaching (and, to some extent, even exceeding) state-of-the-art performance across critical photodetector metrics. The trap-doping approach is, even though only a proof-of-concept currently, broadly applicable to various spectral windows. It represents a new modality for engineering photodetection using the unconventional strategy of turning a limitation into a feature.

Synthesis of Up-Conversion CaTiO3: Er3+ Films on Titanium by Anodization and Hydrothermal Method for Biomedical Applications.

The present study investigates the effects of Er3+ doping content on the microstructure and up-conversion emission properties of CaTiO3: Er3+ phosphors as a potential material in biomedical applications. The CaTiO3: x%Er3+ (x = 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0%) films were synthesized on Ti substrates by a hydrothermal reaction at 200 °C for 24 h. The SEM image showed the formation of cubic nanorod CaTiO3: Er3+ films with a mean edge size value of (1-5) µm. When excited with 980 nm light, the CaTiO3: Er3+ films emitted a strong green band and a weak red band of Er3+ ions located at 543, 661, and 740 nm. The CaTiO3: Er3+ film exhibited excellent surface hydrophilicity with a contact angle of ~zero and good biocompatibility against baby hamster kidney (BHK) cells. CaTiO3: Er3+ films emerge as promising materials for different applications in the biomedical field.

High-Performance Up-Conversion Photodetectors with Zero-Barrier Interconnection via Self-Assembled Surface Dipoles.

The performance of lead sulfide (PbS) quantum-dot-based up-conversion photodetectors is greatly limited owing to a large potential barrier at the interconnection layer between the photodetecting (PD) unit and light-emitting (LED) unit. Thus, very high driving voltage is required, rendering high energy consumption and poor working stability. By introducing azetidinium iodide (AzI) at the PD/LED interface, zero-barrier interconnection was achieved for the PbS-based infrared up-conversion photodetectors. The turn-on voltage under infrared illumination was greatly reduced to 1.2 V and a high photon-to-photon conversion efficiency (ηpp) of ∼3% was obtained at 3 V, showing a 10-fold enhancement compared to those previously reported devices. The mechanism for the regulation of interface energy level alignments was related to the self-assembly of the AzI dipole molecules, resulting from the van der Waals force between the S atoms in the ligands of PbS and the protonated H atoms around N atoms in AzI.

A Frequency Up-Conversion Piezoelectric Energy Harvester Shunted to a Synchronous Electric Charge Extraction Circuit.

A frequency up-conversion piezoelectric energy harvester (FUC-PEH) consists of a force amplifier, a piezoelectric stack, a low-frequency oscillator (LFO), and a stop limiter. The force amplifier generates the amplification of stress on the piezoelectric stack. The LFO, comprising a spring and a mass block, impacts the stop limiter during vibration to induce high-frequency oscillations within the piezoelectric stack. In this paper, we represent and simplify the FUC-PEH as a lumped-parameter model based on piezoelectric material constitutive equations and structural dynamic theories. Using the electromechanical analogy, we developed an equivalent circuit model (ECM) of the FUC-PEH. A parametric study was performed to investigate the impact of system parameters, such as spring stiffness and concentrated mass, on the FUC-PEH performance. The collision-induced amplitude truncation (AT) effect enlarges the operation bandwidth. ECM simulations show that low-frequency input excitation is converted into a high-frequency output response, enhancing the energy conversion efficiency. Furthermore, we aimed to improve the FUC-PEH's performance using a synchronous electric charge extraction (SECE) circuit. Using the ECM approach, we established a system-level model that considers the electromechanical coupling behavior. The simulation results provide insights into the performance of FUC harvesters with SECE circuits and offer valuable design guidance.

Thermal Activation of Anti-Stokes Photoluminescence in CsPbBr3 Perovskite Nanocrystals: The Role of Surface Polaron States.

Optically driven cooling of a material, or optical refrigeration, is possible when optical up-conversion via anti-Stokes photoluminescence (ASPL) is achieved with near-unity quantum yield. The recent demonstration of optical cooling of CsPbBr3 perovskite nanocrystals (NCs) has provided a path forward in the development of semiconductor-based optical refrigeration strategies. However, the mechanism of ASPL in CsPbBr3 NCs is not yet settled, and the prospects for cooling technologies strongly depend on details of the mechanism. By analyzing the Arrhenius behavior of ASPL in CsPbBr3 NCs, we investigated the relationship between the average energy gained per photon during up conversion, ΔE, and the thermal activation energy, Ea. We find that Ea is systematically larger than ΔE, and that Ea increases for larger ΔE. We suggest that the additional energetic cost is due to a rearrangement of the crystal lattice as charge carriers pass from surface localized, structurally distinct sub-gap polaron states to the free exciton state during up-conversion. Our interpretation is further corroborated by quantifying the impact of ligand coverage on the NC surface. These findings help inform the development of CsPbBr3 NCs for applications in optical refrigeration.

Preliminary investigation of nitric oxide release from upconverted nanoparticles excited at 808 nm near-infrared for brain tumors.

Upconverted UCNPs@mSiO2-NH2 nanoparticles were synthesized via thermal decomposition while employing the energy resonance transfer principle and the excellent near-infrared (NIR) light conversion property of up-conversion. The 808 nm NIR-excited photocontrolled nitric oxide (NO) release platform was successfully developed by electrostatically loading photosensitive NO donor Roussin's black salt (RBS) onto UCNPs@mSiO2-NH2, enabling the temporal, spatial, and dosimetric regulation of NO release for biological applications of NO. The release of NO ranged from 0.015⁓0.099 mM under the conditions of 2.0 W NIR excitation power, 20 min of irradiation time, and UCNPs@mSiO2-NH2&RBS concentration of 0.25⁓1.25 mg/mL. Therefore, this NO release platform has an anti-tumor effect. In vitro experiments showed that under the NIR light, at concentrations of 0.3 mg/mL and 0.8 mg/mL of UCNPs@mSiO2-NH2&RBS, the activity of glioma (U87) and chordoma (U-CH1) cells, as measured by CCK8 assay, was reduced to 50 %. Cell flow cytometry and Western Blot experiments showed that NO released from UCNPs@mSiO2-NH2&RBS under NIR light induced apoptosis in brain tumor cells. In vivo experiments employing glioma and chordoma xenograft mouse models revealed significant inhibition of tumor growth in the NIR and UCNPs@mSiO2-NH2&RBS group, with no observed significant side effects in the mice. Therefore, NO released by UCNPs@mSiO2-NH2&RBS under NIR irradiation can be used as a highly effective and safe strategy for brain tumor therapy.

Upconversion nanoparticles doped optical lens: let's see the near-infrared light.

The human cannot detect light with a wavelength exceeding 700 nm, primarily due to limitations in the physiological structure of the human eye. However, in certain specific scenarios, the ability to detect near-infrared (NIR) light proves to be extremely valuable. To attain this desired capability, NIR up conversion nanoparticles (UCNPs) were prepared and doped in the optical lens materials, aiming to obtain a NIR light "visible" optical lens. It is demonstrated that the doping of UCNPs in the optical lens materials does not significantly impact on their mechanical properties, optical properties, surface properties and it exhibits excellent biocompatibility in cell and animal experiments. More importantly, the UCNPs doping can convert NIR light into visible light within the material effectively and stably. The eyes can "see" the NIR light after wearing such UCNPs doped optical lens. Such NIR light visible optical lens could have great potential in actual applications.