Y2O3:Yb3+, Tm3+/ZnO composite with a heterojunction structure and upconversion function for the photocatalytic degradation of organic dyes

Visible-near-Infrared Light-Driven Photocatalytic Characteristics of Er3+/Yb3+-Codoped BiOBr Upconverting Microparticles for Tetracycline Degradation

To settle the unsatisfying efficiency and insufficient light harvesting ability of photocatalysts, we report on the development of Er³⁺/Yb³⁺-codoped BiOBr (BiOBr:Er³⁺/xYb³⁺) microparticles that were synthesized by a rational high-temperature solid-state reaction method. The prepared microcrystals exhibit high visible upconversion (UC) emissions with maximum intensities at x = 0.01 when excited by a 980 nm laser. Remarkably, the corresponding UC emission process is attributed to a two-photon absorption route. Furthermore, the photocatalytic activities of as-synthesized compounds were further evaluated through analyzing the visible-near-infrared light-triggered tetracycline degradation. Compared with BiOBr:Er³⁺ microparticles, BiOBr:Er³⁺/xYb³⁺ microparticles present superior photocatalytic properties and the optimal status is achieved when x = 0.05, in which h⁺, ·O₂^-, and ·OH active species contribute to the photocatalytic mechanism. Additionally, the designed microparticles exhibit better photocatalytic abilities than previously reported photocatalysts (i.e., TiO₂, SnO₂) upon full-spectrum light irradiation. These results reveal that Yb³⁺ codoping is able to not only enhance the UC emission properties of BiOBr:Er³⁺ microparticles but also reinforce their photocatalytic activities. Our findings may put forward a facile strategy to regulate the photodegradation capacity of photcatalysts.

Tunable Emission and Color Temperature of Yb3+/Er3+/Tm3+-Tridoped Y2O3-ZnO Ceramic Nano-Phosphors Using Er3+ Concentration and Excitation Pump Power

In this study, a series of well-crystallized Yb³⁺/Er³⁺/Tm³⁺-tridoped Y₂O₃-ZnO ceramic nano-phosphors were prepared using sol–gel synthesis, and the phosphor structures were studied using X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The phosphors were well crystallized and exhibited a sharp-edged angular crystal structure and mesoporous structure consisting of 270 nm nano-particles. All phosphors generated blue, green, and red emission bands attributed to Tm: ¹G₄→³H₆, Er: ²H_11/2 (⁴S_3/2)→⁴I_15/2, and Er: ⁴F_9/2→⁴I_15/2 radiative transitions, respectively. Increasing in luminescent centers, weakening of lattice symmetry, and releasing of dormant rare earth ions can enhance all emissions. Er³⁺ can obtain energy from Tm³⁺ to enhance green and red emission. These colors can be tuned by optimizing the doping concentrations of the Er³⁺ ion. The color coordinates were adjusted by tuning both the Er³⁺ concentration and excitation laser pump power to shift the color coordinates and correlated color temperature. The findings of this study will broaden the potential practical applications of phosphors.

Observation of Stark splitting in micro upconversion photoluminescence spectra of polycrystalline Ln3+ doped Y2O3microspheres

In this study, Yb³⁺-Er³⁺-Tm³⁺doped Y₂O₃microspheres were synthesized using the solvothermal method. Structural, morphological, and elemental analysis was done using XRD, FESEM, and EDX characterization techniques. The optical properties of the samples were determined using UV-Vis-NIR spectroscopy and upconversion photoluminescence measurements. The anti-Stokes emission peaks from these polycrystalline phosphor microspheres were obtained using a commercial micro-photoluminescence setup equipped with a 976 nm laser as an excitation source at room temperature. It was compared with the emission spectra taken from a 2-3 mm spot size of 976 nm laser irradiation on the same sample. The micro-emission spectra were analyzed based on possible Stark splitting energy level transitions between the^2S+1L_Jmanifolds of Er³⁺and Tm³⁺ions. A detailed mechanism is outlined for emission in the entire visible region under 976 nm laser excitation.

Photodynamic Therapy of Up-Conversion Nanomaterial Doped with Gold Nanoparticles

Two key concerns exist in contemporary cancer chemotherapy: limited therapeutic efficiency and substantial side effects in patients. In recent years, researchers have been investigating the revolutionary cancer treatment techniques of photodynamic therapy (PDT) and photothermal therapy (PTT) proposed by many scholars. A photothermal treatment of cancer was synthesized using the hydrothermal method which has high photothermal conversion efficiency and can generate reactive oxygen species (ROS) in cells. Photothermal treatment of tumors has a good short-term effect and photodynamic therapy lasts longer. However, both PTT and PDT have their inevitable shortcomings and it is difficult to completely eradicate a tumor using a single mode of treatment. PTT and PDT synergistic treatment not only inherits the advantages of low toxicity and side effects of phototherapy but also enables the two treatment methods to complement each other. It is an effective strategy to improve curative effects and reduce toxic and side effects. Furthermore, gold doped UCNPs have an exceptionally high target recognition for tumor cells. The gold doped UCNPs, in particular, are non-toxic to normal tissues, endowing the as-prepared medications with outstanding therapeutic efficacy and exceptionally low side effects. These findings may encourage the creation of fresh, effective imaging-guided approaches to meet the goal of photothermal cancer therapy.

Synthesis of Rare-Earth Nanomaterials Ag-Doped NaYF4:Yb3+/Er3+@NaYF4:Nd3+@NaGdF4 for In Vivo Imaging

In this study. a novel near-infrared fluorescent-driven contrast agent (Ag-doped NaYF₄:Yb³⁺/Er³⁺@NaYF₄:Nd³⁺@NaGdF₄) was synthesized using a coprecipitation-hydrothermal-solvothermal-solvothermal (CHSS) method. The results shows that hexagonal NaYF₄:Yb³⁺/Er³⁺ with a diameter of 300 nm was successfully synthesized by the CHSS method. The new contrast agent was characterized using scanning electron microscopy, fluorescence spectrometry, transmission electron microscopy, energy-dispersive spectrometry and ultraviolet-visible light diffuse reflectance absorption spectroscopy. Even at low concentrations (0.2 M), this proposed contrast agent can be excited by near-infrared light with a wavelength of 980 nm and emits a dazzling green light with a wavelength of 540 nm, and the comparison of the luminescence intensity proves that doping with silver increases the luminescence intensity of the upconverted nanomaterial by nearly 13 times based on the calculated quantum yield. TEM images show the successful preparation of silver nanoparticles with a diameter of 30 nm, and the energy spectrum shows the successful doping of silver nanoparticles and the successful preparation of the core-shell structure of NaYF₄:Yb³⁺/Er³⁺@NaYF₄:Nd³⁺@NaGdF₄. Furthermore, the mechanism of the increased luminous intensity has been studied using simulation calculations. Finally, cytotoxicity tests were used to test material which was modified by 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG_2K), and the biocompatibility was significantly improved, meeting the standard for biological applications.

Photothermal Effect and Multi-Modality Imaging of Up-Conversion Nanomaterial Doped with Gold Nanoparticles

Two key concerns exist in contemporary cancer chemotherapy in clinics: limited therapeutic efficiency and substantial side effects in patients. In recent years, researchers have been investigating revolutionary cancer treatment techniques and photo-thermal therapy (PTT) has been proposed by many scholars. A drug for photothermal cancer treatment was synthesized using the hydrothermal method, which has a high light-to-heat conversion efficiency. It may also be utilized as a clear multi-modality bioimaging platform for photoacoustic imaging (PAI), computed tomography (CT), and magnetic resonance imaging (MRI). When compared to single-modality imaging, multi-modality imaging delivers far more thorough and precise details for cancer diagnosis. Furthermore, gold-doped upconverting nanoparticles (UCNPs) have an exceptionally high target recognition for tumor cells. The gold-doped UCNPs, in particular, are non-toxic to normal tissues, endowing the as-prepared medications with outstanding therapeutic efficacy but exceptionally low side effects. These findings may encourage the creation of fresh effective imaging-guided approaches to meet the goal of photothermal cancer therapy.

Photodynamic Therapy and Multi-Modality Imaging of Up-Conversion Nanomaterial Doped with AuNPs

Two key concerns exist in contemporary cancer chemotherapy in clinic: limited therapeutic efficiency and substantial side effects in patients. In recent years, researchers have been investigating a revolutionary cancer treatment technique, and photodynamic therapy (PDT) has been proposed by many scholars. A drug for photodynamic cancer treatment was synthesized using the hydrothermal method, which has a high efficiency to release reactive oxygen species (ROS). It may also be utilized as a clear multi-modality bioimaging platform for photoacoustic imaging (PAI) due to its photothermal effect, computed tomography (CT), and magnetic resonance imaging (MRI). When compared to single-modality imaging, multi-modality imaging delivers far more thorough and precise details for cancer diagnosis. Furthermore, Au-doped up-conversion nanoparticles (UCNPs) have an exceptionally high luminous intensity. The Au-doped UCNPs, in particular, are non-toxic to tissues without laser at an 808 nm wavelength, endowing the as-prepared medications with outstanding therapeutic efficacy but exceptionally low side effects. These findings may encourage fresh effective imaging-guided approaches to meet the goal of photodynamic cancer therapy to be created.

SiO2 Coated Up-Conversion Nanomaterial Doped with Ag Nanoparticles for Micro-CT Imaging

In this study, a new method for synthesizing Ag-NaYF4:Yb3+/Er3+ @ SiO2 nanocomposites was introduced. Using a hydrothermal method, the synthesized Yb3+- and Er3+-codoped NaYF4 up-conversion luminescent materials and Ag nanoparticles were doped into up-conversion nanomaterials and coated with SiO2 up-conversion nanomaterials. This material is known as Ag-UCNPs@SiO2, it improves both the luminous intensity because of the doped Ag nanoparticles and has low cytotoxicity because of the SiO2 coating. The morphology of UCNPs was observed using scanning electron microscopy (SEM), and the mapping confirmed the successful doping of Ag nanoparticles. Successful coating of SiO2 was confirmed using transmission electron microscopy (TEM). Fluorescence spectra were used to compare changes in luminescence intensity before and after doping Ag nanoparticles. The reason for the increase in luminescence intensity after doping with Ag nanoparticles was simulated using first-principles calculations. The cytotoxicity of Ag-UCNPs@SiO2 was tested via the cell counting kit-8 (CCK-8) method, and its imaging ability was characterized using the micro-CT method.