[The effect of erbium laser pretreatment on bond strength between dentin and enamel and microleakage at the edge of CAD/CAM glass ionomer cement restorations for repairing tooth defects].

PURPOSE: To investigate the effects of erbium laser pretreatment on the bond strength of dentin and enamel,as well as microleakage at the edge of tooth defects repaired with computer-aided design (CAD) and computer-assisted manufacturing (CAM) glass-ceramic restorations for repairing dental defects. METHODS: A total of 62 fresh, nondecayed, nondiscoloration and noncracked wisdom teeth were collected from the Oral Surgery Clinic between January 2020 and January 2023. According to different pretreatment methods, they were randomly divided into two groups, erbium laser group and phosphoric acid group, with 31 teeth in each group. Each group was further divided into two subsets for bond strength testing (16 teeth) and microleakage testing (15 teeth).The shear bond strength between enamel and dentin of both groups was compared, as well as the degree and distribution of microleakage.Statistical analysis was performed with SPSS 17.0 software package. RESULTS: The shear bond strength between enamel and dentin of the erbium laser group was significantly higher than that of the phosphoric acid group (P＜0.05); the degree and distribution of microleakage at the lateral walls and gumline of the erbium laser group were significantly lower than those of the phosphoric acid group (P＜0.05). The scores of microleakage at the lateral walls of the erbium laser group mainly concentrated in grade 1 and 2, whereas those of the phosphoric acid group mainly concentrated in grade 2. There was significant difference in the distribution of lateral wall microleakage scores between the two groups (P＜0.05). The scores of microleakage at the gumline of the erbium laser group mainly concentrated in grade 1 and 2, whereas those of the phosphoric acid group mainly concentrated in grade 2 and 3. There was significant difference in the distribution of gumline microleakage scores between the two groups (P＜0.05). CONCLUSIONS: Erbium laser pretreatment can improve bonding strength between glass ionomer cement and dentin and enamel, reduce microleakage at the edge of CAD/CAM glass ionomer cement restorations, and enhance marginal fit.

Upconverting Nanoparticle-based Enhanced Luminescence Lateral-Flow Assay for Urinary Biomarker Monitoring.

Development of efficient portable sensors for accurately detecting biomarkers is crucial for early disease diagnosis, yet remains a significant challenge. To address this need, we introduce the enhanced luminescence lateral-flow assay, which leverages highly luminescent upconverting nanoparticles (UCNPs) alongside a portable reader and a smartphone app. The sensor's efficiency and versatility were shown for kidney health monitoring as a proof of concept. We engineered Er3+- and Tm3+-doped UCNPs coated with multiple layers, including an undoped inert matrix shell, a mesoporous silica shell, and an outer layer of gold (UCNP@mSiO2@Au). These coatings synergistically enhance emission by over 40-fold and facilitate biomolecule conjugation, rendering UCNP@mSiO2@Au easy to use and suitable for a broad range of bioapplications. Employing these optimized nanoparticles in lateral-flow assays, we successfully detected two acute kidney injury-related biomarkers─kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL)─in urine samples. Using our sensor platform, KIM-1 and NGAL can be accurately detected and quantified within the range of 0.1 to 20 ng/mL, boasting impressively low limits of detection at 0.28 and 0.23 ng/mL, respectively. Validating our approach, we analyzed clinical urine samples, achieving biomarker concentrations that closely correlated with results obtained via ELISA. Importantly, our system enables biomarker quantification in less than 15 min, underscoring the performance of our novel UCNP-based approach and its potential as reliable, rapid, and user-friendly diagnostics.

Synthesis, structural, and optical behavior of erbium-doped silicophosphate glasses for photonics applications.

Erbium-incorporated silicophosphate glasses are very desirable in principal sectors such as photonics, optoelectronics, lasers, and illuminating diodes. The focus of the current investigation has been on determining how the erbium dopant affects the optical, physical, and structural characteristics of the silicophosphate-based glasses. The pure silicophosphate glasses and doped with various contents of erbium were prepared by the sol-gel process in this work. The noncrystalline character of the glasses synthesized was confirmed by the XRD patterns that were obtained. The optical measurement showed that the addition of trivalent erbium ions resulted in an increase in the refractive index of the samples and a decrease in their energy band gap values. It demonstrated the presence of P-O-P linkage stretching vibration modes that were both symmetrical and asymmetrical, P-O in PO4 bending vibration modes, OH group elongating and flexure vibrations, and P-O-H water absorption in glasses. The theoretical values of the optical basicity (Ʌth) increased from 0.465 to 0.472, while the values of the interaction parameter (A) decreased from 0.218 to 0.214 Š- 3 $$ {\overset{\ocirc }{\mathrm{A}}}^{-3} $$ . Silicophosphate glasses doped with trivalent erbium ions show promise as optoelectronic and optical filter system materials.

Rapid detection of microalgae cells based on upconversion nanoprobes.

The quantification of microalgae cells is crucial for the treatment of ships' ballast water. However, achieving rapid detection of microalgae cells remains a substantial challenge. Here, we develop a new method for rapid and effective detection of microalgae concentration by utilizing upconversion nanoprobes (UCNPs) of NaYF4:Er3+,Tm3+. Three ligands, carboxylated methoxypolyethylene glycols with 5000 and 2000 molecular weights (mPEG-COOH-5, mPEG-COOH-2) and D-gluconic acid sodium salt (DGAS), were used to convert hydrophobic UCNPs into a hydrophilic state through modification. The results show that the mPEG-COOH-5 modified UCNPs present the highest stability in an aqueous solution. Fourier Transform Infrared Spectroscopy (FTIR) measurements reveal the presence of a significant number of -COOH functional groups on UCNPs after the mPEG-COOH-5 modification. These -COOH groups enhance the hydrophilicity and biocompatibility of UCNPs. The soluble UCNPs were directly mixed with microalgae, and the upconversion luminescence (UCL) spectra of the UCNPs were recorded immediately after thorough shaking. This greatly reduces the measurement time and could realize rapid onboard detection. In this sensing procedure, the UCNPs with red UCL functioned as energy donors, while microalgae with red absorption served as an energy acceptor. The UCL gradually diminishes with an increase in microalgae concentration based on the inner filter effect, thus establishing a relationship between UCL and microalgae concentration. The accuracy of the detection is further validated through the traditional microscope counting method. These findings pave the way for a novel rapid strategy to assess microalgae concentration using UCNPs.

Luminescence properties of CdF2 single crystals co-doped with Er3+ and Y3+ ions.

The luminescence properties of erbium and yttrium co-doped cadmium difluoride with three different concentrations of yttrium were investigated. First, we synthesized single crystal samples with good optical quality using the Bridgman technique. From the optical absorption spectra, recorded at room temperature, both in the ultraviolet-visible and infrared spectral ranges, Judd-Ofelt analysis was performed based on yttrium concentrations to predict the radiative properties of Er3+ luminescent ions. For the 10% optimum concentration of yttrium, a detailed photoluminescence investigation was carried out. We mainly explored green, red, and near-infrared fluorescence under different excitation wavelengths and presented their highlight spectroscopic characteristics. The desired transitions had relatively high emission cross-sections both under visible and near-infrared excitation. Optical gain followed a similar trend. Furthermore, the dynamic fluorescence study showed a significant increase in the measured lifetime under an 800 nm infrared excitation. The upconversion process under an 800 nm excitation produced quantum efficiency greater than 100% due to the contribution of more than one energy transfer mechanism.

Te4+ and Er3+ doped ZrO2 nanoparticles with enhanced photocatalytic, antibacterial activity and dielectric properties: A next generation of multifunctional material.

Amid rising water contamination from industrial sources, tackling toxic dyes and pathogens is critical. Photocatalysis offers a cost-effective and eco-friendly solution to this pressing challenges. Herein, we synthesized Te4+ and Er3+ doped ZrO2 photocatalysts through hydrothermal method and investigated their efficacy in degrading Congo red (CR) and pathogens under visible light. XRD and Raman Spectroscopy confirm monoclinic and tetragonal mixed-phases without any impurities. Doping-induced defects, reduced crystalline diameter, high surface area, modified bandgap (2.95 eV), photoluminescence quenching, coupled with interfacial polarization, contribute to EZO's excellent dielectric response (1.149 × 106), for achieving remarkable photocatalytic activity, verified by photoelectrochemical measurements, LC-MS and phytotoxicity analysis. Under optimal conditions, EZO achieves 99% CR degradation within 100 min (TOC 79.9%), surpassing ZO (77%) and TZO (84%). Catalyst dosages, dye concentrations, and solution pH effect on EZO's photocatalytic performance are systematically assessed. Scavenging experiment emphasized the pivotal role of · OH in CR degradation with 96.4% efficiency after 4 cycles, affirming its remarkable stability. Moreover, EZO demonstrates ROS-mediated antibacterial activity against E. faecalis and E. coli bacteria under visible light, achieving >97% and >94% inhibition rate with an inhibition zone > 3 mm. Hence, the nanoparticle's dual action offers a practical solution for treating contaminated wastewater, ensuring safe irrigation.

Enhanced detection of endocrine disrupting chemicals in on-chip microfluidic biosensors using aptamer-mediated bridging flocculation and upconversion luminescence.

Exposure to endocrine-disrupting chemicals (EDCs) can lead to detrimental impacts on human health, making their detection a critical issue. A novel approach utilizing on-chip microfluidic biosensors was developed for the simultaneous detection of two EDCs, namely, bisphenol A (BPA) and diethylstilbestrol (DES), based on upconversion nanoparticles doped with thulium (Tm) and erbium (Er), respectively. From the perspective of single nanoparticles, the construction of an active core-inert shell structure enhanced the luminescence of nanoparticles by 2.28-fold (Tm) and 1.72-fold (Er). From the perspective of the nanoparticle population, the study exploited an aptamer-mediated bridging flocculation mechanism and effectively enhanced the upconversion luminescence of biosensors by 8.94-fold (Tm) and 7.10-fold (Er). A chip with 138 tangential semicircles or quarter-circles was designed and simulated to facilitate adequate mixing, reaction, magnetic separation, and detection conditions. The on-chip microfluidic biosensor demonstrated exceptional capabilities for the simultaneous detection of BPA and DES with ultrasensitive detection limits of 0.0076 µg L-1, and 0.0131 µg L-1, respectively. The first reported aptamer-mediated upconversion nanoparticle bridging flocculation provided enhanced luminescence and detection sensitivity for biosensors, as well as offering a new perspective to address the instability of nanobiosensors.

Tellurite Glasses from the 70TeO2-5XO-10P2O5-10ZnO-5PbF2(X= Pb, Bi, Ti) System Doped Erbium Ions-The Influence of Erbium on the Structure and Physical Properties.

In this article, we present research on the influence of erbium ions on the structure and magneto-optical properties of 70TeO2-5XO-10P2O5-10ZnO-5PbF2 (X = Pb, Bi, Ti) tellurite glass systems. Structural changes occurring in the glasses during doping with erbium ions were investigated using positron annihilation lifetime spectroscopy (PALS) and Raman spectroscopy. The X-ray diffraction (XRD) method was used to confirm the amorphous structure of the investigated samples. Based on the Faraday effect measurements and calculated values of Verdet constant, the magneto-optical properties of the glasses were determined.

Comparative study of upconversion and photoacoustic measurements of Er3+/Yb3+doped La2O3phosphor under 980 nm.

The Er3+/Yb3+doped La2O3phosphor samples were synthesized by the combustion method and then photoluminescence and photoacoustic spectroscopic studies were done. Prepared samples were annealed at 800 °C, 1000 °C and 1300 °C and all samples were found in pure hexagonal phase as confirmed by XRD analysis. From FE-SEM images it is found that particle size increases with increase in annealing temperature. The frequency upconversion emission spectra of samples were recorded by exciting the sample with 980 nm diode laser and maximum emission intensity is obtained for the sample annealed at 1000 °C for 2 h. A photoacoustic cell was designed and wavelength dependent photoacoustic spectra were measured. The effect of sample storage time on radiative and non-radiative emission properties of sample was checked by measuring upconversion emission and photoacoustic spectra, simultaneously. It is observed that the emission intensity and photoacoustic signal both decreases with time. The maximum photoacoustic signal is obtained around 974 nm wavelength and it indicates its potential for photo-thermal therapy using infrared excitation.

Narrow Linewidth Half-Open-Cavity Random Laser Assisted by a Three-Grating Ring Resonator for Strain Detection.

A stabilized narrow-linewidth random fiber laser for strain detection, based on a three-grating ring (TGR) resonator and half-open-cavity structure, is proposed and investigated experimentally. The half-open-cavity structure proved to provide double optical gain of erbium-doped fiber, which was beneficial to increase the photon lifetime as well as further narrow the linewidth. Meanwhile, the stability and frequency noise of narrow lasing output was improved by suppressing the competition-induced undesired residual random lasing modes with the TGR resonator. The TGR resonator is composed of a double-cavity fiber Bragg grating Fabry-Perot (FBG-FP) interferometer, a section of single-mode fiber, and a circulator. The specially designed double-cavity FBG-FP interferometer embedded in the TGR resonator acted as the strain-sensing element and improved the resolution of the dynamic strain. A stable ultra-narrow linewidth of about 205 Hz was obtained. The frequency noise was reduced to about 2 Hz/√Hz. A high dynamic strain measuring resolution of 35 femto-strain (fε)/√Hz was achieved.

Emerging green light emission of Er3+ -activated single phased GdAlO3 phosphors for lighting applications.

An erbium ion (Er3+ )-activated gadolinium aluminate (GdAlO3 ) nanophosphor was synthesized by utilizing urea assisted gel-combustion method. The crystal structure along with all other crystal parameters was determined by X-ray diffraction (XRD) patterns. The selected samples are of orthorhombic phase with Pnma space group. The agglomerated particles within nanorange have been confirmed by transmission electron microscopy (TEM) micrographs. Elemental investigation was performed by energy dispersive X-ray spectroscopy (EDX). Photoluminescence excitation (PLE) spectrum reveals a strong excitation band corresponding to the gadolinium ion (Gd3+ ) (276 nm) and a band near ultraviolet (UV) absorption for Er3+ (377 nm). Strong excitation band of Gd3+ was evident for the energy transfer between Gd3+ and Er3+ ions. All the doped sampled are excited at 377 nm wavelength. The photoluminescence (PL) spectrum exhibits an intense band at 546 nm (4 S3/2 → 4 I15/2 ) which is responsible for the green emission in the processed samples. The color coordinate values define their color in the green region and correlated color temperature (CCT) values affirm their utility as a cold light source.

Multifunctional cellulose fibers: Intense red upconversion under 1532 nm excitation and temperature-sensing properties.

The unique properties of upconverting nanoparticles are responsible for their various applications in photonic materials, medicine, analytics, or energy conversion. In this work, the NaErF4:Tm3+@NaYF4 core@shell nanoparticles were synthesized by reaction in high-boiling point solvents and incorporated into cellulose fibers. Nanoparticles showed intense upconversion under 1532 nm excitation wavelength due to Er3+ in their structure. Additional co-doping with Tm3+ ions allowed to shift of the typical green luminescence of Er3+ ions to red especially demanded in anti-counterfeiting applications. The products' composition, morphology, and structure parameters confirmed their requested properties. The article demonstrates that cellulose fibers are suitable carriers of NaErF4:Tm3+@NaYF4 NPs. We also show that the temperature-dependent emission of Er3+ ions allows for the preparation of temperature-sensing cellulose fibers.

Quantification of the Activator and Sensitizer Ion Distributions in NaYF4 :Yb3+ , Er3+ Upconverting Nanoparticles Via Depth-Profiling with Tender X-Ray Photoemission.

The spatial distribution and concentration of lanthanide activator and sensitizer dopant ions are of key importance for the luminescence color and efficiency of upconverting nanoparticles (UCNPs). Quantifying dopant ion distributions and intermixing, and correlating them with synthesis methods require suitable analytical techniques. Here, X-ray photoelectron spectroscopy depth-profiling with tender X-rays (2000-6000 eV), providing probe depths ideally matched to UCNP sizes, is used to measure the depth-dependent concentration ratios of Er3+ to Yb3+ , [Er3+ ]/[Yb3+ ], in three types of UCNPs prepared using different reagents and synthesis methods. This is combined with data simulations and inductively coupled plasma-optical emission spectroscopy (ICP-OES) measurements of the lanthanide ion concentrations to construct models of the UCNPs' dopant ion distributions. The UCNP sizes and architectures are chosen to demonstrate the potential of this approach. Core-only UCNPs synthesized with XCl3 ·6H2 O precursors (ß-phase) exhibit a homogeneous distribution of lanthanide ions, but a slightly surface-enhanced [Er3+ ]/[Yb3+ ] is observed for UCNPs prepared with trifluroacetate precursors (α-phase). Examination of Yb-core@Er-shell UCNPs reveals a co-doped, intermixed region between the single-doped core and shell. The impact of these different dopant ion distributions on the UCNP's optical properties is discussed to highlight their importance for UCNP functionality and the design of efficient UCNPs.

Facile synthesized NaGdF4 :Yb,Er peanut-shaped, highly biocompatible, colloidal upconversion nanospheres.

A facile method was used for the synthesis of peanut-shaped very emissive NaGdF4 :Yb, Er upconversion nanospheres (UCNSs) at lower temperatures with uniform size distribution. Crystallographic structure, phase purity, morphology, thermal robustness, biocompatibility, colloidal stability, surface chemistry, optical properties, and luminesce properties were explored by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), zeta potential, thermogravimetric/differential thermal analysis (TGA/DTA), Fourier-transform infrared (FTIR), ultraviolet (UV)-visible and photoluminescence spectroscopic tools. XRD pattern verified the construction of a single-phase, highly-crystalline NaGdF4 phase with a hexagonal structure. Peanut-shaped morphology of the sample was obtained from SEM micrographs which were validated from high-resolution TEM images, to have an equatorial diameter of 170 to 200 nm and a length of 220 to 230 nm, with irregular size, monodispersed, porous structure, and rough surface of the particles. The positive zeta potential value exhibited good biocompatibility along with high colloidal stability as observed from the absorption spectrum. The prepared UCNSs revealed high dispersibility, irregular size peanut-shaped morphology, rough surface, good colloidal stability, and excellent biocompatibility in aqueous media. A hexagonal phase NaGdF4 doped with ytterbium (Yb) and erbium (Er) UCNSs revealed the characteristics of highly dominant emissions located at 520-525, 538-550, and 659-668 nm corresponding to the 2 H11/2 → 4 I15/2 , 4 S3/2 → 4 I15/2 , and 4 F9/2 → 4 I15/2 transition of Er3+ ions, respectively, as a result of energy transfer from sensitizer Yb3+ ion to emitter Er3+ ion.

Integration of Au Nanosheets and GdOF:Yb,Er for NIR-I and NIR-II Light-Activated Synergistic Theranostics.

The local hyperthermia (>41 °C) effect of photothermal therapy (PTT) is significantly limited by the efficiency of PTT agents to convert laser energy to heat, and such oncotherapy, similar to conventional chemotherapy, invariably encounters the challenge of nonspecific application. Undue reliance on oxygen sources still poses particular difficulties in photodynamic therapy (PDT) for deep-level clinical applications. Considering these therapeutic issues, in this study, we constructed a versatile but unique nanosystem by encapsulating Au nanosheets in codoped gadolinium oxyfluoride (GdOF):Yb,Er spheres, followed by decoration of a chemotherapeutic drug (doxorubicin), photosensitizer (rose Bengal, RB), and targeted agent (folic acid). This allowed the incorporation of cancer treatment and real-time curative efficacy monitoring into one single theranostic nanoplatform. Benefiting from the dual contribution of the strong absorptions in the NIR-I and NIR-II regions, relevant photothermal-conversion efficiency (η) values pertaining to that final product were 39.2% at 1064 nm irradiation and 35.7% at 980 nm illumination. The fluorescence resonance energy transfer that occurred in the up-converted GdOF:Yb,Er to RB contributed to the high PDT efficacy. Combined with a micromeric acid-responsive drug release in a targeted tumor microenvironment, high-performance synergistic therapy was realized. In addition, up-conversion fluorescence imaging and computed tomography imaging accompanied by multimodal magnetic resonance imaging were simultaneously achieved owing to the doped lanthanide ions and the encapsulated Au nanosheets. Our designed oncotherapy nanosystem provides an alternative strategy to acquire ideal theranostic effects.

Photonic Crystal Effects on Upconversion Enhancement of LiErF4:0.5%Tm3+@LiYF4 for Noncontact Cholesterol Detection.

Cholesterol is a vital compound in maintenance for human health, and its concentration levels are tightly associated with various diseases. Therefore, accurate monitoring of cholesterol is of great significance in clinical diagnosis. Herein, we fabricated a noncontact biosensor based on photonic crystal-enhanced upconversion nanoparticles (UCNPs) for highly sensitive and interference-free cholesterol detection. By compounding LiErF4:0.5%Tm3+@LiYF4 UCNPs with poly(methyl methacrylate) (PMMA) photonic crystals (OPCs), we were able to selectively tune the coupling of the photonic band gap to the excitation field and modulate the upconversion (UC) luminescence intensity, given the unique multi-wavelength excitation property of LiErF4:0.5%Tm3+@LiYF4. A 48.5-fold enhancement of the monochromatic red UC emission was ultimately achieved at 980 nm excitation, ensuring improved detection sensitivity. Based on the principle of quenching of the intense monochromic red UC emission by the oxidation products of 3,3',5,5'-tetramethylbenzidine (TMB) yielded from the cholesterol cascade reactions, the biosensor has a detection limit of 1.6 µM for cholesterol with excellent specificity and stability. In addition, the testing results of the as-designed biosensor in patients are highly consistent with clinical diagnostic data, providing a sensitive, reliable, reusable, interference-free, and alternative strategy for clinical cholesterol detection.

Dual-Responsive and ROS-Augmented Nanoplatform for Chemo/Photodynamic/Chemodynamic Combination Therapy of Triple Negative Breast Cancer.

Integrating chemodynamic therapy (CDT) and photodynamic therapy (PDT) into one nanoplatform can produce much more reactive oxygen species (ROS) for tumor therapy. Nevertheless, it is still a great challenge to selectively generate sufficient ROS in tumor regions. Meanwhile, CDT and PDT are restricted by insufficient H2O2 content in the tumor as well as by the limited tumor tissue penetration of the light source. In this study, a smart pH/ROS-responsive nanoplatform, Fe2+@UCM-BBD, is rationally designed for tumor combination therapy. The acidic microenvironment can induce the pH-responsive release of doxorubicin (DOX), which can induce tumor apoptosis through DNA damage. Beyond that, DOX can promote the production of H2O2, providing sufficient materials for CDT. Of note, upconversion nanoparticles at the core can convert the 980 nm light to red and green light, which are used to activate Ce6 to produce singlet oxygen (1O2) and achieve upconversion luminescence imaging, respectively. Then, the ROS-responsive linker bis-(alkylthio)alkene is cleaved by 1O2, resulting in the release of Fenton reagent (Fe2+) to realize CDT. Taken together, Fe2+@UCM-BBD exhibits on-demand therapeutic reagent release capability, excellent biocompatibility, and remarkable tumor inhibition ability via synergistic chemo/photodynamic/chemodynamic combination therapy.

Ex vivo interaction study of NaYF4 :Yb,Er nanophosphors with isolated mitochondria.

Ex vivo interaction of NaYF4 :Yb,Er nanophosphors with isolated mitochondria has been investigated. The nanophosphors were synthesized using the hydrothermal method. The synthesized NaYF4 :Yb,Er nanophosphors were characterized for physicochemical properties. The NaYF4 :Yb,Er nanophosphors showed successful upconversion with excitation wavelength lying in the near-infrared region. The effect of synthesized NaYF4 :Yb,Er nanophosphors on mitochondria isolated from the chicken heart tissue was examined through ROS generation capacity, membrane fluidity, and complex II activity. The exposer of NaYF4 :Yb,Er nanophosphors to isolated mitochondria inhibits ROS generation activity as compared to control. The mitochondria membrane fluidity of the lipid bilayer and complex-II activity of mitochondria was observed to be unaltered after the interaction with NaYF4 :Yb,Er nanoparticles. The results confirm that synthesized NaYF4 :Yb,Er nanoparticles can be used as a safe contrast agent.

A High Separation Factor for 165Er from Ho for Targeted Radionuclide Therapy.

Background: Radionuclides emitting Auger electrons (AEs) with low (0.02-50 keV) energy, short (0.0007-40 µm) range, and high (1-10 keV/µm) linear energy transfer may have an important role in the targeted radionuclide therapy of metastatic and disseminated disease. Erbium-165 is a pure AE-emitting radionuclide that is chemically matched to clinical therapeutic radionuclide 177Lu, making it a useful tool for fundamental studies on the biological effects of AEs. This work develops new biomedical cyclotron irradiation and radiochemical isolation methods to produce 165Er suitable for targeted radionuclide therapeutic studies and characterizes a new such agent targeting prostate-specific membrane antigen. Methods: Biomedical cyclotrons proton-irradiated spot-welded Ho(m) targets to produce 165Er, which was isolated via cation exchange chromatography (AG 50W-X8, 200-400 mesh, 20 mL) using alpha-hydroxyisobutyrate (70 mM, pH 4.7) followed by LN2 (20-50 µm, 1.3 mL) and bDGA (50-100 µm, 0.2 mL) extraction chromatography. The purified 165Er was radiolabeled with standard radiometal chelators and used to produce and characterize a new AE-emitting radiopharmaceutical, [165Er]PSMA-617. Results: Irradiation of 80-180 mg natHo targets with 40 µA of 11-12.5 MeV protons produced 165Er at 20-30 MBq·µA-1·h-1. The 4.9 ± 0.7 h radiochemical isolation yielded 165Er in 0.01 M HCl (400 µL) with decay-corrected (DC) yield of 64 ± 2% and a Ho/165Er separation factor of (2.8 ± 1.1) · 105. Radiolabeling experiments synthesized [165Er]PSMA-617 at DC molar activities of 37-130 GBq·µmol-1. Conclusions: A 2 h biomedical cyclotron irradiation and 5 h radiochemical separation produced GBq-scale 165Er suitable for producing radiopharmaceuticals at molar activities satisfactory for investigations of targeted radionuclide therapeutics. This will enable fundamental radiation biology experiments of pure AE-emitting therapeutic radiopharmaceuticals such as [165Er]PSMA-617, which will be used to understand the impact of AEs in PSMA-targeted radionuclide therapy of prostate cancer.

Contrast agents for x-ray luminescence computed tomography.

Imaging probes are an important consideration for any type of contrast agent-based imaging method. X-ray luminescence imaging (XLI) and x-ray luminescence computed tomography (XLCT) are both contrast agent-based imaging methods that employ x-ray excitable scintillating imaging probes that emit light to be measured for optical imaging. In this work, we compared the performance of several select imaging probes, both commercial and self-synthesized, for application in XLI/XLCT imaging. Commercially available cadmium telluride quantum dots (CdTe QDs) and europium-doped gadolinium oxysulfide (GOS:Eu) microphosphor as well as synthesized NaGdF4 nanophosphors doped with either europium or terbium were compared through their x-ray luminescence emission spectra, luminescence intensity, and also by performing XLCT scans using phantoms embedded with each of the imaging probes. Each imaging probe displayed a unique emission spectrum that was ideal for deep-tissue optical imaging. In terms of luminescence intensity, due to the large particle size, GOS:Eu had the brightest emission, followed by NaGdF4:Tb, NaGdF4:Eu, and finally the CdTe QDs. Lastly, XLCT scans showed that each imaging probe could be reconstructed with good shape and location accuracy.