Cs₂NaGdCl₆:Tb³⁺A Highly Luminescent Rare-Earth Double Perovskite Scintillator for Low-Dose X‑ray Detection and Imaging

Rare-earth-based double perovskite (DP) X-ray scintillators have gained significant importance with low detection limits in medical imaging and radiation detection owing to their high light yield (LY) and remarkable spatial resolution. Herein, we report the synthesis of 3D double perovskite (DP) crystals, namely, Cs2NaGdCl6 and Tb3+-Cs2NaGdCl6 using hydrothermal reaction. Cs2NaGdCl6 DP single crystals exhibited a blue self-trapped exciton (STE) emission at 470 nm under ultraviolet (265 nm) excitation with a photoluminescence quantum yield (PLQY) of 8.4%. Introducing Tb3+ ions into Cs2NaGdCl6 has resulted in quenching of STE emission and enhancing green emission at 549 nm attributed to the 5D4 → 7F5 transition of Tb3+, suggesting efficient energy transfer (ET) from STE to Tb3+. This ET process is evidenced by the appearance of Tb3+ bands in the excitation spectra of the host, the shortening of the STE lifetimes in the presence of Tb3+ ions, and the enhancement of PLQY (72.6%). Furthermore, Cs2NaGdCl6:5%Tb3+ films of various thicknesses (0.1–0.6 mm) were synthesized and their X-ray scintillating performance has been examined. The Cs2NaGdCl6:5%Tb3+ film with 0.4 mm thickness has exhibited an excellent linear response to the X-ray dose rate with a low detection limit of 41.32 nGyair s–1, an LY of 39,100 photons MeV–1, and excellent radiation stability. Benefiting from the strong X-ray excited luminescence (XEL) of Cs2NaGdCl6:5%Tb3+, we developed a Cs2NaGdCl6:5%Tb3+ X-ray scintillator screen with a least thickness (0.1 mm), exhibiting remarkable imaging ability with a spatial resolution of 10.75 lp mm–1. These results suggest that Cs2NaGdCl6:Tb3+ can be a potential candidate for low-dose and X-ray imaging applications

The identification of the intracellular distribution of FIONs in macrophages.

<p>(A) Microscopic view (400×) of macrophages treated with FIONs (50 µg Fe/mL). The ingested FIONs were visualized by Prussian blue staining (left: phase, right: Prussian blue). (B) The location of the FIONs was further confirmed by electron microscopy (left: 15000×, right: 30000×), which revealed that the ingested FIONs were located in cytoplasmic organelles (arrows).</p

The physiological functions of macrophages after FIONs labeling.

<p>(A) Cell viability test of the macrophages after exposure to varying concentrations of the FIONs for 2 h. The cell viability at the concentration of 100 µg Fe/mL FION concentration was significantly lower than the other concentrations tested (* <i>P</i><0.001). (B) No significant differences in the cell viability were observed after treatment with FIONs (50 µg Fe/mL) for varying times (<i>P</i> = 0.5393). (C) The efficiency of phagocytosis decreased as the incubation time of the macrophages with the FIONs increased. Macrophages were incubated with FIONs (50 µg Fe/mL) at 37°C for the indicated times, and the efficiency of phagocytosis was determined. The incubation times of 6 and 12 h showed significant differences when compared to the untreated group (* <i>P</i>>0.05, ** <i>P</i><0.05, *** <i>P</i><0.01). (D) Macrophages were incubated with FIONs (50 µg Fe/mL) at 37°C for the indicated times, and then a macrophage migration assay was performed. No statistically significant differences were evident between the untreated and the FION treated groups (50 µg Fe/mL). All experiments were analyzed using the ANOVA test and the Tukey-Kramer multiple comparison test.</p

Water-Dispersible Ferrimagnetic Iron Oxide Nanocubes with Extremely High <i>r</i>₂ Relaxivity for Highly Sensitive in Vivo MRI of Tumors

The theoretically predicted maximum <i>r</i>₂ relaxivity of iron oxide nanoparticles was achieved by optimizing the overall size of ferrimagnetic iron oxide nanocubes. Uniform-sized iron oxide nanocubes with an edge length of 22 nm, encapsulated with PEG-phospholipids (WFION), exhibited high colloidal stability in aqueous media. In addition, WFIONs are biocompatible and did not affect cell viability at concentrations up to 0.75 mg Fe/ml. Owing to the enhanced colloidal stability and the high <i>r</i>₂ relaxivity (761 mM^–1 s^–1), it was possible to successfully perform in vivo MR imaging of tumors by intravenous injection of 22-nm-sized WFIONs, using a clinical 3-T MR scanner

Identification of macrophages in the intraperitoneal cells by FACS.

<p>Over 95% of the intraperitoneal cells were F4/80 positive (Black: no staining, Green: F4/80 staining).</p

Sagittal T2* GRE MR images of the melanoma tumor model.

<p>(A) Sagittal T2* GRE MR images were taken before and 24 h after the intravenous administration of a FION solution or the FION-labeled macrophages. The hypointensities from the FION-labeled macrophages were detected within the tumor on the day after injection. Thus, the hypointensity means the FIONs-labeled macrophages had been recruited within the tumors. Histograms show the primary tumor pixel distributions and those pixels decreasing below the threshold value (Red). Notably, very few pixels in the tumor after the intravenous injection of the FION solution fell below the threshold. (B) The percentages of hypointense pixels within the tumors of the mice treated with the FION-labeled macrophages and the FION solution alone were 12.093±4.139 (%) and 2.074±1.461 (%), respectively (* <i>P</i> = 0.0268). (C) Prussian blue staining of the main tumors revealed intracellular FIONs within the macrophages (Blue).</p

Continuous O₂‑Evolving MnFe₂O₄ Nanoparticle-Anchored Mesoporous Silica Nanoparticles for Efficient Photodynamic Therapy in Hypoxic Cancer

Therapeutic effects of photodynamic therapy (PDT) are limited by cancer hypoxia because the PDT process is dependent on O₂ concentration. Herein, we design biocompatible manganese ferrite nanoparticle-anchored mesoporous silica nanoparticles (MFMSNs) to overcome hypoxia, consequently enhancing the therapeutic efficiency of PDT. By exploiting the continuous O₂-evolving property of MnFe₂O₄ nanoparticles through the Fenton reaction, MFMSNs relieve hypoxic condition using a small amount of nanoparticles and improve therapeutic outcomes of PDT for tumors <i>in vivo</i>. In addition, MFMSNs exhibit T₂ contrast effect in magnetic resonance imaging (MRI), allowing <i>in vivo</i> tracking of MFMSNs. These findings demonstrate great potential of MFMSNs for theranostic agents in cancer therapy

Chitosan Oligosaccharide-Stabilized Ferrimagnetic Iron Oxide Nanocubes for Magnetically Modulated Cancer Hyperthermia

Magnetic nanoparticles have gained significant attention as a therapeutic agent for cancer treatment. Herein, we developed chitosan oligosaccharide-stabilized ferrimagnetic iron oxide nanocubes (Chito-FIONs) as an effective heat nanomediator for cancer hyperthermia. Dynamic light scattering and transmission electron microscopic analyses revealed that Chito-FIONs were composed of multiple 30-nm-sized FIONs encapsulated by a chitosan polymer shell. Multiple FIONs in an interior increased the total magnetic moments, which leads to localized accumulation under an applied magnetic field. Chito-FIONs also exhibited superior magnetic heating ability with a high specific loss power value (2614 W/g) compared with commercial superparamagnetic Feridex nanoparticles (83 W/g). The magnetically guided Chito-FIONs successfully eradicated target cancer cells through caspase-mediated apoptosis. Furthermore, Chito-FIONs showed excellent antitumor efficacy on an animal tumor model without any severe toxicity

Self-Assembled Fe₃O₄ Nanoparticle Clusters as High-Performance Anodes for Lithium Ion Batteries via Geometric Confinement

Although different kinds of metal oxide nanoparticles continue to be proposed as anode materials for lithium ion batteries (LIBs), their cycle life and power density are still not suitable for commercial applications. Metal oxide nanoparticles have a large storage capacity, but they suffer from the excessive generation of solid–electrolyte interphase (SEI) on the surface, low electrical conductivity, and mechanical degradation and pulverization resulted from severe volume expansion during cycling. Herein we present the preparation of mesoporous iron oxide nanoparticle clusters (MIONCs) by a bottom-up self-assembly approach and demonstrate that they exhibit excellent cyclic stability and rate capability derived from their three-dimensional mesoporous nanostructure. By controlling the geometric configuration, we can achieve stable interfaces between the electrolyte and active materials, resulting in SEI formation confined on the outer surface of the MIONCs

Multifunctional Fe₃O₄/TaO_<i>x</i> Core/Shell Nanoparticles for Simultaneous Magnetic Resonance Imaging and X-ray Computed Tomography

Multimodal imaging is highly desirable for accurate diagnosis because it can provide complementary information from each imaging modality. In this study, a sol–gel reaction of tantalum­(V) ethoxide in a microemulsion containing Fe₃O₄ nanoparticles (NPs) was used to synthesize multifunctional Fe₃O₄/TaO_<i>x</i> core/shell NPs, which were biocompatible and exhibited a prolonged circulation time. When the NPs were intravenously injected, the tumor-associated vessel was observed using computed tomography (CT), and magnetic resonance imaging (MRI) revealed the high and low vascular regions of the tumor