Structure and luminescence properties of eu3+-doped cubic mesoporous silica thin films

Europium (III) complex-based fluorescent probe for instantaneous, selective, and sensitive detection of phosgene

Phosgene (carbonyl chloride, COCl₂) is a widely used colorless gas in organic synthesis. However, its high toxicity sets a severe potential damage of public safety. As the fluorescence method has the advantages of simple operation and real-time detection of phosgene, it is extremely important to develop a fluorescent phosgene probe for public health and safety. This study aimed to present a simple Eu³⁺ complex (1) with 2-hydroxyl-1H-benzimidazole moiety as a novel phosgene probe. Probe 1 exhibited characteristic emission of Eu³⁺ in CH₃CN solution, which was specifically quenched after encountering phosgene. The change in the solution color from light red to dark could be easily distinguished with the naked eye under a 365 nm ultraviolet lamp. Finally, the test paper with probe 1 was fabricated for effortless, selective, and visual detection of phosgene gas.

Multi-functional silica-based mesoporous materials for simultaneous delivery of biologically active ions and therapeutic biomolecules

Mesoporous silica-based materials, especially mesoporous bioactive glasses (MBGs), are being highly considered for biomedical applications, including drug delivery and tissue engineering, not only because of their bioactivity and biocompatibility but also due to their tunable composition and potential use as drug delivery carriers owing to their controllable nanoporous structure. Numerous researches have reported that MBGs can be doped with various therapeutic ions (strontium, copper, magnesium, zinc, lithium, silver, etc.) and loaded with specific biomolecules (e.g., therapeutic drugs, antibiotics, growth factors) achieving controllable loading and release kinetics. Therefore, co-delivery of ions and biomolecules using a single MBG carrier is highly interesting as this approach provides synergistic effects toward improved therapeutic outcomes in comparison to the strategy of sole drug or ion delivery. In this review, we discuss the state-of-the-art in the field of mesoporous silica-based materials used for co-delivery of ions and therapeutic drugs with osteogenesis/cementogenesis, angiogenesis, antibacterial and anticancer properties. The analysis of the literature reveals that specially designed mesoporous nanocarriers can release multiple ions and drugs at therapeutically safe and relevant levels, achieving the desired biological effects (in vivo, in vitro) for specific biomedical applications. It is expected that this review on the ion/drug co-delivery concept using MBG carriers will shed light on the advantages of such co-delivery systems for clinical use. Areas for future research directions are identified and discussed. STATEMENT OF SIGNIFICANCE: Many studies in literature focus on the potential of single drug or ion delivery by mesoporous silica-based materials, exploiting the bioactivity, biocompatibility, tunable composition and controllable nanoporosity of these materials. Recenlty, studies have adopted the "dual-delivery" concept, by designing multi-functional mesoporous silica-based systems which are capable to deliver both biologically active ions and biomolecules (growth factors, drugs) simultaneously in order to achieve synergy of their complementary therapeutic activities. This review summarizes the state of the art in the field, with focus on osteogenesis/cementogenesis, angiogenesis, antibacterial and anticancer properties, and discusses the challenges and prospects for further progress in this area, expecting to generate broader interest in the technology for applications in disease treatment and regenerative medicine.

Ligand-free gold nanoclusters confined in mesoporous silica nanoparticles for styrene epoxidation

We present a novel approach to produce gold nanoclusters (Au NCs) in the pores of mesoporous silica nanoparticles (MSNs) by sequential and controlled addition of metal ions and reducing agents. This impregnation technique was followed to confine Au NCs inside the pores of MSNs without adding external ligands or stabilizing agents. TEM images show a uniform distribution of monodisperse NCs with an average size of 1.37 ± 0.4 nm. Since the NCs are grown in situ in MSN pores, additional support and high temperature calcination are not required to use them as catalysts. The use of Au NC/MSNs as a catalyst for the epoxidation of styrene in the presence of tert-butyl hydroperoxide (TBHP) as a terminal oxidant resulted in an 88% conversion of styrene in 12 h with a 74% selectivity towards styrene epoxide. Our observations suggest that this remarkable catalytic performance is due to the small size of Au NCs and the strong interaction between gold and the MSNs. This catalytic conversion is environmentally friendly as it is solvent free. We believe our synthetic approach can be extended to other metal NCs offering a wide range of applications.

N-Doped Carbon Quantum Dot (NCQD)-Deposited Carbon Capsules for Synergistic Fluorescence Imaging and Photothermal Therapy of Oral Cancer

Use of nanomaterials blessed with both therapeutic and diagnostic properties is a proficient strategy in the treatment of cancer in its early stage. In this context, our paper reports the synthesis of uniform size N-rich mesoporous carbon nanospheres of size 65-70 nm from pyrrole and aniline precursors using Triton-X as a structure-directing agent. Transmission electron microscopy reveals that these carbons spheres contain void spaces in which ultrasmall nitrogen-doped quantum dots (NCQD) are captured within the matrix. These mesoporous hollow NCQD captured carbon spheres (NCQD-HCS) show fluorescence quantum yield up to 14.6% under λ_ex = 340 nm. Interestingly, samples calcined at >800 °C clearly absorb in the wavelength range 700-1000 nm and shows light-to-heat conversion efficiency up to 52%. In vitro experiments in human oral cancer cells (FaDu) show that NCQD-HCS are internalized by the cells and induce a substantial thermal ablation effect in FaDu cells when exposed under a 980 nm near-infrared laser.

Zinc Oxide Nanoparticles-Immobilized Mesoporous Hollow Silica Spheres for Photodegradation of Sodium Dodecylbenzenesulfonate

ZnO-Immobilized mesoporous hollow silica spheres (ZnO/xMHSS; x = 15, 30, 50 molar ratio of Zn/Si) were synthesized and examined as photocatalysts toward the degradation of sodium dodecylbenzenesulfonate (SDBS). The hollow structures of MHSS and ZnO-immobilized MHSS composite were evidenced by transmission electron microscopy analysis. X-ray diffraction results confirmed the presence of ZnO and a mesoporous structure in the synthesized materials. N2 adsorption–desorption analysis also depicted the formation of a mesoporous structure and the increased surface area for the ZnO/xMHSS materials. Fourier transform infrared spectroscopy analysis revealed the formation of Si–O–Zn bonds due to interaction between ZnO and MHSS. The photocatalytic testing results indicated that all the ZnO/xMHSS materials showed improved efficiencies of 10–21 % toward the photodegradation of SDBS when compared with bare ZnO. Among the prepared materials, ZnO/15MHSS was the best photocatalyst, which photodegraded 68 % SDBS after 1 h reaction. The kinetic study demonstrated that the photocatalytic reaction followed the second-order model.

Luminescent Mesoporous Silica Built through Self-Assembly of Polyhedral Oligomeric Silsesquioxane and Europium(III) Ions

The chemical combination of completely condensed polyhedral oligomeric silsequioxanes and Eu³⁺ ions has allowed the preparation of a novel robust mesoporous silica (Eu-MesoPOSS) with interesting luminescent properties and good hydrothermal and photobleaching stability. These properties make Eu-MesoPOSS a potential candidate for the fabrication of stable and efficient luminescent devices, and a multifunctional platform for bio-imaging applications.

Photoluminescence properties of Eu(3+)-doped glaserite-type orthovanadates CsK(2)Gd[VO(4)](2)

Undoped and Eu(3+)-doped glaserite-type orthovanadates CsK2Gd1-xEux[VO4]2 with various Eu(3+) concentrations of x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 were synthesized via the solid-state reaction. The formation of a single phase compound was verified through the X-ray diffraction studies. The photoluminescence (PL) and PL excitation (PLE) spectra, PL decay curves, and absolute quantum efficiency (QE) were investigated. Unlike the conventional Eu(3+)-doped vanadates, these Eu(3+)-doped samples showed not only several sharp emission lines due to Eu(3+) but also a broad emission band with a maximum at 530 nm due to the [VO4](3-) host. The intensities of the host and Eu(3+) emissions increased when the Eu(3+) concentration was increased from x = 0 to x = 0.6 and decreased above x = 0.6. Similar concentration dependence was observed for QE. The host emission, even if in the Eu(3+)-condensed host of CsK2Eu(VO4), was never quenched indicating inefficient energy transfer from the host [VO4](3-) to Eu(3+). This inefficient energy transfer is understood by suppression of the energy transfer by the V-O-Eu bond angle deviated from 180° and the separation of Eu(3+) ions at the Gd(3+) site from [VO4](3-). Like the 530 nm charge transfer [VO4](3-) emission, two broad and intense PLE bands with maxima at 330 and 312 nm were observed for the Eu(3+) emission. A maximum QE of 38.5% was obtained from CsK2Gd1-xEux[VO4]2 (x = 0.6). A white-colored emission was obtained by the combination of the broad 530 nm emission band and the intense sharp lines due to Eu(3+) at 590-620 nm.

Novel sol-gel precursors for thin mesoporous eu(3+)-doped silica coatings as efficient luminescent materials

Europium(III) ions containing mesoporous silica coatings have been prepared via a solvent evaporation-induced self-assembly (EISA) approach of different single-source precursors (SSPs) in the presence of Pluronic P123 as a structure-directing agent, using the spin-coating process. A deliberate tailoring of the chemical composition of the porous coatings with various Si:Eu ratios was achieved by processing mixtures of tetraethylorthosilicate (TEOS) and Eu(3+)-coordinated SSPs. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) analyses demonstrate that the thin metal oxide-doped silica coatings consist of a porous network with a short-range order of the pore structure, even at high europium(III) loadings. Furthermore, luminescence properties were investigated at different temperatures and different degrees of Eu(3+) contents. The photoluminescence spectra clearly show characteristic emission peaks corresponding to the (5)D0 → (7)FJ (J = 0-5) transitions resulting in a red luminescence visible by the eyes, although the films have a very low thickness (150-200 nm).