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OBJECTIVES The current tooth bleaching materials are associated with adverse effect. Photodynamic method based on a novel photosensitizer alone, without combining with peroxides, is evaluated for tooth bleaching application. MATERIALS AND METHODS Teeth samples were randomly divided into 3 groups with different treatment schemes, including negative control group (group A, physiological saline), experimental group (group B, ZnPc(Lys)5), and the positive control group (group C, hydrogen peroxide). Tooth color, surface microhardness, and roughness were determined at baseline, right after the first and second phase of bleaching, as well as 1 week and 1 month post-bleaching. Four samples in each group was randomly selected to evaluate the changes in surface morphology using the scanning electron microscope. RESULTS The color change values (ΔE) in group B (7.10 ± 1.03) and C (12.22 ± 2.35) were significantly higher than that in group A (0.93 ± 0.30, P

Developing suitable catalysts capable of receiving injected electrons and possessing active sites for hydrogen evolution reaction (HER) is the key to building an efficient dye-sensitized system for hydrogen production. Fe3S4 is generally regarded as an inferior HER catalyst among the metal sulfide family, mainly due to its weak surface adsorption toward H atoms. In this work, we demonstrate a facile metal-organic framework-derived method to synthesize uniform Fe3S4 nanorods and active them for HER by Ni doping. Our experimental results and theoretical calculations reveal that Ni doping can greatly modify the electronic structure of Fe3S4 nanorods, improving their electron conductivity and optimizing their surface adsorption energy toward H atoms. Sensitized by a commercial organic dye (eosin-Y), 1%Ni-doped Fe3S4 nanorods display a high H2 production rate of 3240 μmol gcat-1 h-1 with an apparent quantum yield of 12% under 500 nm wavelength, which is significantly higher than that of pristine Fe3S4 and even higher than that of 1% Pt-deposited Fe3S4. The working mechanism of this dye-sensitized system is explored, and the effect of Ni-doping concentration has been studied. This work presents a facile strategy to synthesize metal-doped sulfide nanocatalysts with greatly enhanced activity toward photocatalytic H2 production.

Photocatalytic reduction of CO2 into value-added chemical fuels is an appealing approach to address energy crisis and global warming. CsPbBr3 quantum dots (QDs) are good candidates for CO2 reduction because of their excellent photoelectric properties, including high molar extinction coefficient, low exciton binding energy, and defect tolerance. However, the pristine CsPbBr3 QDs generally have low photocatalytic performance mainly due to dominant charge recombination and lack of efficient catalytic sites for CO2 adsorption/activation. Herein, we report a new photocatalytic system, in which CsPbBr3 QDs are coupled with covalent triazine frameworks (CTFs) for visible-light-driven CO2 reduction. In this hybrid photocatalytic system, the robust triazine rings and periodical pore structures of CTFs promote the charge separation in CsPbBr3 and endow them with strong CO2 adsorption/activation capacity. The resulting photocatalytic system exhibits excellent photocatalytic activity towards CO2 reduction. This work presents a new photocatalytic system based on CTFs and perovskite QDs for visible-light-driven CO2 reduction, which highlights the potential of perovskite-based photocatalysts for solar fuel applications.

Using ion doping to engineer sulfur vacancies over metal sulfides is an effective method to improve photocatalytic properties, such vacancies form the center of the electron-captured state to promote the separation and transfer of photogenerated carriers. In this research, Yb/Er co-doped bulk Cd0.5Zn0.5S (CZS) was fabricated by a one-step simple hydrothermal process, and used for evaluating the catalytic activity for aquatic hydrogen production under visible light irradiation. The results showed that the Cd0.5Zn0.5S:Yb(15%), Er obtained exhibited a higher efficient photocatalytic activity of hydrogen evolution, in which the efficiency of Cd0.5Zn0.5S:Yb(15%), Er (422.0 μmol g−1 h−1) was 2.7 times higher than that of bare Cd0.5Zn0.5S (154.7 μmol g−1 h−1). This can be attributed to the augmented active surface area, the broadened spectral absorption of visible light and the facilitation of the separated efficiency of the photogenerated carriers. This finding provides a simple way to activate the metal-chalcogenides with S-vacancies for optimizing the photocatalytic performance.

Congli Jia,1 Zhengquan Li,2 Dong Guo,1 Zhen Zhang,3 Jingming Yu,4 Guangdong Jiang,1 Xiaobo Xing,3 Shengjun Ji,5 Feng Jin3 1Weifang Medical University, Weifang, People’s Republic of China; 2Department of Laboratory Pathology, People’s Liberation Army 80th Group Military Hospital, Weifang, People’s Republic of China; 3Department of Radiotherapy & Oncology, Qingdao Center Hospital, Qingdao, People’s Republic of China; 4Department of Radiotherapy & Oncology, Shandong Hospital, Jinan, People’s Republic of China; 5Department of Radiotherapy & Oncology, Nanjing Medical University Affiliated Suzhou Hospital, Suzhou, People’s Republic of ChinaCorrespondence: Shengjun JiDepartment of Radiotherapy & Oncology, Nanjing Medical University Affiliated Suzhou Hospital, No. 16 Baita Road, Suzhou 215001, People’s Republic of ChinaEmail drshengjunji@163.comFeng JinDepartment of Radiotherapy & Oncology, Qingdao Center Hospital, No. 127 Siliu Road, Qingdao 266042, People’s Republic of ChinaEmail 1093910079@qq.comBackground: Brain metastases (BM) are severe incidents among patients with non-small cell lung cancer (NSCLC) and have been associated with significant morbidity and decreased survival; thus, new methods are required to improve clinical management. Magnetic resonance spectroscopy (MRS) allows noninvasive measurements of biochemical information from tumor tissue, providing clinically useful imaging biomarkers. The primary aim of this study was to explore the application of MRS in the assessment of tumor prognosis after stereotactic radiotherapy in NSCLC patients with BM.Patients and Methods: MRS was performed on NSCLC patients attending Qingdao Center Hospital with suspected BM, and 68 patients were included in the survival analysis. The qualitative and quantitative parameters of MRS metabolites, such as choline (Cho), creatine (Cr), and N-acetyl-aspartate (NAA), were recorded. To select a cutoff for MRS metabolite parameters in the tumor and to distinguish patients who had recurrence, we performed an ROC curve analysis. Univariate and multivariate Cox regression analyses were used to assess the association between MRS metabolite parameters and clinical cancer prognosis.Results: The average age was 56 years. A total of 68 NSCLC patients underwent metabolic evaluation with single voxel proton MRS and were selected for retrospective analysis. According to the area under the curve (AUC) to predict recurrence, the MRS metabolite parameters were determined as Cho (AUC=0.550), Cr (AUC=0.415), NAA (AUC=0.524), NAA/Cr (AUC=0.600), Cho/Cr (AUC=0.723), and Cho/NAA (AUC=0.543). Cho and Cr predicted poor survival while Cho/Cr and NAA/Cr predicted improved survival (P< 0.05). In the multivariate model with adjustment to establish the potential role of MRS metabolite parameters, Cho/Cr showed a significant association with OS (P=0.009) and PFS (P=0.006) after stereotactic radiotherapy.Conclusion: The positive results of this study indicate the predictive value of metabolic characteristics of BM detected with MRS for the outcome after stereotactic radiotherapy.Keywords: brain metastases, magnetic resonance spectroscopy, stereotactic radiotherapy

Photocatalytic CO2 reduction is a promising technology to mitigate global warming and enrich energy supply. Metal–organic frameworks (MOFs) are prospective photocatalysts for CO2 reduction, but severe charge recombination and limited visible light response largely restrain their applications. As carbon dots (CDs) can act as both electron receptors and photosensitizers, here we propose to develop CD-hybridized MOF photocatalysts for improving their activity for CO2 reduction. In particular, because of the small size of CDs, we have managed to encapsulate CDs inside MOF particles and found that these CD@MOFs exhibit hugely improved photocatalytic activity compared with CD-decorated MOFs or pristine MOFs. Our investigations suggest that placing small CD cocatalysts near the internal metal–oxo clusters of MOFs can help efficient charge transfer and separation in the hybrid photocatalysts, due to the formation of many small heterojunctions among MOFs. The developed CD-hybridized MOF catalysts are characterized in detail and their working mechanism is explored. This work may demonstrate a novel strategy to develop MOF-based hybrid photocatalysts with enhanced photocatalytic activity.

Splitting water into hydrogen (H2) with sunlight is an appealing approach towards alleviating the fossil fuel crisis. However, as one of the most promising light harvesters, colloidal quantum dots (QDs) generally exhibit low photocatalytic activity towards H2 evolution because of the lack of catalytic sites on their surface. Many researchers have focused on activating QDs by anchoring metal complexes on their surface, in which the photoexcited electrons may transfer from the QDs to the metal centres via the organic ligands. These bulky organic ligands usually have poor electrical conductivity and chemical instability, thereby causing high charge recombination and low durability in these QDs/metal complex catalysts. To address these issues, we herein report the doping of cadmium telluride (CdTe) QDs with nickel ions (Ni2+), achieving a remarkable H2 generation rate without the use of co-catalysts. The formation rate of H2 exceeded 27.3 mmol/g/h under visible light irradiation, which is approximately 110-fold higher than that of pristine CdTe QDs. This doping strategy provides a versatile route to reduce protons to H2 with a turnover number of 13,650 in terms of Ni and confer superior durability on the CdTe QDs.

Composite Co-based electrocatalysts exhibit synergetic electrochemical performance and play important role in water-splitting devices. Previous MOF-template route to targeting Co-electrocatalysts relies mainly on regular Co-MOFs particles, and how to obtain hybrid Co-electrocatalysts with adjustable compositions is still challenging. Here we present a facile route to obtain hybrid Co-electrocatalysts with tunable compositions by impregnating different amount of Co2+ ions in common Fe-MOF particles followed by a calcination process. Four different Co-based electrocatalysts with regular porous structures have been developed and their OER activities are investigated. Among them, metallic Co-containing composite electrocatalysts (Co/CoO/CoFe2O4) exhibit both HER and OER activity, and they are applicable to overall water splitting. This work shares a new strategy to achieve porous Co-based composite electrocatalysts and a simple route to tailor their compositions and activities.

Nanoframes (NFs) with highly open structures have attracted substantial attention because of their large surface area, three-dimensional structure and good stability, which are of significance to enhance the catalytic characters. However, it is still challenging to develop facile and efficient method to construct Pt-based NFs with tailored structures. Herein, a simple solvothermal method was developed to prepare monodisperse PtCu dodecahedral nanoframes (PtCu DNFs), where cetyltrimethylammonium chloride (CTAC) served as the structure-director and dispersing agent, oleylamine as reductant, allantoin as the co-structure-director and coreductant. The PtCu DNFs displayed remarkably improved catalytic performances for hydrogen evolution reaction (HER) in both acid and alkaline electrolytes relative to homemade PtCu nanopolyhedrons (NPHs), commercial Pt/C (20 wt%) and Pt black catalysts. The work offers some instructive guidelines for synthesis of novel metallic NFs as efficient HER catalysts.

Inspired by the distinct advantages of BiOCl(001) ultrathin nanosheets being rich in oxygen vacancies (VO) and metal nanoparticles (NPs) with unique surface activity for the adsorption-activation of alcohols, metal-decorated BiOCl(001) ultrathin nanosheets were expected to exhibit enhanced photocatalysis for the selective oxidation of aromatic alcohols. Herein, a small quantity (1.5 wt%) of Au and Pd NPs were loaded on ultrathin BiOCl(001) nanosheets by photodeposition to obtain Au–BiOCl and Pd–BiOCl photocatalysts, respectively. Among the various photocatalysts including BiOCl ultrathin nanosheets, light-irradiated BiOCl ultrathin nanosheets, and metal-decorated BiOCl ultrathin nanosheets, the Pd–BiOCl sample displayed the highest photocatalytic activity for the oxidation of aromatic alcohols to the corresponding aldehydes under ambient conditions. According to a series of experimental analyses as well as the insights from the calculations, the enhanced photocatalysis of Pd–BiOCl was attributed to the remarkable interface cooperation by the electronic coupling between Pd and the BiOCl(001) surface, where the abundant VO sites of BiOCl(001) ultrathin nanosheets and the surface activity of Pd NPs synergistically promote the adsorption-activation of O2 and alcohol molecules as well as facilitating the separation and transfer of photogenerated carriers. These findings highlight the synergistic effect of the metal–semiconductor interface on the photocatalytic oxidation of organic compounds and shed some light on the rational design of highly efficient photocatalysts for selective conversion processes with environmentally benign oxidants like O2.

Upconversion (UC) NaYF4:Yb,Tm nanocrystals (NCs) are capable of converting low-energy near-infrared (NIR) photons to high-energy ultraviolet (UV) and visible (Vis) photons. Integration of NaYF4:Yb,Tm with graphitic carbon nitride (g-C3N4) can extend the spectral response of g-C3N4 to the NIR range. However, photocatalytic activity of NaYF4:Yb,Tm/g-C3N4 is still severely limited by the high recombination rate of photo-generated (PG) electrons and holes (e–/h+) in the g-C3N4. Herein, we report a facile approach to fabricate a ternary nanocomposite consisting of NaYF4:Yb,Tm, TiO2 and g-C3N4. When NaYF4:Yb,Tm NCs were coated with a TiO2 shell and sequentially assembled with g-C3N4 nanosheets (NSs), a semiconductor heterojunction can be fabricated on the UC particles. The as-prepared nanocomposites possess an enhanced photocatalytic activity under Vis and/or NIR lights due to the formation of heterojunction and UC effect. The ternary nanocomposites have been characterized in detail and their photocatalytic mechanism is proposed. Such kind of ternary nanocomposites may provide a new scenario for the design and synthesis of composite photocatalysts for efficiently utilizing the Vis/NIR lights in environmental remedy.

Photocatalytic reduction of CO2 into high value-added CH4 is a promising solution for energy and environmental crises. Integrating semiconductors with cocatalysts can improve the activities for photocatalytic CO2 reduction; however, most metal cocatalysts mainly produce CO and H2. Herein, we report a cocatalyst hydridation approach for significantly enhancing the photocatalytic reduction of CO2 into CH4. Hydriding Pd cocatalysts into PdH0.43 played a dual role in performance enhancement. As revealed by our isotopic labeling experiments, the PdH0.43 hydride cocatalysts reduced H2 evolution, which suppressed the H2 production and facilitated the conversion of the CO intermediate into the final product: CH4. Meanwhile, hydridation promoted the electron trapping on the cocatalysts, improving the charge separation. This approach increased the photocatalytic selectivity in CH4 production from 3.2% to 63.6% on Pd{100} and from 15.6% to 73.4% on Pd{111}. The results provide insights into photocatalytic mechanism studies and introduce new opportunities for designing materials towards photocatalytic CO2 conversion.

Graphitic carbon nitride (g-C3N4) coupled with Bi2WO6 is a promising Type II heterojunction, but it is still difficult to obtain uniform nanocomposites of these materials with the present assembly methods. Here we employ g-C3N4 nanosheets saturated with Bi3+ ions to provide numerous and widespread nucleation sites for the growth of Bi2WO6 nanocrystals. As a result, g-C3N4 nanosheets loaded with fine and controllable amount of Bi2WO6 nanocrystals are produced. The g-C3N4/Bi2WO6 nanocomposites exhibit significantly enhanced photocatalytic activity for RhB degradation under visible-light irradiation. Particularly, the g-C3N4/70 % Bi2WO6 nanocomposite achieves the highest photocatalytic activity, and the average rate constant is almost 5 and 9 times higher than those of bare g-C3N4 and Bi2WO6, respectively. Moreover, the composite exhibits high photocatalytic stability in cycling tests.

There exists a large interlayer pressure difference in the oil wells of the Fuyu oilfield, and the high-pressure layer has a relatively high liquid production. The low-pressure layer is characterized by a relatively low liquid production, and water shut-off is urgently needed. Selective plugging technology is designed to temporarily block the oil layer before plugging the water layer, which is suitable for low-temperature shallow reservoirs. The foaming comprehensive exponent is considered to optimize the formula of the temporary plugging agent, consisting of 200 mL clean water, 0.25% sodium hexadecyl sulfonate, 0.8% sodium carboxymethyl cellulose, and 0.8% soluble starch. In addition, the formula of the multicomponent gel plugging agent is designed via extremum difference analysis, and the formula is 5% acrylamide (AM), 5% acrylic acid (AA), 0.8% PVA, 0.3% N,N-methylenebisacrylamide, 0.1% ammonium persulfate, and 0.2% sodium hydroxide. The selective plugging performance and permeability recovery characteristics of the system are evaluated. The experimental results show that the microfoam temporary blocking agent is more suitable for a core permeability ranging from 100–200 × 10−3 μm2, and the plugging agent can quickly gel at low temperatures. Field tests in a typical well show that the breakthrough pressure gradient of the temporary plugging layer reaches 3.5 MPa/m, thereby effectively protecting the low-pressure layer, and the fluid production of the high-pressure layer is reduced from 13.7 m3/d to 0.6 m3/d, thus realizing the purpose of plugging the high-pressure layer.

The oxygen evolution reaction (OER) is a cornerstone reaction for many renewable energy technologies. Developing low-cost and durable alternatives to precious-metal catalysts with high activity for OER are highly desirable to reduce the processing cost and complexity of renewable energy systems. Recently, metal phosphides based on earth-abundant transition metals, especially bimetallic phosphates have emerged as promising candidates for efficient OER catalysts. The rational design of nanostructured bimetallic phosphates is critical for the practical applications of these electrocatalysts, which requires a well understanding of the composition control and nanocrystal growth process. Herein, we report a facile strategy for the synthesis of novel iron-cobalt bimetallic phosphides (FeCoP) with hollow structures by phosphating Fe (Co)-centered metal-organic frameworks (MOFs). The resultant FeCoP hollow polyhedron, which have large specific surface area providing rich catalytic active sites, show excellent electrocatalytic activity towards OER with low overpotential, small Tafel slope, and remarkable stability. This work provides a new strategy for exploring efficient phosphide catalysts and opens up new avenues for the development of OER catalysts.

Photocatalytic degradation of environmental pollutants by using semiconductor-based photocatalysts offers great potential for remediation of toxic chemicals. For an economical and eco-friendly method to eliminate hexavalent chromium (Cr(VI)), favourable catalysts own high efficiency, stability and capability of harvesting light. Combination of metal with semiconductor is a promising route to improve the photocatalytic performance for Cr(VI) reduction. Herein, well-dispersed platinum (Pt) nanocubes (NCs) were synthesized by a facile one-step hydrothermal method with poly- l -lysine (PLL) as the growth-directing agent, followed by their uniform dispersion on graphitic carbon nitride (g-C3N4). Their morphology, crystal structure, chemical composition, and formation mechanism were mainly characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The hybrid nanocomposite was further explored for photocatalytic reduction of Cr(VI) to trivalent chromium (Cr(III)) under visible light at room temperature, by using formic acid (HCOOH) as a reducing agent, showing great improvement in photocatalytic activity and reusability, outperforming the referenced g-C3N4 and home-made Pt black/g-C3N4 catalysts. The effects of various experimental parameters and the proposed mechanism are discussed in detail.

The combination of a metal with a semiconductor is a promising route to improve the solar-to-chemical conversion efficiency of photocatalysts. In this article, ultrathin Pd nanosheets are integrated with semiconductor TiO2 nanosheets for photocatalytic hydrogen evolution, which acts as a cocatalyst and plasmonic agent in ultraviolet and visible-near-infrared spectral regions, respectively. Owing to the unique two-dimensional (2D) nanostructure, the Pd nanosheet cocatalyst realizes the large TiO2–Pd interfacial area for electron transfer as well as a large Pd exposed area for reduction reactions, while the plasmonic Pd nanosheets offer strong vis-NIR light absorption for “hot” electron production as well as a large interfacial area for “hot” electron injection. As a result, the Pd nanosheets achieve improved photocatalytic activity in comparison with three-dimensional Pd nanotetrahedrons under both light irradiations. This work underlines the importance in choosing a suitable shape of metal in the surface and interface design of semiconductor–metal hybrid photocatalysts as well as the advantages of 2D metal nanostructures in realizing high photocatalytic performance.

In this work, we described a facile one-pot hydrothermal process developed to synthesize CdS/C core–shell nanospheres successfully. The as-prepared CdS/C core–shell nanospheres are with 100 nm in diameter and the amorphous carbon shell is with several nanometers in thickness. The phase, morphology and structures of the samples were investigated by X-ray power diffraction (XRD) analyses, field-emission scanning electron microscopy (FESEM, JEOL-6700F) and transmission electron microscopy (TEM, JEOL 3010); respectively. The as-prepared CdS/C core–shell nanospheres showed enhanced photocatalytic properties and photostability compared to the single counterpart of CdS nanospheres owing to the efficiently separation of photogenerated electrons (e − ) and holes (h + ) derived from the photocatalyst. In addition, the as-prepared CdS/C core–shell nanospheres might find wide application in wastewater treatment, solar cells, lithium ion batteries, etc.

Carbon-coated nickel-doped-ZnO nanorods (Ni/ZnO@C NRs) are successfully prepared for the purpose of improving the visible-light photocatalytic performance of ZnO by expanding the absorption in the visible-light region and increasing the separation efficiency of photogenerated charges. The physicochemical properties of the catalysts were characterized using SEM, TEM, XRD, and Raman, FT-IR, UV-vis diffuse reflectance and PL spectra. The results indicated that nickel ions substituted for Zn2+ in the lattice of ZnO, whereas all the carbon was uniformly coated on the surface of the nanorod photocatalysts. Among the Ni/ZnO@C samples with different ion-doping levels and carbon coating content, the 1.0 mol% Ni/ZnO@C-3 sample possessing a carbon layer thickness of 3.8 nm exhibited a higher visible light activity and synergistic effects of the nickel and carbon, which were responsible for improving the photocatalytic activity. By using the hydrothermal carbon layer as a sacrificial template, nanovoid core–shell structured Ni/ZnO@void@SiO2 was obtained through subsequent silica coating and calcination reactions. Its porous shell could adsorb dye molecules from the bulk solution and accumulate them in the void space where the Ni/ZnO core is more accessible than for the bare Ni/ZnO nanorods in bulk solution, meanwhile the nanovoid structure could also avoid shielding of the catalyst-active sites by the outer layer, which leads to a significant photocatalytic activity enhancement. In addition, antibacterial studies of Ni/ZnO@void@SiO2 under sunlight irradiation were performed against Escherichia coli. This nanovoid photocatalyst exhibited high inhibition of the Gram-negative bacterial strain with co-action of the surface adsorption of the mesoporous SiO2 and the strong oxidation abilities of the formed reactive oxygen species.

High-quality hexagonal NaYF4:Yb,Tm upconversion nanocrystals (UCNs) prepared in organic solutions display uniform sizes and strong UC emissions, but they possess a hydrophobic surface which hinders combining them with various semiconductor nanocrystals (NCs) to form a hybrid NIR-activated photocatalyst. Herein we present a facile approach to modify hydrophobic UCNs with a uniform carbon layer and enable them with hydrophilicity and surface functionalization. The carbon shell provides a good substrate for enriching with metal ions and in situ generation of CdS nanoclusters on the particle surface which can utilize both the upconverted UV and visible emissions. The developed NaYF4:Yb,Tm@C@CdS nanoparticles are characterized with TEM, SEM, XRD, PL and UV-Vis spectra and their formation mechanism is elucidated. The products display good photocatalytic activity under visible light and obviously enhanced performance under Vis-NIR light, due to the efficient utilization of UC emissions and the strong adsorption capacity of the carbon shell. The working mechanism of the hybrid photocatalysts is also proposed.

Development of magnetic visible-light-driven photocatalysts is desirable to the practical application of photocatalyts for collection and recycling use. Here we present a facile approach to synthesize Fe3O4@C@CdS magnetic photocatalysts which can avoid multi-step preparation process. Through one-step solvothermal carbonization of ferrocene, the produced carbon-coated Fe3O4 clusters can serve as both magnetic cores and deposition substrates for in situ generating crystalline CdS nanocrystals on them by rapid microwave irradiation. The prepared Fe3O4@C@CdS nanoparticles exhibit a uniform core–shell structure and display good photocatalytic activity and recyclability in the degradation of organic dyes. These magnetic photocatalysts may find potential application in wastewater treatment for the future environment remedy.

Core–shell nanostructures are of great scientific and technological importance owing to their enhanced physical and chemical properties. In this work, we report a facile synthesis of unusual Ag/TiO2 (B) hierarchical core–shell nanowires with 200 nm in diameter and tens of micrometers in length for the first time. The hierarchical core–shell nanowires of Ag/TiO2 have been achieved from silver nitrate, tetrabutyl orthotitanate and ethylene glycol via a synergistic soft-hard template method. Each of the hierarchical core–shell nanowires of Ag/TiO2 is comprised of Ag nanowires with 50–70 nm in diameter and sheath comprised of ultrathin nanosheets of monoclinic β-TiO2 with several nanometers in thickness and preferential exposure of (010) facet. Several experimental observations illustrate that temperature and amount of tetrabutyl orthotitanate play key roles in formation of this kind of hierarchical core–shell nanostructures. As expected, the hierarchical core–shell nanostructures exhibited enhanced photocatalytic performance on degradation towards RhB. In particular, the as-prepared Ag/TiO2 core–shell nanowires exhibit superior, durable bacteriostatic and bactericidal properties.

Because of the limited penetration depth of visible light that generally excites most of the available photosensitizers (PSs), conventional photodynamic therapy (PDT) is limited to the treatment of superficial and flat lesions. Recently, the application of deep penetrating near-infrared (NIR) light excitable upconversion nanoparticles (UCNs) in conjunction with PDT has shown to have clear potential in the treatment of solid tumors due to its ability to penetrate thick tissue. However, various constructs developed so far have certain limitations such as poor or unstable PS loading, reducing their therapeutic efficacy and limiting their application to solution or cell-based studies. In this work, we present a method to fabricate uniform core-shell structured nanoconstruct with a thin layer of photocatalyst or PS-titanium dioxide (TiO2) stably coated on individual UCN core. Our design allows controllable and highly reproducible PS loading, preventing any leakage of PS compared to previously developed nanoconstructs, thus ensuring repeatable PDT results. Further surface modification of the developed nanoconstructs with polyethylene glycol (PEG) rendered them biocompatible, demonstrating good therapeutic efficacy both in vitro and in vivo.

Synthesis of N-doped TiO2 hollow spheres with a small grain size, large surface area and high degree of crystallinity is favorable to achieve an overall high photocatalytic activity. But traditional synthetic approaches generally involve many tedious steps and are time-consuming. Here we present a facile method to synthesize N-doped TiO2 hollow spheres using organic silane-doped silica nanoparticles as templates. The organic–inorganic silica can be simultaneously etched during the deposition of TiO2 shell to create a thin silica layer on the TiO2 surface. Such a thin silica layer can efficiently protect the TiO2 nanocrystals from growing larger during high-temperature calcination. At the same time, the organic silane can serve as a nitrogen source to be doped in the TiO2 shell. The developed silica-protected and N-doped TiO2 hollow spheres can be directly employed as photocatalysts without SiO2 etching and show obvious light utilization in both UV and visible bands.

Nickel-doped zinc oxide hollow nanospheres have been synthesized using a simple solvothermal approach through a morphological transformation driven by a localized Ostwald ripening process. The saturation magnetization of the system shows that the materials have only a short-range magnetic ordering in them. Based on the visible-light photocatalytic experiment, we could confirm that, with a high doping content (10 mol%), the doping accompanied with increased recombination which reduced the energy of photoinduced electron leading to suppressed photocatalytic activity. Changing reaction parameters, i.e. the mixed reactant concentration, doping content, and different solvents, Zn1−xNixO powders exhibited the elongated prismatic form with sharp tips, quasi-spherical structure, and hexagonal-based polyhedron, respectively. The photocatalytic results demonstrate that different crystal growth orientations, specific surface areas, particle size distributions, and doping levels have strong influences on the photocatalytic activity performances. Among the samples, hexagonal-based polyhedrons have the best photodegradation efficiency standing on higher fraction of exposed polar facets, larger specific surface area, as well as an optimal doping level. The 1 mol% nickel content showed the best photocatalytic activities among the nickel-doped zinc oxide samples.

Gold nanocrystals (NCs) supported on silica spheres or encapsulated in thin silica shells both have their own merits for catalytic applications. Development of sandwich nanostructures is a good solution to combine their advantages for recycling. Herein, we present a facile route to synthesize SiO2@Au@r-SiO2 (‘r-’ means redeposition) nanoparticles (NPs) using organic–inorganic silica spheres as templates. It is interesting to find that a thin silica layer can be spontaneously redeposited during the growth of Au NCs on the templates by partially etching the organic–inorganic silica spheres. The number of Au NCs embedded in the sandwich structures can be facilely controlled by adjusting the amount of HAuCl4 solution added. The effect of Au particle number on their catalytic activity in these SiO2@Au@r-SiO2 NPs has been evaluated by the reduction of p-nitrophenol. The developed SiO2@Au@r-SiO2 NPs show controllable activity in the dark and enhanced activity under visible light due to the localized surface plasmon resonance (LSPR) of Au NCs.

Combination of upconversion nanocrystals (UCNs) with CeO2 is a decent choice to construct NIR-activated photocatalysts for utilizing the NIR light in the solar spectrum. Herein we present a facile approach to deposit a CeO2 layer with controllable thickness on the plate-shaped NaYF4:Yb,Tm UCNs. The developed core–shell nanocomposites display obvious photocatalytic activity under the NIR light and exhibit enhanced activity under the full solar spectrum. For enhancing the separation of photogenerated electrons and holes on the CeO2 surface, we sequentially coat a ZnO shell on the nanocomposites so as to form a heterojunction structure for achieving a better activity. The developed hybrid photocatalysts have been characterized with TEM, SEM, PL, etc., and the working mechanism of such UCN-semiconductor heterojunction photocatalysts has been proposed.

α-Fe 2 O 3 nanoparticles-decorated ZnO nanorod-assembled hollow spheres were successfully synthesized by a simple acetone-assisted impregnation deposition. SEM images showed a uniform distribution of α-Fe 2 O 3 nanoparticles not only on the surfaces of ZnO spheres but also inside pores of ZnO parallel aligned nanorods. The α-Fe 2 O 3 /ZnO binary semiconductor composites exhibited a superior visible-light photocatalytic activity for degradation of rhodamine B (RhB) as compared with pure ZnO spheres. The enhancement was attributed to stronger visible light absorption ability and effective photogenerated charge separation of α-Fe 2 O 3 /ZnO composites.

Glucose oxidase (GOx) can react with intracellular glucose and oxygen (O2 ) to produce hydrogen peroxide (H2 O2 ) and gluconic acid, which can cut off the nutrition source of cancer cells and consequently inhibit their proliferation. Therefore, GOx is recognised as an ideal endogenous oxido-reductase for cancer starvation therapy. This process can further regulate the tumor microenvironment by increasing the hypoxia and the acidity. Thus, GOx offers new possibilities for the elaborate design of multifunctional nanocomposites for tumor therapy. However, natural GOx is expensive to prepare and purify and exhibits immunogenicity, short in vivo half-life, and systemic toxicity. Furthermore, GOx is highly prone to degrade after exposure to biological conditions. These intrinsic shortcomings will undoubtedly limit its biomedical applications. Accordingly, some nanocarriers can be used to protect GOx from the surrounding environment, thus controlling or preserving the activity. A variety of nanocarriers including hollow mesoporous silica nanoparticles, metal-organic frameworks, organic polymers, and magnetic nanoparticles are summarized for the construction of GOx-based nanocomposites for multimodal synergistic cancer therapy. In addition, current challenges and promising developments in this area are highlighted.

Spherical superparticles consisting of small NaYF4:Yb, Er nanocrystals are developed with an emulsion method. Within each superparticle, many individual upconversion nanocrystals are condensed together and lots of small vacancies are simultaneously produced because of the packing of primary nanocrystals. Through the loading fluorescent dyes inside the vacancies of these superparticles during assembly, one can fine-tune the upconversion fluorescence of these superparticles. Nearly single-band red upconversion emission can also be achieved by loading suitable amounts of dyes in these superparticles.

We have developed a facile method to synthesize upconversion YF3:Yb,Tm nanocrystals in ethylene glycol. These nanocrystals exhibit an assembly structure with a peanut-like appearance. A layer of TiO2 shell can be facilely coated on the YF3:Yb,Tm nanocrystals via a sol–gel process and crystallized through annealing. The developed YF3:Tb,Tm@TiO2 particles show good photocatalytic activity under the UV band and work better in the UV/NIR band of a Xe lamp, as the core particles can efficiently upconvert NIR light into UV one.

YF3 is an important host matrix for lanthanides doping to give both strong down- and up-conversion luminescence with high quantum efficiency. Controlled synthesis of YF3 nanocrystals is an efficient route to obtain different YF3 nanocrystals satisfying for different applications and controlling their fluorescence. Here we present a facile approach to selectively synthesize different YF3 nanocrystals using ethylene glycol (EG) as solvent. Five distinct morphologies can be conveniently obtained through changing the fluoride sources and chelating ligands in the EG solution. The prepared products were characterized and their formation mechanisms were proposed. After doped with different lanthanides, these samples can give both down- and up-conversion luminescence, suggesting that they are good nanoparticulate hosts. A comparison of fluorescent intensities between different products has been made, offering us an opportunity to study the relationship between fluorescence intensities and morphologies of YF3 nanostructures. Our results suggest that formation of assemblies is a feasible way to enhance the fluorescence of lanthanide nanocrystals in addition to the size control.

The diverse biological effects of nanomaterials form the basis for their applications in biomedicine but also cause safety issues. Induction of autophagy is a cellular response after nanoparticles exposure. It may be beneficial in some circumstances, yet autophagy-mediated toxicity raises an alarming concern. Previously, it has been reported that upconversion nanoparticles (UCNs) elicit liver damage, with autophagy contributing most of this toxicity. However, the detailed mechanism is unclear. This study reveals persistent presence of enlarged autolysosomes in hepatocytes after exposure to UCNs and SiO2 nanoparticles both in vitro and in vivo. This phenomenon is due to anomaly in the autophagy termination process named autophagic lysosome reformation (ALR). Phosphatidylinositol 4-phosphate (PI(4)P) relocates onto autolysosome membrane, which is a key event of ALR. PI(4)P is then converted into phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2 ) by phosphatidylinositol-4-phosphate 5-kinase. Clathrin is subsequently recruited by PI(4,5)P2 and leads to tubule budding of ALR. Yet it is observed that PI(4)P cannot be converted in nanoparticle-treated hepatocytes cells. Exogenous supplement of PI(4,5)P2 suppresses the enlarged autolysosomes in vitro. Abolishment of these enlarged autolysosomes by autophagy inhibitor relieves the hepatotoxicity of UCNs in vivo. The results provide evidence for disrupted ALR in nanoparticle-treated hepatocytes, suggesting that the termination of nanoparticle-induced autophagy is of equal importance as the initiation.

Recent advances in photocatalysis highlight the important role of cocatalysts in improving the solar-to-chemical conversion efficiency for various reactions, such as water splitting and CO2 reduction reactions. Given that cocatalysts play two important roles, in charge trapping and surface reactions, the rational material design of cocatalysts would be an effective route in pursuing their maximum contribution to the performance of photocatalysts. In this review, we aim to outline the recent progress of surface and interface design in cocatalysts for photocatalytic water splitting and CO2 reduction. We first introduce the surface design of cocatalysts, which enables the enhancement of specific water splitting or CO2 reduction reactions through surface parameter (e.g., the composition, facets and phases) adjustments. We then present key parameters for designing the interface between photocatalyst and cocatalyst, which offer a set of versatile options for tuning the charge transfer to the cocatalyst. Taken together, the surface and interface of cocatalysts may have synergetic effects on the photocatalytic performance, which are discussed to provide guidance for simultaneously tailoring surface and interface parameters. Finally, we summarize the challenges and opportunities for the surface and interface design of cocatalysts for the efficient production of solar fuels.

The induction of autophagy on exposure of cells to a variety of nanoparticles represents both a safety concern and an application niche for engineered nanomaterials. Here, we show that a short synthetic peptide, RE-1, identified by means of phage display, binds to lanthanide (LN) oxide and upconversion nanocrystals (UCN), forms a stable coating layer on the nanoparticles' surface, and effectively abrogates their autophagy-inducing activity. Furthermore, RE-1 peptide variants exhibit a differentially reduced binding capability, and correspondingly, a varied ability to reduce the autophagic response. We also show that the addition of an arginine-glycine-aspartic acid (RGD) motif to RE-1 enhances autophagy for LN UCN through the interaction with integrins. RE-1 and its variants provide a versatile tool for tuning material-cell interactions to achieve the desired level of autophagy, and may prove useful for the various diagnostic and therapeutic applications of LN-based nanomaterials and nanodevices.

Synthesis of well-defined sodium yttrium fluoride (NaYF4) nanocrystals has been achieved in nonpolar solvents, but these nanocrystals possess a hydrophobic surface and need to be surface-modified for various biological applications. Development of facile aqueous solution method to synthesize one-dimensional NaYF4 with a hydrophilic surface still remains challenging. Herein, we demonstrate a simple route to prepare hydrophilic NaYF4 nanorods by using hydrophobic NaYF4 nanospheres as precursor. It is interesting to find that hydrothermal treatment of oleic acid-capped NaYF4 nanocrystals can not only induce anisotropic growth of these nanocrystals but also change their surface properties. The hydrophilic NaYF4 nanorods synthesized in this work has been well characterized and possible formation mechanism has also been discussed.

Here we present a microemulsion route to prepare core-shell structured NaGdF4:Yb,Er@Carbon nanoparticles, in which a thin layer of hydrophilic carbon was covered on hydrophobic NaGdF4:Yb, Er nanocrystals. The prepared NaGdF4:Yb,Er@Carbon nanoparticles were uniform in a size of 25 nm, water-dispersible, and displayed good biocompatibility and strong upconversion fluorescence. Their potential for use as efficient cell-imaging probes is also demonstrated.

This manuscript describes the accurate coating of CdS nanoparticles on the surface of colloidal carbon spheres by a facile two-step, microwave-assisted method and the studies on the photocatalytic activity of the C@CdS core-shell spheres. For the coating of CdS nanoparticles, cadmium ions were incorporated into the hydrophilic shell of colloidal carbon spheres and reacted with an introduced sulfur source under a microwave field to obtain the C@CdS hybrid spheres. Using this process, the as-prepared hybrid structures preserved the good dispersity and uniformity of initial carbon spheres, and the thickness of the CdS nanoparticles shell could be varied or controlled by the irradiation time. A photoluminescence spectrum showed that the C@CdS hybrid spheres feature a broad green emission at around 494 nm (λ(ex) = 337 nm). Additionally, CdS nanospheres were successfully prepared in aqueous solution via a microwave-assisted route, and the effect of irradiation time on the products was also investigated. The studies of the photocatalytic property demonstrate that these fabricated functional hybrid structures evinced a higher photocatalytic degradation activity when exposed to visible light irradiation than that of CdS nanospheres under the same conditions.

Uniform ZnO/ZnFe2O4 fluorescent magnetic composite hollow nanopsheres can be successfully fabricated using carbonaceous nanospheres as templates, which are synthesized via a hydrothermal approach. The ZnO/ZnFe2O4 composited nanoarchitectures show fluorescent and magnetic properties for improved physical and chemical properties for electronics, magnetism, optics, and catalysis compared with their single counterparts and may find potential applications in many fields, such as catalyst supports, catalysis, drug delivery, chemical/biological separation, sensing, and so on. This method may be extended to synthesize some other binary/ternary metal oxide composite hollow nanoarchitectures.

An efficient near-infrared (NIR) quantum cutting (QC) in Ce 3+ , Yb 3+ co-doped YBO 3 phosphors has been demonstrated, which involves the emission of two low-energy NIR photons (around 973 nm) from an absorbed ultra-violet (UV) photon at 358 nm via a cooperative energy transfer (CET) from Ce 3+ to Yb 3+ ions. Yb 3+ concentration dependent quantum efficiency has been calculated and the maximum efficiency approaches up to 175% before reaching the critical concentration quenching threshold. The development of NIR QC Ce 3+ , Yb 3+ co-doped phosphors may open up a new approach to achieve high efficiency silicon-based solar cells by means of downconversion.

Despite plenty of reports on the preparation of Au nanorods, it remains challenging to grow uniform Au nanorods with diameters below 5 nm. In this communication, we demonstrate the facile synthesis of ultrathin Au nanorods with a uniform diameter of 2 nm and an average aspect ratio of 30. The synthesis involves the room-temperature aging of a mixture of the [AuCl(oleylamine)] complex with amorphous Fe nanoparticles in chloroform. Analysis of the growth mechanism indicates that Au nanoparticles with a high density of defects were formed at early stages, followed by etching and redeposition process that gradually led to the growth of ultrathin Au nanorods along the ⟨111⟩ direction. This growth mechanism is different from the mechanism recently reported for ultrathin Au nanowires (ref 26), where the [AuCl(oleylamine)] complex is assembled into polymer chains followed by reduction to form wires, although the template effect of oleylamine for the formation of ultrathin Au nanorods cannot be completely ruled out.

Treatment of the chronic hepatitis C virus (HCV) infection is an unmet medical need, and the HCV NS3 serine protease (NS3-SP) has been used as an attractive target of antiviral screening against HCV. To find naturally chemical entities as lead compounds from which novel anti-HCV agents could be developed, bioassay-guided fractionation and isolation were performed on a crude ethanol extract from rhizomes of the Chinese medicinal herb Rhodiola kirilowii (Regel) Maxim using column chromatography (CC) techniques and in vitro inhibitory activity against HCV NS3-SP. The partition of the extract between water and different organic solvents led to the isolation and identification of 12 compounds in the ethyl acetate part which proved to be the most active. These compounds were tested for in vitro activity against HCV NS3-SP, among which four (-)-Epicatechin derivatives: 3,3'-Digalloylproprodelphinidin B2 (Rhodisin, 1); 3,3'-Digalloylprocyanidin B2 (2); (-)-Epigallocatechin-3-O-gallate (EGCG, 3); and (-)-Epicatechin-3-O-gallate (4, ECG) represented the most potent ones with IC(50) of 0.77, 0.91, 8.51, and 18.55 microM, respectively. Salidroside, the commonly known compounds, together with the other compounds showed no activity up to 100.0 microM. Methylation and acylation of the hydroxyl groups of 1-4 caused a decrease of activity. Cell viability and secreted alkaline phosphatase (SEAP) activity assays with 1-4 revealed little if any toxicity. These nonpeptide inhibitors of HCV NS3-SP might serve as potential candidate anti-HCV agents.