Specific targeting of tumor tissues is essential for tumor imaging and therapeutics but remains challenging. Here, we report an unprecedented method using synthetic sulfonic-graphene quantum dots (sulfonic-GQDs) to exactly target the cancer cell nuclei in vivo without any bio- ligand modification, with no intervention in cells of normal tissues. The key factor for such selectivity is the high interstitial fluid pressure (IFP) in tumor tissues, which allows the penetration of sulfonic-GQDs into the plasma membrane of tumor cells. In vitro, the sulfonic-GQDs are repelled out of the cell membrane because of the repulsive force between negatively charged sulfonic-GQDs and the cell membranes which contributes to the low distribution in normal tissues in vivo. However, the plasma membrane-crossing process can be activated by incubating cells in ultrathin film culture medium because of the attachment of sulfonic-GQDs on cell memebranes. Molecular dynamics simulations demonstrated that, once transported across the plasma membrane, the negatively charged functional groups of these GQDs will leave the membrane with a self-cleaning function retaining a small enough size to achieve penetration through the nuclear membrane into the nucleus. Our study showed that IFP is a previously unrecognized mechanism for specific targeting of tumor cell nuclei and suggested that sulfonic-GQDs may be developed into novel tools for tumor-specific imaging and therapeutics.

Nanomaterials have attracted considerable interest owing to their unique physicochemical properties. The wide application of nanomaterials has raised many concerns about their potential risks to human health and the environment. Metal oxide nanoparticles (MONPs), one of the main members of nanomaterials, have been applied in various fields, such as food, medicine, cosmetics, and sensors. This review highlights the bio-toxic effects of widely applied MONPs and their underlying mechanisms. Two main underlying toxicity mechanisms, reactive oxygen species (ROS)- and non-ROS-mediated toxicities, of MONPs have been widely accepted. ROS activates oxidative stress, which leads to lipid peroxidation and cell membrane damage. In addition, ROS can trigger the apoptotic pathway by activating caspase-9 and -3. Non-ROS-mediated toxicity mechanism includes the effect of released ions, excessive accumulation of NPs on the cell surface, and combination of NPs with specific death receptors. Furthermore, the combined toxicity evaluation of some MONPs is also discussed. Toxicity may dramatically change when nanomaterials are used in a combined system because the characteristics of NPs that play a key role in their toxicity such as size, surface properties, and chemical nature in the complex system are different from the pristine NPs.纳米材料由于其独特的性质已经被广泛应用于很多领域, 但随着纳米材料的大规模制备和广泛应用, 它对环境以及人类的潜在危害越来越引起人们的重视. 金属氧化物纳米颗粒(MONPs)作为一类纳米材料大量地用于食品、医药、化妆品、传感器等领域. 因此, MONPs的生物毒性研究至关重要. 本文主要对目前应用最为广泛的几种MONPs (纳米二氧化钛、氧化锌、氧化铁等)生物毒性的研究及其毒性机理做了总结. MONPs导致毒性的机制有两个方面: ROS介导的毒性和非ROS介导的毒性. ROS激活氧化应激, 导致脂质过氧化, 引起细胞膜损伤, 此外, ROS可以激活caspase-9和caspase-3, 触发凋亡通路. 非ROS介导的毒性机制, 包括MONPs释放的离子引起的毒性, 纳米粒子在细胞表面的粘附以及与特定的死亡受体的相互作用. 此外, 由于当纳米材料处于一个复杂的体系中时, 它自身的性质, 包括尺寸、粒径、表面化学性质等都会发生变化, 我们对一些MONPs的复合毒性也做了讨论.

Facile carbon–carbon bond formation was achieved through the dehydrogenation coupling of acetone at the α-position. Using the H2O2/UV-light system, the acetonyl radicals that were formed from the selective cleavage of the α-C–H bond of acetone underwent a C–C coupling reaction. By modulating the instantaneous concentration of hydrogen peroxide, the direct C–C coupling of acetone was achieved. Moreover, the selectivity and generation rate of 2,5-hexanedione reached 67.4% and 8.6 mmol h−1, respectively.

•The all-carbon ternary flexible electrodes have been fabricated by the electrode deposition of nitrogen and oxygen co-doped single-crystalline GQDs.•The flexible electrodes deliver ultrahigh specific capacitance (461 mF cm−2) by inducing a high concentration of active nitrogen and oxygen at edge.•Symmetrical N-O-GQD/CNT/CC all-solid-state flexible supercapacitors offer energy density up to 32 μWh cm−2 and demonstrate the good stability, high flexibility, and folding ability under different deformations.•Nitrogen and oxygen co-doped GQDs can function as a highly active, solution-processable pseudocapacitive materials applicable to high-performance supercapacitors.We present a novel approach for hierarchical fabrication of high-performance, all-solid-state, flexible supercapacitors from environmentally friendly all-carbon materials. Three-dimensional carbon nanotube/carbon cloth network (CNT/CC) is used as a conductive, flexible and free-standing scaffold for the electro-deposition of highly N/O co-doped graphene quantum dots to form the high-activity, all-carbon electrodes. The hierarchical structure of the CNT/CC network with high electrical conductivity and high surface area provides improved conductive pathways for the efficient activation of GQDs with high pseudocapacitance and electrical double layer capacitance. The obtained N-O-GQD/CNT/CC electrodes for all-solid-state flexible supercapacitors exhibit an ultrahigh areal capacitance of up to 461 mF cm−2 at a current density of 0.5 mA cm−2, while keeping high rate and cyclic performances. This work highlights the great potential of highly active GQDs in the construction of high-performance flexible energy-storage devices.Download high-res image (191KB)Download full-size image

Nowadays, rattle-like or so-called yolk-shell nanostructures have set off a new wave of research in view of their prominent features including large surface area, tunable void and flexible functional core, etc. Herein, rattle-like mesoporous silica nanoparticles (RMSNs) with a pure silica core, a hollow cavity and a mesoporous shell have been successfully fabricated via a surfactant-assisted selective etching strategy. The synthetic approach involves the preparation of solid silica spheres with three-layer different structural silica containing the inner core of pure silica, middle layer of hybrid silica and outer shell of surfactant/SiO2 composite, followed by a hydrothermal treatment in hot water. The resulting products show a distinct rattle-like structure and spherical morphology. The average diameter, the shell thickness, and the solid core size of RMSNs are about 290, 35 and 90 nm, respectively. During the etching process, the surfactant with different length of alkyl chain (CnTAB, e.g. cetyltrimethylammonium bromide) in outer shell plays a decisive role for the formation of rattle-like structure. Benefiting from the residual amino groups in RMSNs, Au@RMSNs composites can be further constructed by in-situ generating Au nanoparticles into their hollow cavity, demonstrating an excellent catalytic performance for reduction of 4-nitrophenol. Additionally, RMSNs also show a strong ability for adsorption of rhodamine B.Download high-res image (57KB)Download full-size image

•Visible-light driven photocatalyst with macroscopic architecture is fabricated by crystalline g-C3N4 and graphene nanosheets.•The composite is mechanically robust and conveniently recyclable.•The photocatalyst exhibits excellent photodegradation performance on MO and MB, as well as photoreduction on bromate.•The interaction between composite and organic compounds is proven as π-π adsorption.Herein, a g-C3N4/GO aerogel hybrid with macroscopic 3D architecture is fabricated and applied in visible-light-induced water mediation. The composite photocatalyst with compressibility and recyclability is extraordinarily suitable for practical application. The morphologies and properties are carefully characterized, suggesting g-C3N4 is well decorated on the surface of GO by π-π stacking and the GO sheets are well interlaced. A moderate amount of g-C3N4 in the hybrid is beneficial to photocatalytic activity for dyes and bromates. When the mass ratio of g-C3N4 and GO is 3:5, the % degradation of MO and MB (20 mg L−1) can reach ∼90% in 40 min visible-light illumination, and%conversion of bromate (250 μg L−1) can be obtained almost 80% in 60 min illumination. Underlying premise of maintaining intact macro appearance, the photocatalytic performance of the hybrid scarcely any lowers after 5 successive runs on degradation of MO, and the mass loss is below 4%. The composite mainly interacts with the contaminants by π-π adsorption, implying it can be an important broad-spectrum photocatalyst since most of the contaminants in the environments contain π-bond structure. Through scavenger experiments and ESR determination, peroxide radical anions are proven as the predominant species during the photodegradation processes.Download high-res image (151KB)Download full-size image

•GQD/BiVO4 composites could significantly enhance the solar-driven photocatalytic activities for CBZ.•Multi-factors influencing degradation process were investigated.•Potential transformation products during the degradation process were tentatively identified.•Hydroxylation or cleavage of amide group on the heterocycle may be the main initial photocatalytic degradation channels.Herein, solar-driven GQDs loaded BiVO4 heterostructure catalysts were fabricated and employed to degradate carbamazepine (CBZ) under simulated solar light. The as-prepared ternary catalysts (GQD/m-BiVO4/t-BiVO4) were thoroughly characterized by TEM, HRTEM, XRD, XPS, UV-vis, Raman and PL. The characterization results demonstrated that GQDs are well-dispersed on binary BiVO4 support, and the optical properties of the composites are improved with GQDs loaded. The photocatalytic activities of the novel composite catalysts were significantly increased by incorporation of GQDs on original BiVO4 semiconductor. In particular, the 1.0 wt% GQD loaded catalysts exhibited the highest photocatalytic activity for CBZ, and the mineralization degree of CBZ with the catalysts could achieve more than 95%. In addition, the transformation products (TPs) of CBZ during the catalysis processes were tentatively identified, and hydroxyl radicals were regarded as the predominant active species. From the results of density functional theory (DFT) calculations and evolution of TPs, hydroxylation and cleavage of amide group on the heterocycle may be the main initial photocatalytic degradation channels for CBZ under the catalysis of GQD/BiVO4.Download high-res image (283KB)Download full-size image

A novel adsorbent of AgBr–AgBr/CTAB nanomaterials, which was synthesized via Tollen’s reagent with the aid of hexadecyltrimethy ammonium bromide (CTAB), showed an excellent high affinity to anions and was used for removal of organic dyes in aqueous solutions. The synthesized AgBr–AgBr/CTAB was thoroughly characterized by XRD, SEM, TEM, XPS, FTIR, TGA, DLS as well as zeta potential measurements. The adsorption property and capacity of AgBr–AgBr/CTAB for organic dyes were evaluated using methylene blue (MB), rhodamine B (RhB), acid red 18 (AR-18), orange G (OG), indigo carmine (IC), and methyl orange (MO) as models. The adsorption capacity of AgBr–AgBr/CTAB complex toward four anionic dyes OG, AR-18, IC, and MO solutions was 87.43 ± 2.03 mg g–1, 205.89 ± 2.12 mg g–1, 140.42 ± 2.13 mg g–1, and 104.6 ± 1.59 mg g–1, respectively. On the other hand, this adsorbent exhibited little adsorption ability toward two cationic dyes, MB (2.99 ± 0.40 mg g–1) and RhB (2.96 ± 0.60 mg g–1). Interestingly, AgBr–AgBr/CTAB could be applied to efficiently adsorb anionic dyes from binary cationic–anionic dye systems with a high separation factor, and such adsorbent could be reused at least 5 times with adsorption capacities above 95%. The removal of anionic dyes followed pseudo-first-order kinetics and Langmuir isotherm model, indicating that anionic dyes were monolayerly adsorbed on our as-prepared materials. To further elucidate the adsorption mechanism, the theoretical calculation based on first-principles was also provided. The results suggested R-SO3– groups were the active sites and electrostatic attraction was the dominating contribution for the adsorption of anionic dyes.Keywords: AgBr; Anionic dyes; CTAB; Kinetic and isotherm models; Selective adsorption

•Amine-enriched porous carbon electrodes have been fabricated by the electrostatic fusion of amine-functionalized single-crystalline GQDs.•The carbon films deliver ultrahigh specific capacitance (400–595 F g−1) by inducing a high concentration of active amine moieties at edge.•GQD supercapacitors offer energy density up to 21.8 Wh kg−1 and retain 90% of the initial capacitance after 10,000 cyclic voltammetry tests.•Amine-enriched GQDs can function as a highly active, solution-processable pseudocapacitive materials applicable to high-performance supercapacitors.The applications of carbon-based supercapacitors have been limited by their low energy storage density owing to their limited active storage sites. To overcome this limitation, amine-enriched porous carbon electrodes have been fabricated by the electrostatic fusion of amine-functionalized single-crystalline graphene quantum dots (GQDs) within conductive, vertically ordered TiO2 nanotube arrays as the collectors. The carbon films deliver ultrahigh specific capacitance (400–595 F g−1) even beyond the theoretical upper limit of single-layer graphene by inducing a high concentration of active amine moieties at edge. Symmetrical GQD supercapacitors in H2SO4 electrolyte offer energy density up to 21.8 Wh kg−1 and retain 90% of the initial capacitance after 10000 cyclic voltammetry tests. The results show that amine-enriched GQDs can function as a new kind of highly active, solution-processable, and low-cost pseudocapacitive materials applicable to high-performance supercapacitors.

Upconversion nanocrystals (UCNCs) hold promise for bioimaging, solar cells, photocatalysis and volumetric displays. However, their upconversion luminescence intensities are usually low due to the weak and narrowband near-infrared absorption of lanthanide ions. Herein, we introduce and validate a strategy to hugely enhance upconversion luminescence intensity by using an organic near-infrared dye as an antenna to sensitize core/shell UCNCs. The dye can increase absorptivity and broaden the absorption spectrum of the UCNCs. Such dye sensitization, in combination with a core/shell structure, can tremendously enhance the upconversion luminescence (UCL) intensity of the UCNCs. The UCL intensity of dye-sensitized UCNCs excited at 820 nm is 800-folds higher than that of pure UCNCs excited at 980 nm. Further enhancement can be obtained by optimization of the dye emission and UCNC absorption spectral overlap. Moreover, the proposed approach can be extended to cover any part of the solar spectrum by using a set of dyes. This work provides new insights into the efficient enhancement of upconversion luminescence of the UCNCs and facilitates their applications.

A simple and effective route has been developed to synthesize a three-dimensional (3D) Mn3O4 hierarchical architecture, which shows a flower-like morphology and is composed of Mn3O4 nanosheets. Two experimental parameters, hydrothermal temperature and NaOH addition speed, were revealed to have critical effects on the formation of the morphology. Furthermore, these Mn3O4 materials were successfully applied to degrade the organic pollutants in water. Compared with Mn3O4 nanoparticles and nanorods, 3D flower-like Mn3O4 nanostructures are found to most heavily enhance the MB degradation efficiency of the UV/H2O2 advanced oxidation process (AOP), which comes from their high BET surface area and good absorption ability.

To date, considerable effort has been devoted to determine the potential toxicity of nanoparticles to cells and organisms. However, determining the mechanism of cytotoxicity induced by different types of nanoparticles remains challenging. Herein, typically low toxicity nanomaterials were used as a model to investigate the mechanism of cytotoxicity induced by low toxicity nanomaterials. We studied the effect of nano-TiO2, nano-Al2O3 and nano-SiO2 deposition films on the ion concentration on a cell-free system simulating the cell membrane. The results showed that the ion concentration of K+, Ca2+, Na+, Mg2+ and SO42− decreased significantly following filtration of the prepared deposition films. More specifically, at a high nano-TiO2 concentration (200 mg L−1) and a long nano-TiO2 deposition time (48 h), the concentration of Na+ decreased from 2958.01 to 2775.72, 2749.86, 2757.36, and 2719.82 mg L−1, respectively, for the four types of nano-TiO2 studied. Likewise, the concentration of SO42− decreased from 38.83 to 35.00, 35.80, 35.40, and 35.27 mg L−1, respectively. The other two kinds of typical low toxicity nanomaterials (nano-Al2O3 and nano-SiO2) have a similar impact on the ion concentration change trend. Adsorption of ions on nanoparticles and the hydrated shell around the ions strongly hindered the ions through the nanoparticle films. The endocytosed nanoparticles could be released from the cells without inducing cytotoxicity. Hindering the ion exchange and disrupting the exocytosis process are the main factors that induce cytotoxicity in the presence of excess nano-TiO2 on the cell surface. The current findings may offer a universal principle for understanding the mechanism of cytotoxicity induced by low toxicity nanomaterials.

Applicable surface enhanced Raman scattering (SERS) active substrates require high enhancement factor (EF), excellent spatial reproducibility, and low-cost fabrication method on a large area. Although several SERS substrates with high EF and relative standard deviation (RSD) of signal less than 5% were reported, reliable fabrication for large area SERS substrates with both high sensitivity and high reproducibility via low-cost routes remains a challenge. Here, we report a facile and cost-effective fabrication process for large-scale SERS substrate with Ag inter-nanoparticle (NP) gaps of 5 nm based on ultrathin alumina mask (UTAM) surface pattern technique. Such closely packed Ag NP arrays with high density of electromagnetic field enhancement (“hot spots”) on large area exhibit high SERS activity and excellent reproducibility, simultaneously. Rhodamine 6G molecules with concentration of 1 × 10–7 M are used to determine the SERS performance, and an EF of ∼109 is obtained. It should be noted that we obtain RSDs about 2% from 10 random spots on an area of 1 cm2, which implies the highly reproducible signals. Finite-difference time-domain simulations further suggest that the enhanced electric field originates from the narrow gap, which agrees well with the experimental results. The low value of RSD and the high EF of SERS signals indicate that the as-prepared substrate may be promising for highly sensitive and uniform SERS detection.Keywords: Ag nanoparticles; high reproducibility; nanogaps of 5 nm; SERS; ultrathin alumina mask technique;

•Highly reduced and ordered TiO2 nanotube arrays have been fabricated using two-step anodization and three-electrode reduction.•The reduced TiO2 nanotube arrays show a high specific capacitance of 24.07 mF cm-2 at a scan rate of 10 mV s-1, which is 1094 times higher than the capacitance of pristine nanotube arrays (0.02 mF cm-2).•They also show an excellent long-term cycling stability with only 1.9% reduction of capacitance after 2000 cycles.•Under optimized reduction conditions, about 22% of Ti4+ ions in tube surface regions are converted into Ti3+ ions.•A proton-electron coupled reduction mechanism has been proposed based on the combined paradigms of a conventional energy-band model and chemical evolution of basic building blocks of TiO2.Highly reduced and ordered TiO2 nanotube arrays have been fabricated using two-step anodization and three-electrode reduction. A proton-electron coupled reduction mechanism has been proposed based on the combined paradigms of a conventional energy-band model and chemical evolution of basic building blocks of TiO2. Under optimized reduction conditions, about 22% of Ti4+ ions in tube surface regions are converted into Ti3+ ions while the morphology of the highly reduced TiO2 nanotube arrays keeps unchanged. The reduced nanotube arrays show superior electrochemical properties such as high areal capacitance, good rate capability, and high cycling stability. The areal capacitance of the reduced electrode is 24.07 mF cm−2 at a scan rate of 10 mV s−1, much higher than that of the pristine TiO2 nanotube arrays (0.02 mF cm−2). This kind of highly reduced one-dimensional oxide nanostructures can find a large array of applications in supercapacitors, photocatalysis, electrochromic display, and Li ion batteries.

A large-area cost-effective Ni/Au hybrid nanoparticle array is synthesized with a proposed versatile and simple process by depositing Au on the pre-prepared arrays of Ni particles with ultra-thin alumina membranes as shadow mask during the deposition. A highly efficient and stable surface enhancement Raman scattering (SERS) substrate could be obtained from utilizing the resulting regular pattern of Ni/Au NP arrays. As compared with the single Au NP arrays, a largely decreased Au evaporation thickness and much lesser Au is needed for achieving the same Raman enhancement factor for the Ni/Au NP arrays. Subsequent SERS spectra measurement of the crystal violet (CV) molecule detection indicate a good SERS-active sensitivity with a detection limit of 10−10 M concentration, a large Raman enhancement factor at 108 was obtained, excellent SERS signal reproducibility with a relative standard deviation (RSD) as low as 6–7% as well as a great long term stability at 10 months.

Microcystin-LR (MC-LR), a problematic potent cyanotoxin, is produced by a variety of cyanobacteria. The presence of MC-LR in drinking water is a severe threat to human health as well as an environmental concern. The control of these algal blooms and their associated toxins is critical for ensuring safe drinking water to significant populations. To the best of our knowledge, this is the first detailed study about the application of Electron Beam Irradiation (EBI) for the control of Microcystis aeruginosa algae cultures and simultaneous degradation of MC-LR. The effects of EBI dose on MC production and removal efficiency were investigated by measuring intercellular and extracellular MC concentrations. The dramatic decreases in MC concentration in the cells and solution were observed under our experimental conditions. The correlation between Chl-a and MC concentrations is eliminated. The inhibition of cell growth and degradation of MC-LR by EBI is highly efficient during radiolysis.

A novel double-shell-structured β-NaLuF4:Gd,Yb,Tm@SiO2@TiO2:Mo nanocomposite photocatalyst has been developed for the first time. The nanocomposite consists of uniform β-NaLuF4:Gd,Yb,Tm upconversion nanocrystals as the core, a media shell of SiO2, and a lot of small sized anatase TiO2 nanoparticles as the outer shell. The TiO2 shell is modified by Mo-doping, which can narrow the band-gap of TiO2 and act as an electron trap, resulting in enhancement of light absorption and reduction of the recombination rate of the photogenerated carriers. The upconversion nanocrystals can convert NIR into UV and visible light which is overall absorbed by the modified TiO2 shell. The photocatalytic activities of the prepared products are evaluated through photocatalytic degradation of RhB under the irradiation of simulated solar and NIR light. The results show that the as-prepared nanocomposite displays a high photocatalytic activity which is significantly higher than that of commercial P25 and pure TiO2. This work provides new insights into the fabrication of TiO2-based composites as high performance photocatalysts and facilitates their application in environmental protection issues using solar light.

Concentrations of hexabromocyclododecanes (HBCDs) were determined in surface sediments of Shanghai, China. The concentrations of total HBCD diastereoisomers (ΣHBCD) ranged from 0.01 to 13.70 ng g−1 dry weight (dw) with a mean value of 3.41 ng g−1 dw, which was up to several orders of magnitude lower than those reported for sediments from European countries. The ΣHBCD concentrations in sediments from chemical/textile industrial or densely populated areas were generally higher than those from rural or less chemical/textile industrialized areas in Shanghai. A high proportion of α-HBCD was observed in sediment samples and was significantly higher than that of commercial HBCD products. This might be due to thermal isomerization from γ-HBCD to α-HBCD and slower degradation rate of α-HBCD compared to γ-HBCD in anaerobic conditions. The mass inventory of ΣHBCD in surface sediments of Shanghai was estimated at 164.4 kg, representing a significant source of HBCDs to the Shanghai environment. This indicates that further study on potential transfer of HBCDs from sediments to aquatic organisms and ecological risk assessments is required.

At present, safety evaluation standards for nanofood additives are made based on the toxic effects of a single additive. Since the size, surface properties and chemical nature influence the toxicity of nanomaterials, the toxicity may have dramatically changed when nanomaterials are used as food additives in a complex system. Herein, we investigated the combined toxicity of zinc oxide nanoparticles (ZnO NPs) and vitamin C (Vc, ascorbic acid). The results showed that Vc increased the cytotoxicity significantly compared with that of the ZnO only NPs. When the cells were exposed to ZnO NPs at a concentration less than 15 mg L−1, or to Vc at a concentration less than 300 mg L−1, there was no significant cytotoxicity, both in the case of gastric epithelial cell line (GES-1) and neural stem cells (NSCs). However, when 15 mg L−1 of ZnO NPs and 300 mg L−1 of Vc were introduced to cells together, the cell viability decreased sharply indicating significant cytotoxicity. Moreover, the significant increase in toxicity was also shown in the in vivo experiments. The dose of the ZnO NPs and Vc used in the in vivo study was calculated according to the state of food and nutrition enhancer standard. After repeated oral exposure to ZnO NPs plus Vc, the injury of the liver and kidneys in mice has been indicated by the change of these indices. These findings demonstrate that the synergistic toxicity presented in a complex system is essential for the toxicological evaluation and safety assessment of nanofood.

We report the fabrication of long titanium dioxide nanotube arrays with highly c-axis preferentially oriented crystallization and a high concentration of oxygen vacancies by second anodization in ethylene glycol and annealing under poor-oxygen conditions. By optimizing the growth and annealing conditions, the [001] oriented crystallization is maximized, and 31.7% of the total Ti ions exists as Ti3+ ions. The carrier density of the [001]-oriented TiO2 nanotube arrays is two orders of magnitude higher than that of the randomly oriented TiO2 nanotube arrays. The unusual c-textured crystallization confined within nanotubes may involve the formation of TiO62− octahedra with a gradient distribution along the tube axis, preferential nucleation at the top, and preferential growth downwards along the c axis. Because of the c-axis preferential orientation and a high-concentration of oxygen vacancies, long TiO2 nanotube arrays can serve as superior electrodes for both lithium ion batteries and supercapacitors without the addition of any conductive agents. Long c-oriented TiO2 nanotube arrays deliver reversible capacities of 293 mA h g−1 at 0.5 C and 174 mA h g−1 at 5 C with Coulombic efficiencies of over 99%, and hold an areal capacitance of 8.21 mF cm−2 with an 85% capacitance retention after 5000 cycles. Double roles played by oxygen vacancies are identified in increasing electrical conductivity and activating the rich-Li phase.

Upconversion nanocrystals have many advantages over other fluorescent materials. However, their upconversion luminescence intensities are not desirable, limiting their applications for highly sensitive detection. Therefore, it is really important to enhance upconversion luminescent intensities of upconversion nanocrystals. In the present study, a novel Ag core and upconversion nanocrystal shell based nanocomposite Ag@SiO2@Lu2O3:Gd/Yb/Er for metal-enhanced upconversion luminescence was fabricated successfully, and its morphology, crystalline phase, composition, optical property, and cell imaging application were investigated. It was found that a maximum upconversion luminescence enhancement of 30-fold was obtained in comparison with the control without a silver core, and the nanocomposite exhibited bright upconversion luminescence when it was used for imaging with HeLa cells. This enhancement potentially increases the overall upconversion nanocrystal detectability, endowing the nanocomposite with a potential capability for highly sensitive biological, medical, and optical detection.Keywords: cell imaging; core−shell structure; enhancement upconversion luminescence; nanocomposite Ag@SiO2@Lu2O3:Gd/Yb/Er; synthesis

Zinc oxide nanoparticles (ZnO NPs) are widely used as food additives, especially in nutritional foods. However, many reports have demonstrated their toxicity in humans and other biological systems. Our study has confirmed that ZnO NPs can induce apoptosis and oxidative damage on human gastric epithelium cells (GES-1). Caseinophosphopeptides (CPP) are also used as functional food additives that sequester prooxidant metals and scavenge free radicals. Herein, we investigate the combined cytotoxicity of ZnO NPs and CPP for the first time. The results show that CPP protects GES-1 cells from oxidative stress induced by ZnO NPs, decreases reactive oxygen species, diminishes the level of malondialdehyde, increases the content of glutathione and improves the activity of superoxide dismutase. Therefore, CPP can protect GES-1 cells against ZnO NP induced injury through the down-regulation of oxidative stress.

Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) have been reported to be formed during incineration processes. Despite dioxin-like toxicities of ClPAHs, little is known on the occurrence of these chemicals in the environment. In this study, concentrations of 24-h airborne PM10 and PM2.5-associated ClPAHs and their corresponding parent PAHs were monitored from October 2011 to March 2012 in a suburban area in Shanghai, China. In addition, daytime and nighttime particle samples were collected for 7 days in April from the same sampling site. Twelve of twenty ClPAH congeners were found in PM10 and PM2.5 at concentrations ranging from 2.45 to 47.7 pg/m3 with an average value of 12.3 pg/m3 for PM10, and from 1.34 to 22.3 pg/m3 with an average value of 9.06 pg/m3 for PM2.5. Our results indicate that ClPAHs are ubiquitous in inhalable fine particles. The concentrations of ∑ClPAHs and specific congeners such as 9-ClPhe, 3-ClFlu, 1-ClPyr, 7-ClBaA, and 6-ClBaP in particles collected during nighttime were higher than those collected during daytime, which suggests not only diffusion of ClPAHs in air by atmospheric mixing but also photochemical degradation during daylight hours. Among the individual ClPAHs determined, 6-ClBaP, 1-ClPyr, and 9-ClPhe were the dominant compounds in PM10 and PM2.5. The percent composition of 6-ClBaP, 1-ClPyr, 7-ClBaA, and 3-ClFlu between PM10 and PM2.5 was similar. Significant positive correlations were found between concentrations of ClPAHs and their corresponding parent PAHs, particle mass, and total organic carbon (organic carbon plus elemental carbon), indicating that ClPAHs are sorbed onto carbonaceous matter of PM. Concentrations of parent PAHs predicted by multiple linear regression models with PM mass, total organic carbon, temperature, and relative humidity as variables reflected the measured concentrations with a strong coefficient of determination of 0.917 and 0.946 for PM10 and PM2.5, respectively. However, the models generated to predict ClPAH concentrations in PM did not yield satisfactory results, which suggested the differences in physical–chemical properties and formation processes between ClPAHs and their corresponding parent PAHs. 7-ClBaA and 6-ClBaP collectively accounted for the preponderance of the total dioxin-like TEQ concentrations of ClPAHs (TEQClPAH) in PM samples. Exposure to toxic compounds such as ClPAHs and PAHs present in PM2.5 can be related to adverse health outcomes in people.

Eight Polybrominated diphenyl ether (PBDE) congeners (BDE 28, 47, 99, 100, 153, 154, 183 and 209) were determined to examine the hair burden at low concentrations, and the relationship between PBDE concentrations in human hair and indoor dust from a college environment (Shanghai University campus). Chemical analyses showed that the total concentrations of PBDEs in hair ranged from 4.04 to 99 ng/g dw, and were found to be fourfold higher in females than in males (p < 0.05). The total PBDEs concentrations in indoor dust samples ranged from 170 to 1,360 ng/g dw. Significantly positive correlations were observed between human hair and indoor dust for BDE 47 (r = 0.44, p = 0.048) and BDE 99 (r = 0.68, p = 0.025). However, no significant association was noted between other PBDE congeners in human hair and indoor dust in the present study.

TiO2 nanotubes (TiO2-NTs) are currently attracting a high interest because the intrinsic properties of TiO2 provide the basis for many outstanding functional features. Herein, we focus on the cytotoxicity and sublocation of TiO2-NTs in neural stem cells (NSCs). The cytotoxicity of TiO2-NTs is investigated using the methyl tetrazolium cytotoxicity and reactive oxygen species assay, the apoptosis assay by flow cytometry. Cell viability assay shows that TiO2-NTs inside cells are nontoxic at the low concentration. A time-dependent relationship is observed, while a dose-dependent relationship is seen only at the concentration higher than 150 μg/ml. The uptake happens shortly after incubation with cells. TiO2-NTs can easily pass through the cell membrane and enter into the cells. The uptake amount is increased with prolonging incubation time and reach to maximum at 48 h. Transmission electron microscopy and confocal is used to study subcellular location of TiO2-NTs. It is found that TiO2-NTs traversed cell membrane and localized in many vesicles (endosomes and lysosomes) and cytoplasm. TiO2-NTs in NSCs firstly disperse or metabolism by lysosomal enzymes and then exocytosis from NSCs.

In this paper, porous hollow silica nanoparticles (HSNS) have been successfully fabricated by a novel combination of stabilizing condensation and dynamic self-assembly. In composition, porous silica nanoparticles (MSNS-1, MSNS-2) and porous silica nanocapsules (SNC) were successfully synthesized. The silica nanostructures were characterized by small-angle X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption measurements. HSNS have higher specific surface areas and large pore volumes than MSNS and SNC. The formation mechanism of the silica nanostructures was discussed. Further, encapsulation of organic molecules into HSNS and their controlled release were investigated by using Doxorubicin (DOX) as a model. HSNS show excellent drug delivery properties. DOX-loaded silica nanostructures exhibit superb drug release behavior, which is controlled by varying the pH. The current approaches will doubtlessly open many possibilities toward biological and technological applications of silica nanomaterials.Graphical abstractIn order to control the drug release, porous hollow silica nanoparticles (HSNS) have been successfully fabricated by a novel combination of stabilizing condensation and dynamic self-assembly. In composition, porous silica nanoparticles (MSNS-1, MSNS-2) and porous silica nanocapsules (SNC) were successfully synthesized. In situ encapsulation of organic molecules into HSNs and their controlled release were further investigated by using Doxorubicin (Dox) as a typical example. DOX-loaded silica nanostructures exhibit superb drug release behavior and can be controlled by varying the pH.Research highlights► Porous hollow silica nanoparticles have been fabricated by a novel combination. ► Encapsulation of drug and their controlled release were investigated. ► HSNS show excellently drug delivery properties. ► Drug release can be controlled by varying the pH.

In this paper, the TiO2 nanotubes were synthesized by hydrothermal method using a 10 mol/L NaOH aqueous solution at 150 °C. The structure of prepared materials was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and Brunauer–Emmett–Teller (BET). The prepared TiO2 nanotubes were used to prepare thick film gas sensors and the gas sensing properties to various gases were tested. Results show the prepared TiO2 nanotube gas sensors responses to ethanol under dry condition at 450 °C. This could be attributed to the fact that it had high porous morphology and a higher pore volume, which can promote the diffusion of ethanol deep inside the films and improve the sensor response. Moreover, the gas sensor made with nanotubes exhibit high selective response towards ethanol gas compared with H2, CO, acetone.

This paper reports the microwave-assisted synthesis of Co3O4 nanomaterials with different morphologies including nanoparticles, rod-like nanoclusters and macroporous platelets. The new macroporous platelet-like Co3O4 morphology was found to be the best suitable for reversible lithium storage properties. It displayed superior cycling performances than nanoparticles and rod-like nanoclusters. More interestingly, excellent high rate capabilities (811 mAh g−1 at 1780 mA g−1 and 746 mAh g−1 at 4450 mA g−1) were observed for macroporous Co3O4 platelet. The good electrochemical performance could be attributed to the unique macroporous platelet structure of Co3O4 materials.

This paper reports a facile solution route (water bath heating or hydrothermal heating) for synthesizing a few Sb-based self-assembly structures including bundles of nanowires, nanowire-flowers, long nanowires, bundles of flakes, nanobelts, hollow prisms. These obtained nanomaterials were characterized by XRD, FE-SEM, TEM, SAED, and HRTEM. It was found that the morphology, size and phase of self-assembly nanostructures were strongly dependent on reaction temperature, reaction time, pH value, and heating source. In particular, nanowire-flowers and hollow prisms of antimony oxide or oxychloride have not been reported previously. A possible mechanism based on stepwise nucleation and aggregation of nanowires or flakes was also proposed.

Upconversion nanocrystals (UCNCs) hold promise for bioimaging, solar cells, photocatalysis and volumetric displays. However, their upconversion luminescence intensities are usually low due to the weak and narrowband near-infrared absorption of lanthanide ions. Herein, we introduce and validate a strategy to hugely enhance upconversion luminescence intensity by using an organic near-infrared dye as an antenna to sensitize core/shell UCNCs. The dye can increase absorptivity and broaden the absorption spectrum of the UCNCs. Such dye sensitization, in combination with a core/shell structure, can tremendously enhance the upconversion luminescence (UCL) intensity of the UCNCs. The UCL intensity of dye-sensitized UCNCs excited at 820 nm is 800-folds higher than that of pure UCNCs excited at 980 nm. Further enhancement can be obtained by optimization of the dye emission and UCNC absorption spectral overlap. Moreover, the proposed approach can be extended to cover any part of the solar spectrum by using a set of dyes. This work provides new insights into the efficient enhancement of upconversion luminescence of the UCNCs and facilitates their applications.

A simple and effective route has been developed to synthesize a three-dimensional (3D) Mn3O4 hierarchical architecture, which shows a flower-like morphology and is composed of Mn3O4 nanosheets. Two experimental parameters, hydrothermal temperature and NaOH addition speed, were revealed to have critical effects on the formation of the morphology. Furthermore, these Mn3O4 materials were successfully applied to degrade the organic pollutants in water. Compared with Mn3O4 nanoparticles and nanorods, 3D flower-like Mn3O4 nanostructures are found to most heavily enhance the MB degradation efficiency of the UV/H2O2 advanced oxidation process (AOP), which comes from their high BET surface area and good absorption ability.

We report the fabrication of long titanium dioxide nanotube arrays with highly c-axis preferentially oriented crystallization and a high concentration of oxygen vacancies by second anodization in ethylene glycol and annealing under poor-oxygen conditions. By optimizing the growth and annealing conditions, the [001] oriented crystallization is maximized, and 31.7% of the total Ti ions exists as Ti3+ ions. The carrier density of the [001]-oriented TiO2 nanotube arrays is two orders of magnitude higher than that of the randomly oriented TiO2 nanotube arrays. The unusual c-textured crystallization confined within nanotubes may involve the formation of TiO62− octahedra with a gradient distribution along the tube axis, preferential nucleation at the top, and preferential growth downwards along the c axis. Because of the c-axis preferential orientation and a high-concentration of oxygen vacancies, long TiO2 nanotube arrays can serve as superior electrodes for both lithium ion batteries and supercapacitors without the addition of any conductive agents. Long c-oriented TiO2 nanotube arrays deliver reversible capacities of 293 mA h g−1 at 0.5 C and 174 mA h g−1 at 5 C with Coulombic efficiencies of over 99%, and hold an areal capacitance of 8.21 mF cm−2 with an 85% capacitance retention after 5000 cycles. Double roles played by oxygen vacancies are identified in increasing electrical conductivity and activating the rich-Li phase.