Activity enhancement of layered cobalt hydroxide nanocones by tuning interlayer spacing and phosphidation for electrocatalytic water oxidation in neutral solutions

We explored the electrocatalytic performance of cobalt hydroxide nanocones in neutral solutions via tuning the interlayer spacing and phosphidation.

In situ growth of metallic Ag0 intercalated CoAl layered double hydroxides as efficient electrocatalysts for the oxygen reduction reaction in alkaline solutions

Metallic Ag⁰ intercalated CoAl LDHs synthesized via a facile redox process exhibited excellent ORR activity through a four-electron reduction process.

Developing a Bright NIR-II Fluorophore with Fast Renal Excretion and Its Application in Molecular Imaging of Immune Checkpoint PD-L1

Fluorescence imaging in the second near-infrared (NIR-II) window holds impressive advantages of enhanced penetration depth and improved signal-to-noise ratio. Bright NIR-II fluorophores with renal excretion ability and low tissue accumulation are favorable for in vivo molecular imaging applications as they can render the target-mediated molecular imaging process easily distinguishable. Here, a probe (anti-PD-L1-BGP6) comprising a fluorophore (IR-BGP6) covalently bonded to the programmed cell death ligand-1 monoclonal antibody (PD-L1 mAb) for molecular imaging of immune checkpoint PD-L1 (a targeting site upregulated in various tumors for cancer imaging) in the NIR-II window is reported. Through molecular optimization, the bright NIR-II fluorophore IR-BGP6 with fast renal excretion (≈91% excretion in general through urine within the first 10 h postinjection) is developed. The conjugate anti-PD-L1-BGP6 succeeds in profiling PD-L1 expression and realizes efficient noninvasive molecular imaging in vivo, achieving a tumor to normal tissue (T/NT) signal ratio as high as ≈9.5. Compared with the NIR-II fluorophore with high nonspecific tissue accumulation, IR-BGP6 derived PD-L1 imaging significantly enhances the molecular imaging performance, serving as a strong tool for potentially studying underlying mechanism of immunotherapy. The work provides rationales to design renal-excreted NIR-II fluorophores and illustrate their advantages for in vivo molecular imaging.

Isotopic composition of atmospheric precipitation and its tracing significance in the Laohequ Basin, Loess plateau, China

Based on the δ¹⁸O and δD values in precipitation and related meteorological parameters in the Chinese Loess Plateau (CLP) from June 2014 to April 2016, the effects of temperature and precipitation amount effect on stable isotopic compositions were analyzed, as well as the tracing significance of deuterium excess. The results show that the Local Meteoric Water Line (LMWL) was defined as δD = 7.08δ¹⁸O + 4.73(R² = 0.99), with a slope of <8, indicating that a non-equilibrium evaporation process occurred when the drops fell below the cloud base in the arid and semi-arid environment. The temperature effect was defined as δD = 0.4536T-46.937.44 (r = 0.113, n = 150, p = 0.168), which shows a weak positive correlation between temperature and isotopic composition. Meanwhile, the precipitation amount effect was defined as δD = -0.7883P-34.152 (r = -0.223, n = 150, p = 0.011), which shows a weak negative correlation between temperature and isotope composition. The slopes in cross plotting δD - δ¹⁸O records were 8.3, 7.7, 7.4, and 6.3, displaying a decreasing trend in the temperature gradient of T ≤ 0 °C, 0 < T ≤ 10 °C, 10 < T ≤ 20 °C and T > 20 °C, respectively. The amount effect is significant (δD = -7.0946P + 48.686, r = -0.548, n = 20, p = 0.012) in the precipitation range from 10 to 20 mm. The average deuterium excess values in winter were 24‰ and 25.3‰ for 2015 and 2016, respectively; however, the low values of 3.1‰ and 5.5‰ occurred in the summers of 2014 and 2015, respectively. These results suggested that intense sub-cloud evaporation decreased the deuterium excess values in the Chinese Loess Plateau under the climate conditions of the rainy season with high temperatures. However, deuterium excess values of snow in wintertime (LT-1, LT-2) could be reflective of the reliable characteristics of atmospheric vapor for weak sub-cloud evaporation and surface evaporation.

A surface transition of nanoparticle-decorated graphene films from water-adhesive to water-repellent

Herein, a facile strategy is introduced to realize the transition of graphene films from a water-adhesion surface (adhesive pressure of 541.5 Pa) to a water-repellent surface (adhesive pressure of ∼0 Pa) via decoration of carbon nanoparticles. Cassie impregnating wetting state and Cassie state are used to explain highly adhesive effect and strong repelling effect, respectively. Droplet impacting experiments demonstrate that the as-prepared graphene films have a stable structure, which is beneficial for their applications.

Confounding effect of benign pulmonary diseases in selecting volatile organic compounds as markers of lung cancer

Lung cancer (LC) is a leading cause of cancer-related morbidity and mortality globally, and exhaled breath testing has been considered as a fast, convenient and non-invasive way to diagnose LC in its early stages. Volatile organic compounds (VOCs), as markers of LC in exhaled breath, have been widely investigated for cancer diagnosis. However, few studies have reported on the interference of benign pulmonary diseases (BPD) in the selection of VOC markers for LC. During this study, 207 samples were analyzed using thermal desorption instrumentation/gas chromatography/mass spectrometry (TD-GCMS) to detect C₆-C₃₀ VOCs, and all samples were divided into four groups: LC group, BPD group, lung disease (LD) group (including LC group and BPD group) and healthy group. To make up for the deficiency of detecting low carbon hydrocarbons (<C₆), 277 samples were analyzed using solid-phase micro-extraction/gas chromatography/mass spectrometry (SPME-GCMS), divided among the four groups. VOC markers were selected by reference to the receiver operating characteristics curve. With the comparisons among the LC group, BPD group and healthy group from TD-GCMS and SPME-GCMS results, we found that exhaled VOCs are capable of discriminating LC group versus healthy group and BPD group versus healthy group with a consistency of 70%-80%. However, no VOCs can be selected with good discrimination capability between the LC group and BPD group, indicating that BPD interferes significantly in VOC marker selection for LC. To discriminate breath samples from the LD group and healthy group, 11 VOCs, including ten selected from TD-GCMS and one from SPME-GCMS, were chosen as markers for LD diagnosis. The sensitivity, specificity and overall accuracy of the diagnostic model established using ten VOCs were 80.8%, 84% and 82.7%, and those of the model established by using one VOC were 75.6%, 78.9% and 76.7%. These results validate that LD patients can be effectively discriminated and diagnosed using exhaled VOC analysis. (Clinical trial registration number: ChiCTR-DCD-15007106.).

Graphene FET Array Biosensor Based on ssDNA Aptamer for Ultrasensitive Hg2+ Detection in Environmental Pollutants

Invisible mercury ion is an extremely poisonous environmental pollutant, therefore, a fast and highly sensitive detection method is of significant importance. In this study, a liquid-gated graphene field-effect transistor (GFET) array biosensor (6 × 6 GFETs on the chip) was fabricated and applied for Hg²⁺ quantitate detection based on single-stranded DNA (ssDNA) aptamer. The biosensor showed outstanding selectivity to Hg²⁺ in mixed solutions containing various metal ions. Moreover, the sensing capability of the biosensor was demonstrated by real-time responses and showed a fairly low detection limit of 40 pM, a wide detection ranged from 100 pM to 100 nM and rapid response time below one second. These results suggest that the GFET array biosensor based on ssDNA aptamer offers a simple fabrication procedure and quite fast method for mercury ion contaminant detection and are promising for various analytical applications.

Role of von Willebrand factor and ADAMTS-13 in early brain injury after experimental subarachnoid hemorrhage

Essentials von Willebrand Factor (VWF) and ADAMTS13 may affect early injury after subarachnoid hemorrhage (SAH). Early brain injury was assessed in VWF-/- , ADAMTS13-/- and recombinant (r) ADAMTS13 treated mice. VWF-/- and rADAMTS13 treated mice had less brain injury than ADAMTS13-/- and wild-type mice. Early administration of rADAMTS13 may improve outcome after SAH by reducing early brain injury.

SUMMARY

Background Early brain injury is an important determinant of poor functional outcome and case fatality after aneurysmal subarachnoid hemorrhage (SAH), and is associated with early platelet aggregation. No treatment exists for early brain injury after SAH. We investigated whether von Willebrand factor (VWF) is involved in the pathogenesis of early brain injury, and whether ultra-early treatment with recombinant ADAMTS-13 (rADAMTS-13) reduces early brain injury after experimental SAH. Methods Experimental SAH in mice was induced by prechiasmatic injection of non-anticoagulated blood from a littermate. The following experimental SAH groups were investigated: C57BL/6J control (n = 21), VWF-/- (n = 25), ADAMTS-13-/- (n = 23), and C57BL/6J treated with rADAMTS-13 (n = 26). Mice were killed at 2 h after SAH. Primary outcome measures were microglial activation (IBA-1 surface area) and neuronal injury (number of cleaved caspase-3-positive neurons). Results As compared with controls, microglial activation was decreased in VWF-/- mice (mean difference of - 20.0%, 95% confidence interval [CI] - 4.0% to - 38.6%), increased in ADAMTS-13-/- mice (mean difference of + 34.0%, 95% CI 16.2-51.7%), and decreased in rADAMTS-13-treated mice (mean difference of - 22.1%, 95% CI - 3.4% to - 39.1%). As compared with controls (185 neurons, interquartile range [IQR] 133-353), neuronal injury in the cerebral cortex was decreased in VWF-/- mice (63 neurons, IQR 25-78), not changed in ADAMTS-13-/- mice (53 neurons, IQR 26-221), and reduced in rADAMTS-13-treated mice (45 neurons, IQR 9-115). Conclusions Our findings suggest that VWF is involved in the pathogenesis of early brain injury, and support the further study of rADAMTS-13 as a treatment option for early brain injury after SAH.

Two-dimensional porous cuprous oxide nanoplatelets derived from metal-organic frameworks (MOFs) for efficient photocatalytic dye degradation under visible light

Bottom-up synthesis is a promising method to design and control the morphology of metal-organic frameworks (MOFs). Here, square shaped two-dimensional (2D) MOF nanoplatelets with a thickness of ∼80 nm and a lateral dimension of 4-6 μm were successfully synthesized through a facile solvothermal treatment of Cu(NO3)2 and 4,4'-bipyridine in the presence of polyvinyl pyrrolidone (PVP). The growth of a cross-weaved structure assembled via 1D chains linked with 4,4'-bipyridine along the layer stacking direction was hindered by PVP, resulting in a high-aspect ratio of the nanoplatelets. Subsequent annealing treatment converted the Cu-based MOFs into porous N-doped Cu2O/carbon composites, retaining the 2D square morphology. This annealed product showed a higher performance in the degradation of methyl orange under visible light compared to previously reported Cu2O composites. By using a small amount of the catalyst, the degradation rate could reach up to 2.5 mg min-1 gcat-1 as a result of the efficient absorption of visible light and high surface area of the porous catalysts.

Three-dimensionally interconnected Si frameworks derived from natural halloysite clay: a high-capacity anode material for lithium-ion batteries

On account of its high theoretical capacity, silicon (Si) has been regarded as a promising anode material for Li-ion batteries. Extracting Si content from earth-abundant and low-cost aluminosilicate minerals, rather than from artificial silica (SiO2) precursors, is a more favorable and practical method for the large-scale application of Si anodes. In this work, three-dimensionally interconnected (3D-interconnected) Si frameworks with a branch diameter of ∼15 nm are prepared by the reduction of amorphous SiO2 nanotubes derived from natural halloysite clay. Benefiting from their nanostructure, the as-prepared 3D-interconnected Si frameworks yield high reversible capacities of 2.54 A h g-1 at 0.1 A g-1 after 50 cycles, 1.87 A h g-1 at 0.5 A g-1 after 200 cycles, and 0.97 A h g-1 at 2 A g-1 after a long-term charge-discharge process of 500 cycles, remarkably outperforming the commercial Si material. Further, when the as-prepared Si frameworks and commercial LiCoO2 cathodes are paired in full cells, a high anode capacity of 0.98 A h g-1 is achieved after 100 cycles of rapid charge/discharge at 2 A g-1. This work provides a new strategy for the synthesis of high-capacity Si anodes derived from natural aluminosilicate clay.

Electron donor and acceptor functionalized dithienylethenes: effects of charge density on photochromic properties

Electron-donating triphenylamine and/or electron-withdrawing pyromellitic diimide (PMDI) are functionalized on dithienylethene (DTE) and three novel photochromic materials have been designed and successfully synthesized. All the compounds display reversible photochromism due to the molecular switching between ring-closed isomers upon UV light irradiation and ring-open isomers upon exposure to visible light. Thus they can be applied as an anti-counterfeiting ink. Moreover, the study of the photoswitching kinetics reveals that both the ring-closing and ring-opening reactions are first-order reactions. Further charge population analysis discovers that the electron densities of the substituents at the DTE core have a dramatic influence on the photochromic properties. The incorporation of electron-donating triphenylamine groups at the α-position of the thiophene rings in the DTE unit facilitates the ring-closing reaction upon UV light irradiation. In contrast, the substitution of an electron-withdrawing PMDI unit in the DTE unit is beneficial to the ring-opening reaction upon irradiation of visible light. This work may help to understand the photochromism of DTE derivatives and provide a pathway for designing DTE-based photochromes with more or less sensitivity to UV or visible light.

Molecular Cancer Imaging in the Second Near-Infrared Window Using a Renal-Excreted NIR-II Fluorophore-Peptide Probe

In vivo molecular imaging of tumors targeting a specific cancer cell marker is a promising strategy for cancer diagnosis and imaging guided surgery and therapy. While targeted imaging often relies on antibody-modified probes, peptides can afford targeting probes with small sizes, high penetrating ability, and rapid excretion. Recently, in vivo fluorescence imaging in the second near-infrared window (NIR-II, 1000-1700 nm) shows promise in reaching sub-centimeter depth with microscale resolution. Here, a novel peptide (named CP) conjugated NIR-II fluorescent probe is reported for molecular tumor imaging targeting a tumor stem cell biomarker CD133. The click chemistry derived peptide-dye (CP-IRT dye) probe afforded efficient in vivo tumor targeting in mice with a high tumor-to-normal tissue signal ratio (T/NT > 8). Importantly, the CP-IRT probes are rapidly renal excreted (≈87% excretion within 6 h), in stark contrast to accumulation in the liver for typical antibody-dye probes. Further, with NIR-II emitting CP-IRT probes, urethra of mice can be imaged fluorescently for the first time noninvasively through intact tissue. The NIR-II fluorescent, CD133 targeting imaging probes are potentially useful for human use in the clinic for cancer diagnosis and therapy.

A bright organic NIR-II nanofluorophore for three-dimensional imaging into biological tissues

Fluorescence imaging of biological systems in the second near-infrared (NIR-II, 1000-1700 nm) window has shown promise of high spatial resolution, low background, and deep tissue penetration owing to low autofluorescence and suppressed scattering of long wavelength photons. Here we develop a bright organic nanofluorophore (named p-FE) for high-performance biological imaging in the NIR-II window. The bright NIR-II >1100 nm fluorescence emission from p-FE affords non-invasive in vivo tracking of blood flow in mouse brain vessels. Excitingly, p-FE enables one-photon based, three-dimensional (3D) confocal imaging of vasculatures in fixed mouse brain tissue with a layer-by-layer imaging depth up to ~1.3 mm and sub-10 µm high spatial resolution. We also perform in vivo two-color fluorescence imaging in the NIR-II window by utilizing p-FE as a vasculature imaging agent emitting between 1100 and 1300 nm and single-walled carbon nanotubes (CNTs) emitting above 1500 nm to highlight tumors in mice.

3D NIR-II Molecular Imaging Distinguishes Targeted Organs with High-Performance NIR-II Bioconjugates

Greatly reduced scattering in the second near-infrared (NIR-II) region (1000-1700 nm) opens up many new exciting avenues of bioimaging research, yet NIR-II fluorescence imaging is mostly implemented by using nontargeted fluorophores or wide-field imaging setups, limiting the signal-to-background ratio and imaging penetration depth due to poor specific binding and out-of-focus signals. A newly developed high-performance NIR-II bioconjugate enables targeted imaging of a specific organ in the living body with high quality. Combined with a home-built NIR-II confocal set-up, the enhanced imaging technique allows 900 µm-deep 3D organ imaging without tissue clearing techniques. Bioconjugation of two hormones to nonoverlapping NIR-II fluorophores facilitates two-color imaging of different receptors, demonstrating unprecedented multicolor live molecular imaging across the NIR-II window. This deep tissue imaging of specific receptors in live animals allows development of noninvasive molecular imaging of multifarious models of normal and neoplastic organs in vivo, beyond the traditional visible to NIR-I range. The developed NIR-II fluorescence microscopy will become a powerful imaging technique for deep tissue imaging without any physical sectioning or clearing treatment of the tissue.

Rapidly Responsive and Flexible Chiral Nematic Cellulose Nanocrystal Composites as Multifunctional Rewritable Photonic Papers with Eco-Friendly Inks

Rapidly responsive and flexible photonic papers are manufactured by coassembly of cellulose nanocrystals (CNCs) and waterborne polyurethane (WPU) latex for fully taking advantage of the chiral nematic structure of CNCs and the flexibility of WPU elastomer. The resulting CNC/WPU composite papers exhibit not only tunable iridescent colors by adjusting the helical pitch size, but also instant optical responses to water and wet gas, ascribed to the easy chain movement of the elastomeric WPU that does not restrict the fast water absorption-induced swelling of CNCs. By choosing water or NaCl aqueous solutions as inks, the colorful patterns on the CNC/WPU photonic paper can be made temporary, durable, or even disguisable. In addition, the photonic paper is simultaneously rewritable for all these three types of patterns, and the disguisable patterns, which are invisible at normal times and show up under stimuli, exhibit a quick reveal conversion just by exhaling on the paper. The rewritability, rapid responsibility, easy fabrication, and the eco-friendly nature of the inks make the flexible photonic paper/ink combination highly promising in sensors, displays, and photonic circuits.

Miniaturized Planar Room Temperature Ionic Liquid Electrochemical Gas Sensor for Rapid Multiple Gas Pollutants Monitoring

The growing impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand of sensors to monitor hazardous gases. This paper presents a new miniaturized planar electrochemical gas sensor for rapid measurement of multiple gaseous hazards. The gas sensor features a porous polytetrafluoroethylene substrate that enables fast gas diffusion and room temperature ionic liquid as the electrolyte. Metal sputtering was utilized for platinum electrodes fabrication to enhance adhesion between the electrodes and the substrate. Together with carefully selected electrochemical methods, the miniaturized gas sensor is capable of measuring multiple gases including oxygen, methane, ozone and sulfur dioxide that are important to human health and safety. Compared to its manually-assembled Clark-cell predecessor, this sensor provides better sensitivity, linearity and repeatability, as validated for oxygen monitoring. With solid performance, fast response and miniaturized size, this sensor is promising for deployment in wearable devices for real-time point-of-exposure gas pollutant monitoring.

Miniaturized Planar Room Temperature Ionic Liquid Electrochemical Gas Sensor for Rapid Multiple Gas Pollutants Monitoring

The growing impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand of sensors to monitor hazardous gases. This paper presents a new miniaturized planar electrochemical gas sensor for rapid measurement of multiple gaseous hazards. The gas sensor features a porous polytetrafluoroethylene substrate that enables fast gas diffusion and room temperature ionic liquid as the electrolyte. Metal sputtering was utilized for platinum electrodes fabrication to enhance adhesion between the electrodes and the substrate. Together with carefully selected electrochemical methods, the miniaturized gas sensor is capable of measuring multiple gases including oxygen, methane, ozone and sulfur dioxide that are important to human health and safety. Compared to its manually-assembled Clark-cell predecessor, this sensor provides better sensitivity, linearity and repeatability, as validated for oxygen monitoring. With solid performance, fast response and miniaturized size, this sensor is promising for deployment in wearable devices for real-time point-of-exposure gas pollutant monitoring.