Hybrid Nanoparticle/DNAzyme Electrochemical Biosensor for the Detection of Divalent Heavy Metal Ions and Cr3.

A hybrid noble nanoparticle/DNAzyme electrochemical biosensor is proposed for the detection of Pb2+, Cd2+, and Cr3+. The sensor takes advantage of a well-studied material that is known for its selective interaction with heavy metal ions (i.e., DNAzymes), which is combined with metallic nanoparticles. The double-helix structure of DNAzymes is known to dissociate into smaller fragments in the presence of specific heavy metal ions; this results in a measurable change in device resistance due to the collapse of conductive inter-nanoparticle DNAzyme bridging. The paper discusses the effect of DNAzyme anchoring groups (i.e., thiol and amino functionalization groups) on device performance and reports on the successful detection of all three target ions in concentrations that are well below their maximum permitted levels in tap water. While the use of DNAzymes for the detection of lead in particular and, to some extent, cadmium has been studied extensively, this is one of the few reports on the successful detection of chromium (III) via a sensor incorporating DNAzymes. The sensor showed great potential for its future integration in autonomous and remote sensing systems due to its low power characteristics, simple and cost-effective fabrication, and easy automation and measurement.

The interplay between acid-base properties and Fermi level pinning of a nano dispersed tungsten oxide - titania catalytic system.

A series of WO3/TiO2 catalysts were synthesized, characterized, and evaluated for the NO selective catalytic reduction (SCR) with NH3. Based on a wide range of characterization techniques, a detailed model was developed that describes the interfacial electron transfer between WO3 and TiO2 and defines a relationship between the acid-base properties of the catalytic surface and electronic structure modification. The electronic interactions at the WO3/TiO2 interface were quantified using variations in the system's electronic structure. Altering the dispersion and size of the WO3 nanostructures results to drastic changes in titania's surface electron distribution, which are reflected in the pinning of Fermi level through an electron transfer process between WO3 and TiO2. The variations in the Fermi level were further related to changes in the point of zero charge (PZC) values and the activity towards NO SCR with NH3, which was used as a test reaction. Temperature Programmed Surface Reaction (TPSR) was employed to study the catalytic activity at temperatures ranging from 30 °C to 500 °C and was quantitatively correlated to changes in coverage and interfacial charge transfer. We demonstrate that higher WO3 loading on TiO2 results in a stronger electronic interaction and a higher catalytic activity. This is because electron transfer increases the surface electron density, which enhances the surface basicity of TiO2. The concomitant decrease in the adsorption energy of NH3 results in a decrease in the activation energy, which is reflected in the SCR temperature onset.

A multicenter, prospective, observational study of the long-term outcomes of Crohn's disease patients under routine care management in Greece.

BACKGROUND: Real-world data on management patterns and long-term outcomes of patients with inadequately controlled Crohn's disease (CD) in Greece are scarce. METHODS: This was a multicenter, prospective observational study of 18-65-year-old CD patients whose physicians judged that their current therapy was inadequate to control their condition and therefore decided to switch treatment. Data were collected at enrollment (time of switch), and 30, 54 and 104 weeks post-enrollment. RESULTS: Sixty-six eligible patients (median age: 35.8 years; 56.1% males; median CD diagnosis duration: 2.3 years) were enrolled by nine hospital sites. At the time of treatment switch, 66.7% had "mild" (CD activity index [CDAI] <220) and 30.3% "moderate-to-severe" (220≤CDAI≤450) disease activity. Ileocolonic involvement, extraintestinal manifestations, prior CD-related surgeries and prior corticosteroid use were reported in 65.2%, 51.5%, 24.2% and 78.8% of patients, respectively. Throughout the study, most patients were managed with anti-tumor necrosis factor (TNF) medications (74.2%/74.1% infliximab; 10.6%/13.8% adalimumab at enrollment/end of study, respectively). At 54 and 104 weeks post-enrollment, the baseline CDAI score (median 174.5) decreased to 145.5 and 146.0 points (P<0.001) and the baseline C-reactive protein level (median: 13.6 mg/L) decreased to 3.5 and 3.0 mg/L (P<0.001), respectively, not differing statistically between patients with "mild" and "moderate-to-severe" disease activity. In this patient population, 56.1% were corticosteroid-free throughout observation, while for the remaining 43.9%, the mean percentage corticosteroid-free period was 80.2%. CD-related surgeries and hospitalizations were reported in 8.1% and 19.4%, respectively. CONCLUSION: Under routine care in Greece, inadequately controlled CD patients were mainly switched to anti-TNFs, which lowered disease activity and reduced corticosteroid use.

Interfacial oxidation of ultrathin nickel and chromium films on yttria-stabilized zirconia.

The substrate-induced oxidation upon prolonged annealing in UHV of ultrathin films of Ni and Cr vapor deposited on yttria-stabilized zirconia YSZ(100) was studied by X-ray photoelectron spectroscopy (XPS) to obtain information about the oxidation mechanism, determine the available quantity of reactive oxygen in YSZ, and investigate the thermal stability of the thin oxide films. Up to about 0.8 ML of Ni deposited at room temperature was oxidized to NiO at a constant rate at 650 K via the substrate, whereas at slightly higher coverage, the oxidation rate under identical conditions was drastically reduced. In contrast to Ni, up to 4.8 ML of Cr deposited at 275 K could be oxidized via the substrate to Cr2O3 upon extensive UHV annealing at increasing temperature up to 820 K, indicating a reactive oxygen content of at least 4 x 10(-6) with respect to the lattice oxygen in the YSZ specimen. The Cr2O3 decomposed to metallic Cr above about 800 K, whereas NiO was stable up to the maximum temperature of 875 K. These results indicate that the oxidation via the substrate is kinetically analogous to the gas-phase oxidation of bulk Ni and Cr. The reactive oxygen content of the single-crystal YSZ is larger than expected, and part of it is accommodated at the surface of the substrate. The thermal stability of the thin oxide films is determined by the oxygen exchange with YSZ and not by the respective bulk oxide thermodynamic decomposition temperature.