14 research outputs found
The Development of Therapeutic Antibodies That Neutralize Homologous and Heterologous Genotypes of Dengue Virus Type 1
Antibody protection against flaviviruses is associated with the development of neutralizing antibodies against the viral envelope (E) protein. Prior studies with West Nile virus (WNV) identified therapeutic mouse and human monoclonal antibodies (MAbs) that recognized epitopes on domain III (DIII) of the E protein. To identify an analogous panel of neutralizing antibodies against DENV type-1 (DENV-1), we immunized mice with a genotype 2 strain of DENV-1 virus and generated 79 new MAbs, 16 of which strongly inhibited infection by the homologous virus and localized to DIII. Surprisingly, only two MAbs, DENV1-E105 and DENV1-E106, retained strong binding and neutralizing activity against all five DENV-1 genotypes. In an immunocompromised mouse model of infection, DENV1-E105 and DENV1-E106 exhibited therapeutic activity even when administered as a single dose four days after inoculation with a heterologous genotype 4 strain of DENV-1. Using epitope mapping and X-ray crystallographic analyses, we localized the neutralizing determinants for the strongly inhibitory MAbs to distinct regions on DIII. Interestingly, sequence variation in DIII alone failed to explain disparities in neutralizing potential of MAbs among different genotypes. Overall, our experiments define a complex structural epitope on DIII of DENV-1 that can be recognized by protective antibodies with therapeutic potential
Structural Dynamics Study of Hydration Shells on n-Ge(100) in Aqueous Solution with Electrochemical Control
Structural changes of the hydration shell of surfaces in aqueous solution are studied using attenuated total reflection infrared spectroscopy, under different electrode potentials and consequently different states of the solid/liquid interface
Vibrational spectroscopic study of pH dependent solvation at an Ge(100)-water interface during an electrode potential triggered surface termination transition.
The charge-dependent structure of interfacial water at the n-Ge(100)-aqueous perchlorate interface was studied by controlling the electrode potential. Specifically, a joint attenuated total reflection infrared spectroscopy and electrochemical experiment was used in 0.1M NaClO4 at pH ≈ 1–10. The germanium surface transformation to an H-terminated surface followed the thermodynamic Nernstian pH dependence and was observed throughout the entire pH range. A singular value decomposition-based spectra deconvolution technique coupled to a sigmoidal transition model for the potential dependence of the main components in the spectra shows the surface transformation to be a two-stage process. The first stage was observed together with the first appearance of Ge–H stretching modes in the spectra and is attributed to the formation of a mixed surface termination. This transition was reversible. The second stage occurs at potentials ≈0.1–0.3 V negative of the first one, shows a hysteresis in potential, and is attributed to the formation of a surface with maximum Ge–H coverage. During the surface transformation, the surface becomes hydrophobic, and an effective desolvation layer, a “hydrophobic gap,” developed with a thickness ≈1–3 Å. The largest thickness was observed near neutral pH. Interfacial water IR spectra show a loss of strongly hydrogen-bound water molecules compared to bulk water after the surface transformation, and the appearance of “free,” non-hydrogen bound OH groups, throughout the entire pH range. Near neutral pH at negative electrode potentials, large changes at wavenumbers below 1000 cm−1 were observed. Librational modes of water contribute to the observed changes, indicating large changes in the water structure
Edge-enriched 2D MoS2 thin films grown by chemical vapor deposition for enhanced catalytic performance
Chemical vapor deposition (CVD) is used to grow thin films of 2D MoS2 with nanostructure for catalytic applications in the hydrogen evolution reaction (HER). Tailoring of the CVD parameters results in an optimized MoS2 structure for the HER that consists of large MoS2 platelets with smaller layered MoS2 sheets growing off it in a perpendicular direction, which increases the total number of edge sites within a given geometric area. A surface area to geometric area ratio of up to ∼340 is achieved, benefiting from the edge-exposed high-porosity network structure. The optimized thickness of the MoS2 film is determined for maximum performance, revealing that increasing thickness leads to increased impedance of the MoS2 film and reduced current density. The current density of the optimum sample reaches as high as 60 mA/cm2geo (normalized by geometric area) at an overpotential of 0.64 V vs RHE (in 0.5 M H2SO4), with a corresponding Tafel slope of ∼90 mV/dec and exchange current density of 23 μA/cm2geo. The lowered Tafel slope and large exchange current density demonstrate that the high-porosity edge-exposed MoS2 network structure is promising as a HER catalyst
Solution-Processed Cesium Hexabromopalladate(IV), Cs<sub>2</sub>PdBr<sub>6</sub>, for Optoelectronic Applications
Lead
halide perovskites are materials with excellent optoelectronic
and photovoltaic properties. However, some hurdles remain prior to
commercialization of these materials, such as chemical stability,
phase stability, sensitivity to moisture, and potential issues due
to the toxicity of lead. Here, we report a new type of lead-free perovskite
related compound, Cs<sub>2</sub>PdBr<sub>6</sub>. This compound is
solution processable, exhibits long-lived photoluminescence, and an
optical band gap of 1.6 eV. Density functional theory calculations
indicate that this compound has dispersive electronic bands, with
electron and hole effective masses of 0.53 and 0.85 m<sub>e</sub>,
respectively. In addition, Cs<sub>2</sub>PdBr<sub>6</sub> is resistant
to water, in contrast to lead-halide perovskites, indicating excellent
prospects for long-term stability. These combined properties demonstrate
that Cs<sub>2</sub>PdBr<sub>6</sub> is a promising novel compound
for optoelectronic applications
Edge-Enriched 2D MoS<sub>2</sub> Thin Films Grown by Chemical Vapor Deposition for Enhanced Catalytic Performance
Chemical vapor deposition (CVD) is
used to grow thin films of 2D
MoS<sub>2</sub> with nanostructure for catalytic applications in the
hydrogen evolution reaction (HER). Tailoring of the CVD parameters
results in an optimized MoS<sub>2</sub> structure for the HER that
consists of large MoS<sub>2</sub> platelets with smaller layered MoS<sub>2</sub> sheets growing off it in a perpendicular direction, which
increases the total number of edge sites within a given geometric
area. A surface area to geometric area ratio of up to ∼340
is achieved, benefiting from the edge-exposed high-porosity network
structure. The optimized thickness of the MoS<sub>2</sub> film is
determined for maximum performance, revealing that increasing thickness
leads to increased impedance of the MoS<sub>2</sub> film and reduced
current density. The current density of the optimum sample reaches
as high as 60 mA/cm<sup>2</sup><sub>geo</sub> (normalized by geometric
area) at an overpotential of 0.64 V vs RHE (in 0.5 M H<sub>2</sub>SO<sub>4</sub>), with a corresponding Tafel slope of ∼90 mV/dec
and exchange current density of 23 μA/cm<sup>2</sup><sub>geo</sub>. The lowered Tafel slope and large exchange current density demonstrate
that the high-porosity edge-exposed MoS<sub>2</sub> network structure
is promising as a HER catalyst
A tunable metal–polyaniline interface for efficient carbon dioxide electro-reduction to formic acid and methanol in aqueous solution
It is reported that metals on polyaniline (PANI) prepared by a simple method can exhibit excellent activity in the electro-reduction of CO2 to HCOOH or CH3OH due to tunable properties: N atoms on PANI capture CO2 through a strong Lewis acid-base interaction while Pd atoms, amongst Pd, Pt, and Cu studied, facilitate the fastest proton and electron transfers along PANI to the CO2 trapped sites to give rise to the best HCOOH yield in a highly cooperative manner