An All-Photonic Molecule-Based D Flip-Flop

The photochromic fluorescence switching of a fulgimide derivative was used to implement the first molecule-based D (delay) flip-flop device, which works based on the principles of sequential logic. The device operates exclusively with photonic signals and can be conveniently switched in repeated cycles. \ua9 2011 American Chemical Society

Hepatitis C Virus Antigenic Convergence

Vaccine development against hepatitis C virus (HCV) is hindered by poor understanding of factors defining cross-immunoreactivity among heterogeneous epitopes. Using synthetic peptides and mouse immunization as a model, we conducted a quantitative analysis of cross-immunoreactivity among variants of the HCV hypervariable region 1 (HVR1). Analysis of 26,883 immunological reactions among pairs of peptides showed that the distribution of cross-immunoreactivity among HVR1 variants was skewed, with antibodies against a few variants reacting with all tested peptides. The HVR1 cross-immunoreactivity was accurately modeled based on amino acid sequence alone. The tested peptides were mapped in the HVR1 sequence space, which was visualized as a network of 11,319 sequences. The HVR1 variants with a greater network centrality showed a broader cross-immunoreactivity. The entire sequence space is explored by each HCV genotype and subtype. These findings indicate that HVR1 antigenic diversity is extensively convergent and effectively limited, suggesting significant implications for vaccine development

Synthesis and Properties of Achiral Asymmetric Dinuclear Tris(1-pyrazolyl)methane Complexes of Ru(II).

Exploiting the “complexes-as-metals/complexes-as-ligands” synthetic strategy [1] a family of six novel polypyridyl dinuclear species containing two different Ru tpm)(CL) units [tpm = tris(1- pyrazolyl)methane, CL = 2,2’-bipyridine, 1,10-phenanthroline, 2,2’-biquinoline] bridged either by 4,4’-bipyridine or pyrazine (see the chart) have been prepared as hexafluorophosphate salts. These compounds re-present the asymmetric analogues of six dinuclear complexes whose synthesis and properties have been recently published. Notably, owing to the presence of a tripodal ligand, the metal centres are not chiral, thus the samples are not diastereomeric mixtures, a feature that prevents the structural characterization of oligonuclear trischelate complexes. All novel complexes have been thoroughly characterized by elemental analyses and IR spectroscopy, and their 1H NMR spectra completely assigned on the basis of COSY and NOESY experiments. The photophysical, electrochemical, and spectroelectrochemical properties of the new species have also been studied

High prevalence of hypervariable region 1-specific and -cross-reactive CD4(+) T cells in HCV-infected individuals responsive to IFN-alpha treatment

The hypervariable region 1 (HVR1) of the putative envelope 2 protein of the hepatitis C virus (HCV) is the most variable part of the whole HCV polyprotein. Anti-HVR1 antibodies have been shown to protect against HCV infection, indicating that this region contains an important neutralization determinant Recently we and others have demonstrated that HVR1 is also a T cell determinant able to activate helper T cell responses during HCV infection. In order to investigate the role of the immune response against HVR1 during HCV infection we have evaluated the humoral and lymphoproliferative responses to a panel of HVR1 peptides in HCV-infected patients with different outcomes of the disease following interferon-alpha (IFN-alpha) treatment We observed that the frequency of anti-HVR1 T cell responses was significantly higher in patients who recovered after IFN-alpha therapy than in those who did not, while no differences in the anti-HVR1 antibody reactivities were detected. In addition, by generating HVR1-specific T cell lines and clones we identified human leukocyte-associated antigens DR4 restricted T cell epitopes in the carboxy-terminus of HVR1 and we demonstrated that broadly cross-reactive HVR1 T cells are elicited by HVR1. (C) 2000 Academic Press

Synthesis, photophysical and redox behaviour of unsymmetrical binuclear Ru(II) complexes based on tris(1-pyrazolyl)methane

Six new unsymmetrical achiral complexes of RuII containing the tripodal ligand tris(1-pyrazolyl)methan (tpm) on both metal centers have been prepared and fully characterized. Their general formula is [CLa(tpm)Ru(μBL)Ru(tpm)CLb]4+, were CLa and CLb represent two different chelating ligands (2,2′-bipyridine (bpy), 1,10-phenanthroline (phen) or 2,2′-biquinoline (biq)); BL can be 4,4′-bipyridine (4,4′-bpy) or pirazine (pz). The structures of the new species have been elucidated by 1H NMR, COSY and NOESY spectroscopy. Electrochemical, UV–Vis spectroscopical, luminescence, and spectroelectrochemical properties have been investigated for all the binuclear complexes. For two representative species DFT calculations were carried out. The experimental data have been thoroughly interpreted in terms of the role played by each constituent subunit within the assemblies. These results add comparative pieces of information to the knowledge of the properties of the RuII-based complexes

Photo-induced water oxidation: New photocatalytic processes and materials

New progress towards artificial photosynthetic methods and solar fuels will depend on the discovery of highly robust multi-electron catalysts and materials enabling light-activated water splitting with high quantum efficiency and low overpotential, thus mimicking the natural process

Photo-induced water oxidation with tetra-nuclear ruthenium sensitizer and catalyst: A unique 4 x 4 ruthenium interplay triggering high efficiency with low-energy visible light

The combined use of a tetranuclear Ru(II) dendrimeric photosensitizer and of a tretraruthenium substituted polyoxotungstate as the catalyst enables photo-induced water oxidation at 550 nm producing O2 with an outstanding quantum yield of 0.30