A pH-Induced Reversible Conformational Switch Able to Control the Photocurrent Efficiency in a Peptide Supramolecular System

External stimuli are potent tools that Nature uses to control protein function and activity. For instance, during viral entry and exit, pH variations are known to trigger large protein conformational changes. In Nature, also the electron transfer (ET) properties of ET proteins are influenced by pH-induced conformational changes. In this work, a pH-controlled, reversible 3₁₀-helix to α-helix conversion (from acidic to highly basic pH values and vice versa) of a peptide supramolecular system built on a gold surface is described. The effect of pH on the ability of the peptide SAM to generate a photocurrent was investigated, with particular focus on the effect of the pH-induced conformational change on photocurrent efficiency. The films were characterized by electrochemical and spectroscopic techniques, and were found to be very stable over time, also in contact with a solution. They were also able to generate current under illumination, with an efficiency that is the highest recorded so far with biomolecular systems.     

Amphoteric 2-(sulfonylamino)benzaldehydes,secondary amines and isocyanides in the multicomponent synthesis of elusive N-alkyl-2,3-diaminoindoles

A novel interrupted Ugi reaction between ortho-sulfonylaminated aryl aldehydes, secondary amines, and isocyanides affords in good to high yields N-alkyl-2,3-diaminoindoles, providing access to a so far unexplored area of the indole chemical space. With only one single chemical operation, this novel reaction affords a broad gamma of substituted 2,3-diaminoindoles with five points of diversity. The success of this novel multicomponent transformation lies in presence of the amphoteric sulfonylamino group, which sequentially acts as a Brønsted acids and as a nucleophile the lack of need for additional catalysts and the high atom economy, with the loss of only one molecule of water, renders this approach a very effective one.     

Silver nanoparticles as potential antiviral agents

Virus infections pose significant global health challenges, especially in view of the fact that the emergence of resistant viral strains and the adverse side effects associated with prolonged use continue to slow down the application of effective antiviral therapies. This makes imperative the need for the development of safe and potent alternatives to conventional antiviral drugs. In the present scenario, nanoscale materials have emerged as novel antiviral agents for the possibilities offered by their unique chemical and physical properties. Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses including human imunodeficiency virus, hepatitis B virus, herpes simplex virus, respiratory syncytial virus, and monkey pox virus. The use of metal nanoparticles provides an interesting opportunity for novel antiviral therapies. Since metals may attack a broad range of targets in the virus there is a lower possibility to develop resistance as compared to conventional antivirals. The present review focuses on the development of methods for the production of silver nanoparticles and on their use as antiviral therapeutics against pathogenic viruses.     

Discovery of novel anti-HIV active G-quadruplex-forming oligonucleotides

A series of d((5')TGGGAG(3')) sequences, 5'-conjugated with a variety of aromatic groups through phosphodiester linkages, were synthesized, showing CD spectra diagnostic of parallel-stranded, tetramolecular G-quadruplex structures. When tested for anti-HIV-1 and HIV-2 activity, potent inhibition of HIV-1 infection in CEM cell cultures was found, associated with high selectivity index values. Surface Plasmon Resonance assays revealed specific binding to HIV-1 gp120 and gp41.     

Optimization of a 2D photonic crystal add/drop multiplexer based on contra-directional coupling

We present a highly integrated add/drop multiplexer, where the contra-directional coupling is realized by phase matching two photonic crystal waveguides. The device band structure, the corresponding transmission and drop spectra, and the coupling length are carefully analysed. Different device configurations are discussed and by tailoring the coupling factor, we optimize the frequency response of the filter, obtaining a -sized channel selector, characterized by a very high drop efficiency.     

LocalMV-algebras

In this paper we examine and classify the class of localMV-algebras, pointing out some topological properties of them. Particulary we study theMV-algebras generated by radical: some of these algebras are non-linear generalizations of theMV-algebra C defined by C. C. Chang [4].     

Nitration of substituted chromans

The nitration of substituted chromans has been studied and the structure of the nitro compounds has been confirmed by chemical and spectral data.     

Non-hydrolytic chemoselective cleavage of Ugi tertiary amides: A mild access to N-substituted α-amino acid amides

N-Substituted α-amino acid amides can be easily obtained in two steps using the four-component Ugi reaction followed by chemoselective cleavage of the resulting tertiary amide. The use of the sacrificial acid, 2-hydroxymethylbenzoic acid is associated to shorter reaction times, higher yields, and safer and greener reaction conditions compared to strategies based on trifluoroacetic acid, a toxic and environmental hazardous reagent. The optimized procedure was easily scaled up to gram amounts.