Oligopeptide Helical Conformations Control Gold Nanoparticle Cross-Linking

Peptide sequences functionalized with primary amines at the N- and C-terminus are able to induce the aggregation of gold nanoparticles in ethanol as a consequence of their folding into a helical conformation. Random coil peptides are unable to induce such an aggregation process. Aggregation can be monitored spectrophotometrically by following the shift of the surface plasmon resonance (SPR) band of the nanoparticles and is confirmed by transmission electron microscopy and dynamic light scattering analyses. Partial denaturation of the peptides results in diminished cross-linking ability. The helicity parameter θ₂₂₂/θ₂₀₈ correlates fairly well with the shift of the SPR band to longer wavelengths, supporting the relationship between the amount of helical content of a peptide sequence and its ability to induce aggregation.     

A Supramolecular Palladium Catalyst Displaying Substrate Selectivity by Remote Control

Inspired by enzymes such as cytochrome P-450, the study of the reactivity of metalloporphyrins continues to attract major interest in the field of homogeneous catalysis. However, little is known about benefitting from the substrate-recognition properties of porphyrins containing additional, catalytically relevant active sites. Herein, such an approach is introduced by using supramolecular ligands derived from metalloporphyrins customized with rigid, palladium-coordinating nitrile groups. According to different studies (NMR and UV/Vis spectroscopy, XRD, control experiments), the supramolecular ligands are able to accommodate pyridine derivatives as substrates inside the porphyrin pocket while the reactivity occurs at the peripheral side. By simply tuning a remote metal center, different binding events result in different catalyst reactivity, and this enzyme-like feature leads to high degrees of substrate selectivity in representative palladium-catalyzed Suzuki–Miyaura reactions.     

Starshapedness of the superlevel sets of solutions to equations involving the fractional Laplacian in starshaped rings

We study solutions of the problem (0.1) where are open sets such that , , and f is a nonlinearity. Under different assumptions on f we prove that, if D₀ and D₁ are starshaped with respect to the same point , then the same occurs for every superlevel set of u.     

Third-Order Phase Transition: Random Matrices and Screened Coulomb Gas with Hard Walls

Journal of Statistical Physics - Consider the free energy of a d-dimensional gas in canonical equilibrium under pairwise repulsive interaction and global confinement, in presence of a volume...