Electrical and structural properties of stepped,partially reconstructed Au(11n) surfaces in HClO4 and H2SO4 electrolytes

We have studied the interface capacitance and the voltammograms of Au(11n) (n = 5, 7, 11, 17) and of Au(100) electrodes in 5 mM HClO₄ and 5 mM H₂SO₄ after immersion into the electrolyte solution at ?0.4 V versus a saturated calomel electrode. The minima of the capacitance curves measured in positive sweeps continuously shift towards positive potentials as function of 1/n. All voltammograms, even that of Au(1 1 5), display peaks that are characteristic for lifting of surface reconstructions, albeit at different potentials. Thus, all vicinal surfaces appear to have at least sections that allow reconstruction. This inference is consistent with STM-profiles of an Au(1 1 9) surface which displays a wide range of local inclination angles corresponding to local (11n)-orientations with 3.5 < n < ∞. A numerical analysis of the voltammograms shows the existence of three different ranges of transition potentials for the lifting of the reconstruction. The transition potentials are assigned to three different structures of the reconstructed phase as either observed by experiment or proposed by theory.     

Acid-Resistant BODIPY Amino Acids for Peptide-Based Fluorescence Imaging of GPR54 Receptors in Pancreatic Islets

The G protein-coupled kisspeptin receptor (GPR54 or KISS1R) is an important mediator in reproduction, metabolism and cancer biology; however, there are limited fluorescent probes or antibodies for direct imaging of these receptors in cells and intact tissues, which can help to interrogate their multiple biological roles. Herein, we describe the rational design and characterization of a new acid-resistant BODIPY-based amino acid (Trp-BODIPY PLUS), and its implementation for solid-phase synthesis of fluorescent bioactive peptides. Trp-BODIPY PLUS retains the binding capabilities of both short linear and cyclic peptides and displays notable turn-on fluorescence emission upon target binding for wash-free imaging. Finally, we employed Trp-BODIPY PLUS to prepare some of the first fluorogenic kisspeptin-based probes and visualized the expression and localization of GPR54 receptors in human cells and in whole mouse pancreatic islets by fluorescence imaging.