Controlling the Adsorption of Ruthenium Complexes on Carbon Surfaces through Noncovalent Bonding with Pyrene Anchors: An Electrochemical Study

Surface modifications of carbon nanomaterials, such as graphene or carbon nanotubes, through noncovalent π–π interactions between π-conjugated carbon surfaces and pyrene anchors have received much attention on account of the applications of these materials in organic electronic and sensor devices. Despite the rapidly expanding use of pyrene anchors, little is known about the number of pyrene groups required in order to achieve a stable attachment of molecules on nanocarbon surfaces. So far, systematic studies on such surface modifications through adsorption isotherms and desorption behavior of molecules still remain scarce. In this study, we have investigated the effect of the number of pyrene anchors in redox-active Ru complexes on their adsorption on carbon nanomaterials through noncovalent π–π interactions. The Ru­(II/III) couple was used as a redox marker in order to determine the surface coverage on nanocarbon surfaces such as highly oriented pyrolytic graphite (HOPG), single-walled carbon nanotubes (SWCNTs), and multiwalled carbon nanotubes (MWCNTs). The amount of surface coverage as well as the kinetic stability of the Ru complexes was thereby observed to be directly proportional to the number of pyrene groups present in the ligands. The desorption rate from HOPG electrode increased in the order <b>Ru-1</b> with eight pyrene groups (<i>k</i> = 2.0 × 10^–5 s^–1) < <b>Ru-2</b> with four pyrenes (4.1 × 10^–5 s^–1) < <b>Ru-3</b> with two pyrenes (6.8 × 10^–5 s^–1) ≪ <b>Ru-4</b> with one pyrene (4.1 × 10^–3 s^–1). Furthermore, the electrochemical polymerization of the Ru complex with four pyrene groups proceeded more efficiently compared to complexes with one or two pyrene groups. As a consequence, compounds having more than two and/or optimally four pyrene groups revealed a stable adsorption on the nanocarbon surfaces. The heterogeneous electron transfer rate between the Ru complex, <b>Ru-2</b>, and the carbon nanomaterials increased in the order SWCNTs (<i>k</i>_ET = 1.3 s^–1) < MWCNTs (ϕ = 5–9 nm) (<i>k</i>_ET = 4.0 s^–1) < MWCNTs (ϕ = 110–170 nm) (<i>k</i>_ET = 14.9 s^–1) < HOPG (<i>k</i>_ET = 110 s^–1)

GWAS for systemic sclerosis identifies six novel susceptibility loci including one in the Fcγ receptor region

Abstract Here we report the largest Asian genome-wide association study (GWAS) for systemic sclerosis performed to date, based on data from Japanese subjects and comprising of 1428 cases and 112,599 controls. The lead SNP is in the FCGR/FCRL region, which shows a penetrating association in the Asian population, while a complete linkage disequilibrium SNP, rs10917688, is found in a cis-regulatory element for IRF8. IRF8 is also a significant locus in European GWAS for systemic sclerosis, but rs10917688 only shows an association in the presence of the risk allele of IRF8 in the Japanese population. Further analysis shows that rs10917688 is marked with H3K4me1 in primary B cells. A meta-analysis with a European GWAS detects 30 additional significant loci. Polygenic risk scores constructed with the effect sizes of the meta-analysis suggest the potential portability of genetic associations beyond populations. Prioritizing the top 5% of SNPs of IRF8 binding sites in B cells improves the fitting of the polygenic risk scores, underscoring the roles of B cells and IRF8 in the development of systemic sclerosis. The results also suggest that systemic sclerosis shares a common genetic architecture across populations