Quantitative differential proteomics for analysis of posttranslational modifications of proteins

In this work we developed a new and convenient method for high resolution IEF of proteins, which we termed: “daisy chain”. Usually an IEF is accomplished with IPG strips of a desired pH range. For high resolution focusing we are using strips with pH range, which covers only one or two pH units. Thereby the pro-teins, which have isoelectrical point outside of this pH range, are lost. We evalu-ated commercially available IPG strips with consecutive or overlapping pH ranges and connected them serially acidic to basic end, to construct in this way a high resolution IEF-system. For the first time, we showed that a high resolution IEF is possible in such a system and that results were by no means worse than those obtained when the same sample was analyzed on individual single IPGs. The great advantage of our system is that amount of sample used in serial IPG IEF is explicitly lower than when same sample was analyzed on individual single IPGs. This method was subsequently successfully applied to valuable clinical samples from cancer patients and to mitochondrial preparations related to a European project in gerontology. We thus developed a suite of experimental strategies, which adequately address complex biological situations, in particular on the level of protein expression.

Bottom-up solution synthesis of structurally defined graphene nanoribbons

Graphene nanoribbons (GNRs), which are defined as nanometer-wide strips of graphene, are attracting an increasing attention as one on the most promising materials for future nanoelectronics. Unlike zero-bandgap graphene that cannot be switched off in transistors, GNRs possess open bandgaps that critically depend on their width and edge structures. GNRs were predominantly prepared through “top-down” methods such as “cutting” of graphene and “unzipping” of carbon nanotubes, but these methods cannot precisely control the structure of the resulting GNRs. In contrast, “bottom-up” chemical synthetic approach enables fabrication of structurally defined and uniform GNRs from tailor-made polyphenylene precursors. Nevertheless, width and length of the GNRs obtainable by this method were considerably limited. In this study, lateral as well as longitudinal extensions of the GNRs were achieved while preserving the high structural definition, based on the bottom-up solution synthesis. Initially, wider (~2 nm) GNRs were synthesized by using laterally expanded monomers through AA-type Yamamoto polymerization, which proved more efficient than the conventional A2B2-type Suzuki polymerization. The wider GNRs showed broad absorption profile extending to the near-infrared region with a low optical bandgap of 1.12 eV, which indicated a potential of such GNRs for the application in photovoltaic cells. Next, high longitudinal extension of narrow (~1 nm) GNRs over 600 nm was accomplished based on AB-type Diels–Alder polymerization, which provided corresponding polyphenylene precursors with the weight-average molecular weight of larger than 600,000 g/mol. Bulky alkyl chains densely installed on the peripheral positions of these GNRs enhanced their liquid-phase processability, which allowed their formation of highly ordered self-assembled monolayers. Furthermore, non-contact time-resolved terahertz spectroscopy measurements demonstrated high charge-carrier mobility within individual GNRs. Remarkably, lateral extension of the AB-type monomer enabled the fabrication of wider (~2 nm) and long (>100 nm) GNRs through the Diels–Alder polymerization. Such longitudinally extended and structurally well-defined GNRs are expected to allow the fabrication of single-ribbon transistors for the fundamental studies on the electronic properties of the GNRs as well as contribute to the development of future electronic devices.