Gold nanostars have attracted widespread interest due to their remarkable properties and broad applications in plasmonics, spectroscopy, biomedicine, and energy conversion. However, current synthetic methods of Au nanostars have limited control over their symmetry; most existing nanostars are characterized by having uncertain number of arms with different lengths and random spatial arrangement. This morphological arbitrariness not only hampers the fundamental understanding of the properties of Au nanostars, but also lead to poor reproducibility in their applications. Here we demonstrate that, by using a robust solution-phase method, Au nanostars with unpreceded degree of symmetry control can be obtained in high yield and with remarkable monodispersity. Icosahedral seeds are used to dictate the growth of 3D evenly distributed arms in an Ih symmetric manner. Alkylamines serve as shape-control agent to regulate the growth of the hexagonal pyramidal arms enclosed by high-index facets. Benefiting from their high symmetry, the Au nanostars exhibit superior single-particle SERS performance compared to asymmetric Au nanostars, in terms of both intensity and reproducibility.

Thioredoxin glutathione reductase from Schistosoma mansoni (SmTGR) catalyzes the reduction of both thioredoxin and glutathione disulfides (GSSG), thus playing a crucial role in maintaining redox homeostasis in the parasite. In line with this role, previous studies have demonstrated that SmTGR is a promising drug target for schistosomiasis. To aid in the development of efficacious drugs that target SmTGR, it is essential to understand the catalytic mechanism of SmTGR. SmTGR is a dimeric flavoprotein in the glutathione reductase family and it has a head-to-tail arrangement of its monomers; each subunit has the components of both a thioredoxin reductase (TrxR) domain and a glutaredoxin (Grx) domain. However, the active site of the TrxR domain is composed of residues from both subunits: FAD and a redox-active Cys-154/Cys-159 pair from one subunit and a redox-active Cys-596′/Sec-597′ pair from the other; the active site of the Grx domain contains a redox-active Cys-28/Cys-31 pair. Via its Cys-28/Cys-31 dithiol and/or its Cys-596′/Sec-597′ thiol-selenolate, SmTGR can catalyze the reduction of a variety of substrates by NADPH. It is presumed that SmTGR catalyzes deglutathionylation reactions via the Cys-28/Cys-31 dithiol. Our anaerobic titration data suggest that reducing equivalents from NADPH can indeed reach the Cys-28/Cys-31 disulfide in the Grx domain to facilitate reductions effected by this cysteine pair. To clarify the specific chemical roles of each redox-active residue with respect to its various reactivities, we generated variants of SmTGR. Cys-28 variants had no Grx glutathionylation activity whereas Cys-31 variants retained partial Grx glutathionylation activity, indicating that the Cys-28 thiolate is the nucleophile initiating deglutathionylation. Lags in the steady-state kinetics, found when wild-type (WT) SmTGR was incubated at high concentrations of GSSG, were not present in Grx variants, indicating that this cysteine pair is in some way responsible for the lags. A Sec-597 variant was still able to reduce a variety of substrates, albeit slowly, showing that selenocysteine is important but is not the sole determinant for the broad substrate tolerance of the enzyme. Our data show that Cys-520 and Cys-574 are not likely to be involved in the catalytic mechanism.

The long-range ordering and directed self-assembly of thin films of a high interaction parameter rod–coil liquid crystalline block copolymer (LC BCP), poly­(dimethylsiloxane)-b-poly­{2,5-bis­[(4-methoxyphenyl)-oxycarbonyl]­styrene} (PDMS-b-PMPCS, or DM), is described. The LC BCP was spin-coated on a polystyrene brush functionalized substrate and then thermally annealed at different temperatures with respect to the LC ordering temperature. The effects of the wetting behavior, commensurability between the film thickness and the periodicity, and the LC orientation on the ordering and orientation of the microdomains are described. A monolayer of in-plane cylinders with excellent long-range ordering was produced, and was transferred into SiO x patterns with tunable sub-10 nm feature sizes. Well-ordered multilayer in-plane cylinders were produced in thicker films, and the correlation between microstructure evolution and the LC ordering process was studied by grazing-incidence small-angle X-ray scattering (GISAXS) and wide-angle X-ray scattering (GIWAXS). Finally, the cylindrical rod–coil BCP was directed into a novel ladder morphology within lithographically patterned substrate trenches, as well as into patterns of parallel or transverse cylinders. The ordering of cylinders, the ladder morphology, and the etch selectivity and thermal stability of this high-interaction parameter silicon-containing LC rod–coil BCP demonstrate its applicability to nanoscale lithography.

Gastric cancer is a leading cause of death worldwide, and patients have an overall 5-year survival rate of less than 10%. Using quantitative proteomic techniques together with microarray chips, we have established comprehensive proteome and transcriptome profiles of the metastatic gastric cancer TMC-1 cells and the noninvasive gastric cancer SC-M1 cell. Our qualitative protein profiling strategy offers the first comprehensive analysis of the gastric cancer cell proteome, identifying 926 and 909 proteins from SC-M1 and TMC-1 cells, respectively. Cleavable isotope-coded affinity tagging analysis allows quantitation of a total of 559 proteins (with a protein false-positive rate of <0.005), and 240 proteins were differentially expressed (>1.3-fold) between the SC-M1 and TMC-1 cells. We identified numerous proteins not previously associated with gastric cancer. Notably, a large subset of differentially expressed proteins was associated with tumor metastasis, including proteins functioning in cell-cell and cell-extracellular matrix (cell-ECM) adhesion, cell motility, proliferation, and tumor immunity. Gene expression profiling by DNA microarray revealed differential expression (of >2-fold) of about 1000 genes. The weak correlation observed between protein and mRNA profiles highlights the important complementarities of DNA microarray and proteomics approaches. These comparative data enabled us to map the disease-perturbed cell-cell and cell-ECM adhesion and Rho GTPase-mediated cytoskeletal pathways. Further validation of a subset of genes suggests the potential use of vimentin and galectin 1 as markers for metastasis. We demonstrate that combining proteomic and genomic approaches not only provides a rapid, robust, and sensitive platform to elucidate the molecular mechanisms underlying gastric cancer metastasis but also may identify candidate diagnostic markers and therapeutic targets.