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The fabrication and properties of anisotropic gold nanoparticles (AuNPs) are of great interest from fundamental and application standpoints. Whereas various neutral ferrocene derivatives have been shown to reduce AuIII to Au0NPs owing to slightly exergonic electron transfer in biphasic systems, the question remained open for water soluble ferrocenes containing electron withdrawing substituents increasing the FeIII/FeII oxidation potential. Here, it is shown that reaction of sodium ferrocene carboxylate, NaFcCO2, alone, does not reduce H[AuIIICl4] to stable AuNPs under ambient conditions in water. On the other hand, reaction between NaFcCO2 and H[AuIIICl4] in water in the presence of poly (vinyl pyrrolidone) (PVP), citrate or other 1,2,3‐triazole (trz)‐containing stabilizers is shown to produce catalytically active Au nanocrystals with various shapes. EDX results confirm the fixation of the ferrocenyl carboxylate ligand onto the AuNP surface. 4‐nitrophenol reduction to 4‐aminophenol by Na[BH4] in water proceeds in the presence of the various stabilizers, without induction time in most cases, which confirms the weakness of the ferrocenyl carboxylate ligand bonded to the AuNP surface and the favorable role of ferrocenyl carboxylate ligand for catalysis at the AuNP surface. [ABSTRACT FROM AUTHOR]

The enzyme-free, DNA-templated polymerization of side-chain-functionalized peptide nucleic acid (PNA) tetramer and pentamer aldehydes is described. The results have shown that enzyme-free nucleic acid-templated polymerization has occurred efficiently by using substrates with a wide range of side-chain structures, functionalization positions within each building block functionalization densities.

Rhodococcus ruber GIN1 (formally Rh. strain GIN1) was previously isolated on the basis of its strong adherence to coal fly ash (CFA) and titanium dioxide particles from CFA sedimentation ponds of an electrical power plant in Israel. The interaction of the bacterium with oxides has been shown to be mediated by a cell surface protein designated TiBP (titanium binding protein) involving primarily strong, non-electrostatic forces. In this work, we set forward to identify this unique exocellular protein. Sequence analysis of the purified protein by mass spectrometry (LC/MS/MS) following trypsinization revealed 11 peptides. All of them showed >90% amino acid residues identity with sequences of one of the orthologs (dldh1) of the cytosolic enzyme dihydrolipoamide dehydrogenase (DLDH), based on the genome sequence of Rhodococcus strain RHA1. This genome was selected as a reference since currently it is the only sequenced Rhodococcal genome. Altogether, these peptides covered over 25% of the 52 kDa protein molecule. N- and C-termini primers were prepared and used to sequence the paralog gene from Rh. ruber GIN1 after polymerase chain reaction (PCR) amplification. All 11 peptides showed 100% identity with the sequence of this gene. The homology of TiBP with the supposedly cytosolic DLDH raised the question of whether the exocellular TiBP possesses DLDH activity. Indeed, intact late logarithmic phase Rh. ruber GIN1 cells, previously shown to express TiBP, were found to possess such activity, while very low activity was associated with stationary phase cells which possess diminished TiBP expression on their surface. Further evidence for the exocellular location of TiBP/DLDH was achieved using specific anti-TiBP polyclonal antibodies by whole cell and protein enzyme-linked immunosorbent assay (ELISA), showing high reactivity of the logarithmic phase cell surface and substantially lower reactivity with the stationary phase cells. As expected, logarithmic phase spheroplasts were not recognized by these antibodies. Similar results were obtained by fluorescence and scanning electron microscopy. Our postulation that DLDH is located on the surface of Rh. ruber GIN1, serving as a TiO2 binding protein, is in accordance with literary evidence on DLDH in other organisms, Bacteria, Archea, and Eukaryots that suggests it is associated with the outer membranes or cell surfaces. As an exocellular protein DLDH assumes various tasks which are not related to its classical role as a 2-oxoacid dehydrogenase, including serving as an adhesion/binding protein in certain bacteria. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]