Bacterial nanowires are extracellular appendages that have been suggested as pathways for electron transport in phylogenetically diverse microorganisms, including dissimilatory metal-reducing bacteria and photosynthetic cyanobacteria. However, there has been no evidence presented to demonstrate electron transport along the length of bacterial nanowires. Here we report electron transport measurements along individually addressed bacterial nanowires derived from electron-acceptor–limited cultures of the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1. Transport along the bacterial nanowires was independently evaluated by two techniques: ( i ) nanofabricated electrodes patterned on top of individual nanowires, and ( ii ) conducting probe atomic force microscopy at various points along a single nanowire bridging a metallic electrode and the conductive atomic force microscopy tip. The S. oneidensis MR-1 nanowires were found to be electrically conductive along micrometer-length scales with electron transport rates up to 10 9 /s at 100 mV of applied bias and a measured resistivity on the order of 1 Ω·cm. Mutants deficient in genes for c -type decaheme cytochromes MtrC and OmcA produce appendages that are morphologically consistent with bacterial nanowires, but were found to be nonconductive. The measurements reported here allow for bacterial nanowires to serve as a viable microbial strategy for extracellular electron transport.

A new amino-functionalized polymer, PN4N, was developed and applied as an efficient interlayer to improve the cathode interface of fullerene/perovskite (CH3NH3PbIxCl3−x) planar heterojunction solar cells.

TiO2 photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO2 nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO2 and Ag-TiO2 composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO2 and TiO2 films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO2 matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag(0) state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm(-2) and in the dark respectively. The synthesized Ag-TiO2 thin films showed enhanced bactericidal activities compared to the neat TiO2 nanofilm both in the dark and under UV illumination.

The study of electrical transport in biomolecular materials is critical to our fundamental understanding of physiology and to the development of practical bioelectronics applications. In this study, we investigated the electronic transport characteristics of Shewanella oneidensis MR-1 nanowires by conducting-probe atomic force microscopy (CP-AFM) and by constructing field-effect transistors (FETs) based on individual S. oneidensis nanowires. Here we show that S. oneidensis nanowires exhibit p-type, tunable electronic behavior with a field-effect mobility on the order of 10(-1) cm(2)/(V s), comparable to devices based on synthetic organic semiconductors. This study opens up opportunities to use such bacterial nanowires as a new semiconducting biomaterial for making bioelectronics and to enhance the power output of microbial fuel cells through engineering the interfaces between metallic electrodes and bacterial nanowires.

Parallel-displaced pi-pi stacking interactions have been known to be the dominant force in stabilizing the double helical structure of DNA and the tertiary structure of proteins. However, little is known about their roles in self-assembled monolayers of other large pi molecules such as aromatic thiols. Here we report on a systematic study of the self-assembled monolayers of four kinds of anthracene-based thiols, 9-mercaptoanthracene (MA), (4-mercaptophenyl) (9-anthryl) acetylene (MPAA), (4-mercaptophenyl) (10-nitro-9-anthryl) acetylene (MPNAA), and (4-mercaptophenyl) (10-carboxyl-9-anthryl) acetylene (MPCAA) on Au(111), in which a spacer and different functional groups (NO2 and COOH) are intentionally designed to introduce and thus allow the investigation of various intermolecular interactions, in addition to pi-pi interactions in the base molecules. We find that all molecules form long-range-ordered monolayers and, more interestingly, that these assembled monolayers exhibit essentially the same fundamental packing structure. On the basis of high-resolution scanning tunneling microscopy observations, we propose the space-filling models for the observed superstructures and demonstrate that all superstructures can be understood in terms of the parallel-displaced pi-pi stacking interactions, despite the presence of competing dipole-dipole and H-bonding interactions associated with these specially designed functional groups.