Draft genome Sequence of Phosphate-Accumulating Bacterium Acinetobacter tandoii SC36 from a Mangrove Wetland Ecosystem Provides Insights into Elements of Phosphorus Removal.

Acinetobacter tandoii SC36 was isolated from a mangrove wetland ecosystem in the Dongzhaigang Nature Reserve in Haikou, China. This bacterium was found to have a capacity for polyphosphate accumulation. To provide insight into its phosphorus metabolism and facilitate its application in phosphorus removal, we developed a draft genome of this strain. KEGG (Kyoto Encyclopedia of Genes and Genomes) annotation revealed three ppk genes and several phosphate metabolic related pathways in the genome of SC36. These genome data of Acinetobacter tandoii SC36 will facilitate elucidation of the mechanism of polyphosphate accumulation.

Characterization of a novel mosquitocidal toxin of Cry50Ba and its potential synergism with other mosquitocidal toxins.

A putative toxin gene of cry50Ba was successfully expressed in E. coli cells and confirmed that the purified Cry50Ba toxin had very high toxic activity against Culex quinquefasciatus larvae. Furthermore, the potential synergism of Cry50Ba toxin with Cry2Aa, Cry4Aa and Cry11Aa at a ratio of 1:1 was investigated. Although no significant synergism with other toxins was observed, the Cry50Ba as a novel toxin could be used to delay rapid onset of resistance in mosquito.

Versatile Polymer Nanoparticles as Two-Photon-Triggered Photosensitizers for Simultaneous Cellular, Deep-Tissue Imaging, and Photodynamic Therapy.

Clinical applications of current photodynamic therapy (PDT) photosensitizers (PSs) are often limited by their absorption in the UV-vis range that possesses limited tissue penetration ability, leading to ineffective therapeutic response for deep-seated tumors. Alternatively, two-photon excited PS (TPE-PS) using NIR light triggered is one the most promising candidates for PDT improvement. Herein, multimodal polymer nanoparticles (PNPs) from polythiophene derivative as two-photon fluorescence imaging as well as two-photon-excited PDT agent are developed. The prepared PNPs exhibit excellent water dispersibility, high photostability and pH stability, strong fluorescence brightness, and low dark toxicity. More importantly, the PNPs also possess other outstanding features including: (1) the high 1 O2 quantum yield; (2) the strong two-photon-induced fluorescence and efficient 1 O2 generation; (3) the specific accumulation in lysosomes of HeLa cells; and (4) the imaging detection depth up to 2100 µm in the mock tissue under two-photon. The multifunctional PNPs are promising candidates as TPE-PDT agent for simultaneous cellular, deep-tissue imaging, and highly efficient in vivo PDT of cancer.

Label-free attomolar detection of proteins using integrated nanoelectronic and electrokinetic devices.

High-sensitivity screening of biomarkers is critical to areas ranging from early disease detection and diagnosis to bioterrorism surveillance. Here the development of integrated nanoelectronic and electrokinetic devices for label-free attomolar detection of proteins is reported. Electrically addressable silicon nanowire field-effect transistors and electrodes for electrokinetic transport are integrated onto a common sensor chip platform, and the nanowire devices are subsequently functionalized with receptors for selective biomarker detection. Nanowire devices modified with monoclonal antibody for prostate specific antigen exhibit close to a 10(4) increase in sensitivity due to streaming dielectrophoresis and corresponding electrostatic contribution to the binding affinity after application of an AC electric field. The devices are also modified with receptors for cholera toxin subunit B and achieve a similar enhancement. These results show general applicability of this method, and could open up opportunities in early stage disease detection and the analysis of proteins from single cells.

Controllable distribution of single molecules and peptides within oligomer template investigated by STM.

This communication provides a facile method for distributing and dispersing molecules within a molecular template. Using the self-assembled template of oligo(phenylene-ethynylene) (OPE), organic molecules such as coronene (COR) and biomolecules such as tripeptide are controllably distributed and dispersed within this molecular template on highly oriented pyrolytic graphite (HOPG) surfaces. COR molecules were controllably distributed into various regular arrays by simply adjusting the molecular molar ratio, while tripeptide molecules were uniformly positioned at the vacancies of the OPE template.

Molecular architecture of oligothiophene on a highly oriented pyrolytic graphite surface by employing hydrogen bondings.

To achieve a controllable and predictable molecular architecture on a two-dimensional (2D) surface, a series of oligothiophenes with carboxylic groups and alkane chains were synthesized. The alkane chains and carboxylic groups, which can form hydrogen bonding, were intentionally designed in different positions of the oligothiophenes. The resulted molecular architectures by using the so-prepared oligothiophenes on a highly oriented pyrolytic graphite (HOPG) surface were investigated by scanning tunneling microscopy (STM) and density functional theory (DFT). It is found that the hydrogen bonding plays an essential role in the formation of the ordered assemblies. A controlled 2D molecular assembly could be fabricated by using hydrogen bondings.

Mesoscopic self-organization of a self-assembled supramolecular rectangle on highly oriented pyrolytic graphite and Au(111) surfaces.

A self-assembled supramolecular metallacyclic rectangle was investigated with scanning tunneling microscopy on highly oriented pyrolytic graphite and Au(111) surfaces. The rectangles spontaneously adsorb on both surfaces and self-organize into well ordered adlayers. On highly oriented pyrolytic graphite, the long edge of the rectangle stands on the surface, forming a 2D molecular network. In contrast, the face of the rectangle lays flat on the Au(111) surface, forming linear chains. The structures and intramolecular features obtained through high-resolution scanning tunneling microscopy imaging are discussed.

Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under joule heating: an STM and photoluminescence study.

The Joule heating effect on electroluminescent efficiency is important in the degradation origin of organic light-emitting diodes (OLED). Scanning tunneling microscopy (STM) and photoluminescence (PL) measurements were performed on the guest molecule BT (1,4-bis(benzothiazole-vinyl) benzene), host molecule TPBI (2, 2',2' '-(1,3,5-phenylene)tris-[1-phenyl-1H-benzimidazole]), and their mixture deposited on an HOPG surface to study the OLED degradation mechanism due to thermal heating. At room temperature, BT and TPBI in the mixed layer show good compatibility and high PL intensity, but at higher temperatures, they show phase separation and aggregation into their own domains and a concomitant decrease in PL intensity. The PL intensity loss suggests ineffective energy transfer from TPBI to BT due to phase separation, which may cause OLED degradation. Scanning tunneling spectroscopy (STS) results show that the band gaps of TPBI and BT remain unchanged with the annealing temperature, suggesting that the heat-induced decay of OLED is related to the interfacial structural change rather than the respective molecular band gap. The results provide direct evidence showing how the molecular structures of the mixed layer vary and affect the PL intensity due to temperature.

Two-dimensional assemblies of banana-shaped liquid crystal molecules on HOPG surface.

Two-dimensional assemblies of a series of banana-shaped liquid crystal molecules, 1,3-phenylene bis[4-(4-n-alkylphenyliminomethyl) benzoates] (P-n-PIMB, n = 12, 14, 18), are investigated on a highly oriented pyrolytic graphite (HOPG) surface by using scanning tunneling microscopy (STM) at a submolecular level in an ambient environment. Two types of molecular arrangements are observed in these self-assemblies with different stripe widths that resulted from the organization of the alkyl chains. The polarization of the P-n-PIMB monolayers is exactly compensated by the adjacent lamellae with opposite bent direction. Furthermore, a bilayer structure is found in the assembly of P-18-PIMB molecules. In comparison with a gemini surfactant molecule, 4,4'-di[4-(octadecylmethylamino)styryl]-1,1'-pentamethylenebispyridinium dibromide (OPD), P-n-PIMB molecules appear in more complicated packing arrangements. The results in this paper demonstrate the effects of the molecular structures on the adlayer arrangement and will be helpful in fabricating two-dimensional molecular structures on solid surfaces.