A highly modular and convergent approach for the synthesis of stimulant-responsive heteroligated cofacial porphyrin tweezer complexes

The synthesis of new hemilabile phosphine ligands and their reaction with [Rh(COE)2Cl]2 to form dissymmetric heteroligated tweezer complexes using a halide-induced ligand rearrangement reaction are reported. These complexes can undergo reactions with small-molecule ligands and elemental anions quantitatively in situ, which serve to regulate the porphyrin-porphyrin distances and interactions within the assembly.     

Spontaneous "phase separation" of patterned binary alkanethiol mixtures

This article describes novel phase-separation behavior by a binary mixture of alkanethiols when deposited onto a gold surface using micro- and nanodeposition tools, such as microcontact printing (muCP) and dip-pen nanolithography (DPN). This behavior is significantly different than that observed in the bulk. We demonstrate this behavior using three model compounds: 16-mercaptohexadecanoic acid (MHA), 1-octadecanethiol (ODT), and CF3(CF2)11(CH2)2SH (PFT). The identity of the resulting segregated structure is confirmed by lateral force microscopy (LFM) and by selective metal-organic coordination chemistry. Importantly, this phenomenon can be exploited to print sub-100 nm wide alkanethiol lines via conventional muCP and to form sub-15 nm features using DPN, which is below the ultimate resolution of both these techniques. We also demonstrate that these nano-patterned materials can serve as templates for constructing more complex architectures.     

Scanning electrochemical microscopy of living cells: Part 2. Imaging redox and acid/basic reactivities

Amperometric feedback and potentiometric modes of the scanning electrochemical microscope (SECM) have been used to image the topography and map redox and acid–base activities in single mammalian cells. The topographic images of cells were obtained using hydrophilic redox mediators, which cannot penetrate the cell membrane. In contrast, with a hydrophobic mediator one can map redox reactivity with a micrometer or submicrometer spatial resolution. The images obtained with oxygen used as a redox mediator show the distribution of the diffusion rate of oxygen in the cell membrane and inside the cell. The acid release by the cell was imaged with a Sb tip in a potentiometric mode, and the possibility of redox and pH imaging of the same cell with same tip is demonstrated. Significant differences were detected in the redox and pH images of normal human breast epithelial cells and metastatic breast cancer cells.     

Similarity clustering of proteins using substantive knowledge and reconstruction of evolutionary gene histories in herpesvirus

The issue of clustering proteins into homologous protein families (HPFs) has attracted considerable attention by researchers. On one side, many databases of protein families have been developed by using popular sequence alignment tools and relatively simple clustering methods followed by extensive manual curation. On the other side, more elaborate clustering approaches have been used, yet with a very limited degree of success. This paper advocates an approach to clustering protein families involving knowledge of the protein functions to adjust the parameter of similarity scale shift. One more source of external information is utilised as we proceed to reconstruct HPF evolutionary histories over an evolutionary tree; the consistency between these histories and information on gene arrangement in the genomes is used to narrow down the choice of the clustering.