Advances in electroanalysis, sensing and monitoring in molten salts.

Microelectrodes have a number of advantages over macroelectrodes for quantitative electroanalysis and monitoring, including reduced iR drop, a high signal-to-noise ratio and reduced sensitivity to convection. Their use in molten salts has been generally precluded by the combined materials challenges of stresses associated with thermal cycling and physical and corrosive chemical degradation at the relatively high temperatures involved. We have shown that microfabrication, employing high precision photolithographic patterning in combination with the controlled deposition of materials, can be used to successfully address these challenges. The resulting molten salt compatible microelectrodes (MSMs) enable prolonged quantitative microelectrode measurements in molten salts (MSs). This paper reports the fabrication of novel MSM disc electrodes, chosen because they have an established ambient analytical response. It includes a detailed set of electrochemical characterisation studies which demonstrate both their enhanced capability over macroelectrodes and over commercial glass pulled microelectrodes, and their ability to extract quantitative electroanalytical information from MS systems. MSM measurements are then used to demonstrate their potential for shedding new light on the fundamental properties of, and processes in, MSs, such as mass transport, charge transfer reaction rates and the selective plating/stripping and alloying reactions of liquid Bi and other metals; this will underpin the development of enhanced MS industrial processes, including pyrochemical spent nuclear fuel reprocessing.

Structure of the unique tetrameric STENOFOLIA homeodomain bound with target promoter DNA.

Homeobox transcription factors are key regulators of morphogenesis and development in both animals and plants. In plants, the WUSCHEL-related homeobox (WOX) family of transcription factors function as central organizers of several developmental programs ranging from embryo patterning to meristematic stem-cell maintenance through transcriptional activation and repression mechanisms. The Medicago truncatula STENOFOLIA (STF) gene is a master regulator of leaf-blade lateral development. Here, the crystal structure of the homeodomain (HD) of STF (STF-HD) in complex with its promoter DNA is reported at 2.1 Šresolution. STF-HD binds DNA as a tetramer, enclosing nearly the entire bound DNA surface. The STF-HD tetramer is partially stabilized by docking of the C-terminal tail of one protomer onto a conserved hydrophobic surface on the head of another protomer in a head-to-tail manner. STF-HD specifically binds TGA motifs, although the promoter sequence also contains TAAT motifs. Helix α3 not only serves a canonical role as a base reader in the major groove, but also provides DNA binding in the minor groove through basic residues located at its C-terminus. The structural and functional data in planta reported here provide new insights into the DNA-binding mechanisms of plant-specific HDs from the WOX family of transcription factors.

Optimization of a Collagen-Targeted PET Probe for Molecular Imaging of Pulmonary Fibrosis.

There is a large unmet need for a simple, accurate, noninvasive, quantitative, and high-resolution imaging modality to detect lung fibrosis at early stage and to monitor disease progression. Overexpression of collagen is a hallmark of organ fibrosis. Here, we describe the optimization of a collagen-targeted PET probe for staging pulmonary fibrosis. Methods: Six peptides were synthesized, conjugated to a copper chelator, and radiolabeled with 64Cu. The collagen affinity of each probe was measured in a plate-based assay. The pharmacokinetics and metabolic stability of the probes were studied in healthy rats. The capacity of these probes to detect and stage pulmonary fibrosis in vivo was assessed in a mouse model of bleomycin-induced fibrosis using PET imaging. Results: All probes exhibited affinities in the low micromolar range (1.6 µM < Kd < 14.6 µM) and had rapid blood clearance. The probes showed 2- to 8-fold-greater uptake in the lungs of bleomycin-treated mice than sham-treated mice, whereas the distribution in other organs was similar between bleomycin-treated and sham mice. The probe 64Cu-CBP7 showed the highest uptake in fibrotic lungs and the highest target-to-background ratios. The superiority of 64Cu-CBP7 was traced to a much higher metabolic stability compared with the other probes. The specificity of 64Cu-CBP7 for collagen was confirmed by comparison with a nonbinding isomer. Conclusion:64Cu-CBP7 is a promising candidate for in vivo imaging of pulmonary fibrosis.

Molecular imaging of oxidized collagen quantifies pulmonary and hepatic fibrogenesis.

Fibrosis results from the dysregulation of tissue repair mechanisms affecting major organ systems, leading to chronic extracellular matrix buildup, and progressive, often fatal, organ failure. Current diagnosis relies on invasive biopsies. Noninvasive methods today cannot distinguish actively progressive fibrogenesis from stable scar, and thus are insensitive for monitoring disease activity or therapeutic responses. Collagen oxidation is a universal signature of active fibrogenesis that precedes collagen crosslinking. Biochemically targeting oxidized lysine residues formed by the action of lysyl oxidase on collagen with a small-molecule gadolinium chelate enables targeted molecular magnetic resonance imaging. This noninvasive direct biochemical elucidation of the fibrotic microenvironment specifically and robustly detected and staged pulmonary and hepatic fibrosis progression, and monitored therapeutic response in animal models. Furthermore, this paradigm is translatable and generally applicable to diverse fibroproliferative disorders.