A mild and efficient stereoselective synthesis of (Z)- and (E)-allyl sulfides and potent antifungal agent, (Z)-3-(4-methoxybenzylidene)thiochroman-4-one from Morita-Baylis-Hillman acetates

A facile stereoselective synthesis of (Z)- and (E)-allyl sulfides has been accomplished from Morita-Baylis-Hillman acetates in one-pot by treatment with benzene thiol in the presence of catalytic amounts of 15% aqueous NaOH and TBAI in DMSO at room temperature. The method has been applied for the synthesis of (Z)-3-(4-methoxybenzylidene)thiochroman-4-one, a potent antifungal compound.     

nDEP microwells for single-cell patterning in physiological media

We present a novel technique to accurately position single cells on a substrate using negative dielectrophoresis and cell-substrate adhesion. The cells are suspended in physiological media throughout the patterning process. We also verify the biocompatibility of this method by demonstrating that the patterned cells proliferate and show normal morphology. We calculate the temperatures and transmembrane potential that cells in the device experience and compare them to physiologically acceptable levels described in previous studies.     

Influence of stereochemistry and redox potentials on the single- and double-strand DNA cleavage efficiency of Cu(II) and Ni(II) Lys-Gly-His-derived ATCUN metallopeptides

The DNA cleavage chemistry of a series of metallopeptides based on the amino-terminal Cu and Ni (ATCUN) binding motif of proteins has been studied. Specifically, the impact of the positioning of charged Lys side chains and their stereochemistry on metal reduction potentials and DNA cleavage reactivity have been quantitatively evaluated. Both Cu and Ni metallopeptides show a general increase in reactivity toward DNA with an increasing number of Lys residues, while a corresponding decrease in complex reduction potential reflects the enhanced sigma-donor character of the Lys side chain relative to that of Gly. Placement of Lys at the first position in the tripeptide ligand sequence resulted in a greater increase in DNA cleavage reactivity, relative to placement at the second position, while a switch from an l-Lys to a d-Lys typically resulted in enhanced reactivity, as well as perturbations of reduction potential. In the case of Cu peptides, reactivity was enhanced with both increasing positive charge density on the peptide and stabilization of the Cu3+ state. However, for Ni peptides, while the general trends are the same, the correlation with redox behavior was less pronounced. Most likely these differences in specific trends for the Cu and Ni complexes reflect the distinct coordination preferences for Cu3+/2+ and Ni3+/2+ oxidation states, and the consequent distinct positioning of metal-associated reactive oxygen species, as well as the orientation of the DNA-associated complex. Thus, the amino acid composition and stereochemistry of ATCUN metallopeptides can tune the intrinsic reactivities of these systems (their ability to promote formation and activity of metal-associated ROS) as well as their overall structural features, and both of these aspects appear to influence their reactivity and efficiency of DNA strand scission.     

Destructive and protective action of sodium dodecyl sulphate micelles on the native conformation of Bovine Serum Albumin: A study by extrinsic fluorescence probe 1-hydroxy-2-naphthaldehyde

The interaction of the anionic surfactant sodium dodecyl sulphate (SDS) with water soluble protein Bovine Serum Albumin (BSA) has been investigated spectroscopically using fluorescence probe 1-hydroxy-2-naphthaldehyde (HN12). The characteristic intramolecular proton transfer fluorescence band of HN12 has been used as an efficient reporter for the study of binding of SDS with BSA. The changes of spectral properties of HN12 demonstrate that SDS plays two opposite roles in the stability of protein BSA. It acts as a stabilizer at low concentration and destabilizer at high concentration to urea-denatured BSA.     

Detection of protein molecules by surface‐enhanced Raman spectroscopy‐based immunoassay using 2–5 nm gold nanoparticle lables

Here we report the synthesis of 2–5 nm size gold nanoparticle labels for surface‐enhanced Raman Spectroscopy (SERS) based immunoassay to detect protein molecules. The Au nanoparticles were conjugated with fluorescein isothiocyanate (FITC) and goat anti‐h‐IgG (immunoglobin) and the resultant particles were used for the detection of h‐IgG. Commercially available nitrocellulose strip and silver enhancement method were used for SERS‐based immunoassays. The FITC acts as a Raman probe, and vibrational fingerprint of this molecule was used for the detection of h‐IgG in concentration ranging from 1 to 100 ng/µl. Our Raman probe is robust and small in size and has high water solubility with minimum steric effect during antigen–antibody binding. Copyright © 2007 John Wiley & Sons, Ltd.     

Pressure Injury Link to Entropy of Abdominal Temperature

This study examined the association between pressure injuries and complexity of abdominal temperature measured in residents of a nursing facility. The temperature served as a proxy measure for skin thermoregulation. Refined multiscale sample entropy and bubble entropy were used to measure the irregularity of the temperature time series measured over two days at 1-min intervals. Robust summary measures were derived for the multiscale entropies and used in predictive models for pressure injuries that were built with adaptive lasso regression and neural networks. Both types of entropies were lower in the group of participants with pressure injuries (n=11) relative to the group of non-injured participants (n=15). This was generally true at the longer temporal scales, with the effect peaking at scale τ=22 min for sample entropy and τ=23 min for bubble entropy. Predictive models for pressure injury on the basis of refined multiscale sample entropy and bubble entropy yielded 96% accuracy, outperforming predictions based on any single measure of entropy. Combining entropy measures with a widely used risk assessment score led to the best prediction accuracy. Complexity of the abdominal temperature series could therefore serve as an indicator of risk of pressure injury.     

Tunable Anticancer Activity of Furoylthiourea-Based RuII–Arene Complexes and Their Mechanism of Action

Fourteen new Ru^II–arene (p-cymene/benzene) complexes ( C1 – C14 ) have been synthesized by varying the N-terminal substituent in the furoylthiourea ligand and satisfactorily characterized by using analytical and spectroscopic techniques. Electrostatic potential maps predicted that the electronic effect of the substituents was mostly localized, with some influence seen on the labile chloride ligands. The structure–activity relationships of the Ru–p-cymene and Ru–benzene complexes showed opposite trends. All the complexes were found to be highly toxic towards IMR-32 cancer cells, with C5 (Ru–p-cymene complex containing C₆H₂(CH₃)₃ as N-terminal substituent) and C13 (Ru–benzene complex containing C₆H₄(CF₃) as N-terminal substituent) showing the highest activity among each set of complexes, and hence they were chosen for further study. These complexes showed different behavior in aqueous solutions, and were also found to catalytically oxidize glutathione. They also promoted cell death by apoptosis and cell cycle arrest. Furthermore, the complexes showed good binding ability with the receptors Pim-1 kinase and vascular endothelial growth factor receptor 2, commonly overexpressed in cancer cells.     

A discrete-time model with non-monotonic functional response and strong Allee effect in prey

In this paper, we investigate the impact of strong Allee effect on the stability of a discrete-time predator–prey model with a non-monotonic functional response. The dynamics of discrete-time predator–prey models with strong Allee effect is studied earlier. But, the mathematical investigations of predator–prey dynamics in discrete-time set up with Holling type-IV functional response and strong Allee effect in prey are lacking. The proposed model supports the coexistence of two steady states, and the mathematical features of the model are analyzed based on local stability and bifurcation theory. By considering the Allee parameter as the bifurcation parameter, we provide sufficient conditions for the flip and the Neimark–Sacker bifurcations. We observe that Allee parameter plays a significant role in the dynamics of the system.