Nonenzymatic protocol for Pseudomonas aeruginosa DNA preparation and rapid subtyping by mini pulsed-field gel electrophoresis.

The fastest protocol for Pseudomonas aeruginosa subtyping by contour clamped homogeneous electric field (CHEF) electrophoresis takes around 20 h. It includes enzymatic sample preparation, DNA restriction and fragment separation. Here, P. aeruginosa cells embedded in agarose miniplugs were lysed and deproteinized by incubating the miniplugs for 30 min in a single nonenzymatic solution. DNA molecules were digested for 2 h with 5 U of XbaI, and fragments were separated in 4.96 h by miniCHEF electrophoresis at 10 V/cm. Total time for P. aeruginosa subtyping was 8 h. Control experiments included DNA preparation by enzymatic or nonenzymatic protocols, different times of DNA restriction and comparisons of DNA separations done by miniCHEF or CHEF electrophoresis. Both methods and chambers gave similar results, but the rapid nonenzymatic method and the miniCHEF gave them in less time. Cells grown in broth or on plates were useful for nonenzymatic DNA preparation. Thirteen P. aeruginosa isolates were successfully fingerprinted using the protocol described here.     

Investigation of the Europium Emission Spectra of the Europium-Oxytetracycline Complex in the Presence of Human Low-Density Lipoproteins

Low-Density Lipoprotein (LDL), often known as “bad cholesterol” is one of the responsible to increase the risk of coronary arterial diseases. For this reason, the cholesterol present in the LDL particle has become one of the main parameters to be quantified in routine clinical diagnosis. A number of tools are available to assess LDL particles and estimate the cholesterol concentration in the blood. The most common methods to quantify the LDL in the plasma are the density gradient ultracentrifugation and nuclear magnetic resonance (NMR). However, these techniques require special equipments and can take a long time to provide the results. In this paper, we report on the increase of the Europium emission in Europium-oxytetracycline complex aqueous solutions in the presence of LDL. This increase is proportional to the LDL concentration in the solution. This phenomenum can be used to develop a method to quantify the number of LDL particles in a sample. A comparison between the performances of the oxytetracycline and the tetracycline in the complexes is also made.     

Room temperature mechanical behaviour of a Ni-Fe multilayered material with modulated grain size distribution

To gain fundamental insight into the relationship between length scales and mechanical behaviour, Ni-Fe multilayered materials with a 5-μm-layer thickness and a modulated grain size distribution have been synthesized by pulsed electrodeposition. Microstructural studies by SEM and TEM reveal the alternating growth of well-defined layers with either nano (d = 16 nm) or coarse grains (d ≥ 500 nm). Room temperature tensile tests have been performed to investigate the mechanical response and understand the underlying deformation mechanisms. Tensile test results and fractographic studies demonstrate that the overall room temperature mechanical behaviour of the multilayered material, i.e. strength and ductility, is governed primarily by the layers containing nanocrystalline grains. The measured properties have been discussed in the context of modulated grain structure of the multilayered sample and contribution of each grain size regime to the overall strength and ductility.     

Characterization of Nano-Structured Poly(D,L-lactic acid) Nonwoven Mats Obtained from Different Solutions by Electrospinning

Two different solvent mixtures, chloroform/dimethylformamide (DMF) and chloroform/ acetone, in 60/40 v/v concentrations, were used to electrospin poly(D,L-lactic acid) (PDLLA). The influence of solvent type, solution concentration, and processing conditions on the morphology and properties of the electrospun mats was studied. The nanofibers characterization was done by scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The smallest nanofibers’ diameters from both mixtures were obtained from solutions with 5 wt%/v PDLLA concentration using a 1.0 kV/cm electrical field. In general the nanofibers from the chloroform/DMF mixture had smaller diameters than the nanofibers from the chloroform/acetone mixture. However, the latter ones were porous, while the nanofibers from the chloroform/DMF mixtures were not. All the PDLLA nanofibers, independent of solvent mixture, had a very low amount of crystallinity and were composed of very small and imperfect α and β crystals.     

Analysis of therapeutic proteins and peptides using multiangle light scattering coupled to ultra high performance liquid chromatography

Analysis of the physical properties of biotherapeutic proteins is crucial throughout all the stages of their lifecycle. Herein, we used size‐exclusion ultra high performance liquid chromatography coupled to multiangle light scattering and refractive index detection systems to determine the molar mass, mass‐average molar mass, molar‐mass dispersity and hydrodynamic radius of two monoclonal antibodies (rituximab and trastuzumab), a fusion protein (etanercept), and a synthetic copolymer (glatiramer acetate) employed as models. A customized instrument configuration was set to diminish band‐broadening effects and enhance sensitivity throughout detectors. The customized configuration showed a performance improvement with respect to the high‐performance liquid chromatography standard configuration, as observed by a 3 h column conditioning and a higher resolution analysis in 20 min. Analysis of the two monoclonal antibodies showed averaged values of 148.0 kDa for mass‐average molar mass and 5.4 nm for hydrodynamic radius, whereas for etanercept these values were 124.2 kDa and 6.9 nm, respectively. Molar‐mass dispersity was 1.000 on average for these proteins. Regarding glatiramer acetate, a molar mass range from 3 to 45 kDa and a molar‐mass dispersity of 1.304 were consistent with its intrinsic peptide diversity, and its mass‐average molar mass was 10.4 kDa. Overall, this method demonstrated an accurate determination of molar mass, overcoming the difficulties of size‐exclusion chromatography.     

Optical Properties of Metacycline, Oxytetracycline and Chlortetracycline Europium Complexes in the Presence of Hydrogen Peroxide

Tetracycline possesses a great tendency to form complexes with a number of chemical species, particularly with Eu³⁺ ions. In this work we investigate the europium optical properties of three tetracyclines europium complexes: Metacycline (MTc), Oxytetracycline (OTc), and Chlortetracycline (CTc), in the presence and absence of hydrogen peroxide (HP). The results show that the emission band of EuOTc have enhancement in the presence of hydrogen peroxide. A calibration curve was shown for this complex with the best molar ratio obtained.     

Interaction between protoporphyrin IX and tryptophan silver nanoparticles

Silver nanoparticles (AgNPs) have been intensively studied for several purposes including therapeutic applications in cancer. When prepared with tryptophan and photoreduction, silver nanoparticles (TrpAgNPs) become an alternative to conventional anticancer drugs. In this study, the anticancer activity of synthesized TrpAgNPs against MCF-7 breast cancer cells was evaluated, and the inhibitory concentration (IC50) was found to be ~3.4 mg/mL. Since the protoporphyrin IX (PPIX) concentrations in tumor cells are elevate compared to normal cells, the PPIX-TrpAgNP interaction was studied to investigate if it could contribute for cell apoptosis. The investigation was performed using PPIX solution (0.9 μg/mL) with different TrpAgNP concentrations (from 0 to 13 mg/mL). PPIX was characterized by UV-Vis spectroscopy, steady-state and time-resolved fluorescence spectroscopy. The results have shown that the presence of spherical TrpAgNps with 16-nm diameter quench the PPIX fluorescence intensity. This quenching is strongly dependent on the concentration of the TrpAgNPs, and it is caused by a combination of a static and a dynamic process. The chemical binding leads to oxidation of tryptophan and formation of kynurenine, observed in the emission spectra around 470 nm. The strong reduction of the PPIX fluorescence decay lifetime with nanoparticle increasing concentration confirms the quenching processes due to charge transfer from the excited PPIX states to the resonant silver states. The present study confirms the anticancer activity of TrpAgNPs on the human breast cancer cell line (MCF-7) in vitro and indicates that PPIX-AgNP interaction could contribute with MCF-7 apoptosis.

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Graphical abstract Interaction between TrpAgNPs and PPIX

     

Superconductivity in doped polyethylene at high pressure

In this work we study the pressure-dependent phase diagram of polyethylene (H₂C)_x from 50 to 200 GPa. Low-symmetry, organic polymeric phases, that are dynamically stable and thermodynamically competitive with elemental decomposition, are reported. Electronic structure calculations reveal that the band gap of the lowest energy polymeric phase decreases from 5.5 to 4.5 eV in the 50–200 GPa range, but metalization occurs only for pressures well above 500 GPa. The possibility of metalization via doping was also investigated, observing that it can be achieved through boron substitution at carbon sites. We report a sizable electron-phonon coupling (λ ? 0.79) in this metallic phase, with an estimated superconducting transition temperature of about 35 K. However, a rather narrow domain of stability is found; most of the dopant elements render the polymeric phases unstable and induce amorphization. This suggests that doping under pressure, though presenting an alternative route to find high temperature superconductors, would be challenging to achieve experimentally.     

Chamber with modifiable inner width for performing transversal alternating field electrophoresis in variable numbers of minigels

We present a transversal alternating field electrophoresis chamber that allows modifiable inner widths to accommodate low- or high-throughput formats, with 7.8 cm opposite electrode separation and 30.4 cm electrode length. Removable slotted sheets divide the chamber into four smaller compartments, each one supporting a minigel of 3.85 cm in length and 7.1 cm in width. Replacements of slotted sheets with solid dielectric blocks with the sizes and shapes of compartments permit to occlude chamber compartments, changing from 4 to 1 the numbers of minigels per run, from 88 to 13 the maximum numbers of samples, and from 1688 to 422 mL the volume of buffer poured into the chamber. Saccharomyces cerevisiae chromosomes gave its characteristic DNA band pattern in all compartments, whereas migrations of DNA molecules are not affected by the occlusion of compartments.     

Crystal Engineering of Schiff Base Zn(II) and Cd(II) Homo- and Zn(II)M(II) (M = Mn or Cd) Heterometallic Coordination Polymers and Their Ability to Accommodate Solvent Guest Molecules

Based on solvothermal synthesis, self-assembly of the heptadentate 2,6-diacetylpyridine bis(nicotinoylhydrazone) Schiff base ligand (H₂L) and Zn(II) and/or Cd(II) salts has led to the formation of three homometallic [CdL]_n (1), {[CdL]∙0.5dmf∙H₂O}_n (2) and {[ZnL]∙0.5dmf∙1.5H₂O}_n (3), as well as two heterometallic {[Zn_0.75Cd_1.25L₂]∙dmf∙0.5H₂O}_n (4) and {[MnZnL₂]∙dmf∙3H₂O}_n coordination polymers. Compound 1 represents a 1D chain, whereas 2–5 are isostructural and isomorphous two-dimensional structures. The entire series was characterized by IR spectroscopy, thermogravimetric analysis, single-crystal X-ray diffraction and emission measurements. 2D coordination polymers accommodate water and dmf molecules in their cage-shaped interlayer spaces, which are released when the samples are heated. Thus, three solvated crystals were degassed at two temperatures and their photoluminescent and adsorption–desorption properties were recorded in order to validate this assumption. Solvent-free samples reveal an increase in volume pore, adsorption specific surface area and photoluminescence with regard to synthesized crystals.