Azaaurones as Potent Antimycobacterial Agents Active against MDR- and XDR-TB

Herein we report the screening of a small library of aurones and their isosteric counterparts, azaaurones and N-acetylazaaurones, against Mycobacterium tuberculosis. Aurones were found to be inactive at 20 μm , whereas azaaurones and N-acetylazaaurones emerged as the most potent compounds, with nine derivatives displaying MIC₉₉ values ranging from 0.4 to 2.0 μm . In addition, several N-acetylazaaurones were found to be active against multidrug-resistant (MDR) and extensively drug-resistant (XDR) clinical M. tuberculosis isolates. The antimycobacterial mechanism of action of these compounds remains to be determined; however, a preliminary mechanistic study confirmed that they do not inhibit the mycobacterial cytochrome bc1 complex. Additionally, microsomal metabolic stability and metabolite identification studies revealed that N-acetylazaaurones are deacetylated to their azaaurone counterparts. Overall, these results demonstrate that azaaurones and their N-acetyl counterparts represent a new entry in the toolbox of chemotypes capable of inhibiting M. tuberculosis growth.     

Low-cost and high-performance 3D printed YBCO superconductors

High-performance YBCO 123 (YBa₂Cu₃O_7-x) bulk superconductor samples were produced using the 3D printing paste-extrusion technique. The YBCO powder obtained after sintering a pre-mixture of Y₂O₃, BaCO₃ and CuO powders at 950 °C was used in the formulation of pastes for extrusion in a 3D freeform printer. The 3D samples printed from pastes containing the pre-mixture powders were sintered, while those produced using the YBCO powder were not. X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and Raman analysis all confirmed the YBCO phase after sintering, both in the powder and in the samples made with the pre-mixture. Scanning electron microscopy (SEM) images revealed powder grains of heterogeneous size and geometry, as well as grain aggregation, in the sintered samples. Superconducting quantum interference device (SQUID) measurements taken within a fixed magnetic range revealed that the printed pieces have a typical magnetization temperature of 92 K, reaching ?1.43 emu/g and ?1.59 emu/g respectively a zero-field-cooled magnetization (ZFC) for sintered and non-sintered printed samples.     

Development of a Topical Insulin Polymeric Nanoformulation for Skin Burn Regeneration: An Experimental Approach

Insulin is a peptide hormone with many physiological functions, besides its use in diabetes treatment. An important role of insulin is related to the wound healing process—however, insulin itself is too sensitive to the external environment requiring the protective of a nanocarrier. Polymer-based nanoparticles can protect, deliver, and retain the protein in the target area. This study aims to produce and characterize a topical treatment for wound healing consisting of insulin-loaded poly-DL-lactide/glycolide (PLGA) nanoparticles. Insulin-loaded nanoparticles present a mean size of approximately 500 nm and neutral surface charge. Spherical shaped nanoparticles are observed by scanning electron microscopy and confirmed by atomic force microscopy. SDS-PAGE and circular dichroism analysis demonstrated that insulin preserved its integrity and secondary structure after the encapsulation process. In vitro release studies suggested a controlled release profile. Safety of the formulation was confirmed using cell lines, and cell viability was concentration and time-dependent. Preliminary safety in vivo assays also revealed promising results.     

Chitosan Microspheres as Carriers for pH‐Indicating Species in Corrosion Sensing

Chitosan microspheres containing bromocresol green, cresol red, and phenolphthalein for corrosion detection, through pH change, are synthesized in order to be used in protective coatings for aluminium alloys. Microspheres containing corrosion detection species are characterized morphologically (SEM) and physico‐chemically (FTIR, TGA). Release studies (UV–vis) are performed in corrosion‐promoting conditions (pH, NaCl), and detection studies by immersion in media associated with corrosion activity while microspheres' sensing activity is evaluated visually. Electrochemical characterization of AA2024 substrates in the presence of chitosan spheres is performed to understand material performance, and a color change is observed as a result of local pH increase in cathodic areas when corrosion takes place. These findings can be correlated with the results from release studies and seem a promising approach for corrosion sensing purposes, not only because pH increase is possible to detect due to corrosion, but also because chitosan is considered an environmentally friendly material.     

Osteosarcoma Pathogenesis Leads the Way to New Target Treatments

Osteosarcoma (OS) is a rare condition with very poor prognosis in a metastatic setting. Basic research has enabled a better understanding of OS pathogenesis and the discovery of new potential therapeutic targets. Phase I and II clinical trials are already ongoing, with some promising results for these patients. This article reviews OS pathogenesis and new potential therapeutic targets.     

Two-step route polycondensation for polynaphthalimides synthesis through high molar mass soluble precursors: A kinetic study

Research of polynaphthalimides (PNI) frequently reports difficulties over synthesis and processing due to insolubility. In this work, we present a novel comprehensive study on the effects of time, temperature and catalyst on the synthesis of soluble PNI precursors—polyamic acids (PAAs)—, as well as a novel synthetic procedure for the synthesis of PNI using mild conditions. Kinetic studies concerning the monomer conversion and the degree of premature imidization were performed through proton nuclear magnetic resonance and gel permeation chromatography for temperature ranging from 25 to 100°C. High temperatures (above 60°C) entail extensive premature imidization and insolubility. The use of triethylamine also catalyzes imidization. At the optimal condition, soluble PAA precursors for PNI of 72 kDa could be obtained at 40°C in N-methyl-2-pyrrolidone solution (30 wt%) after 5 hr polymerization.     

Effects of nisin concentration on properties of gelatin film-forming solutions and their films

The addition of nisin into a gelatin matrix can change properties of the film. The aim of this work was to develop gelatin-based films containing different nisin concentrations in order to study their influence on the film's antimicrobial and physical properties and their rheological properties as a film-forming solution (FFS). The FFS was characterised by rheological assays, and the gelatin-based active films were characterised and assessed by the effects of nisin concentrations on their various properties, including antimicrobial activity. Nisin's concentration affected not only its viscoelastic properties of FFS but also its film solubility in water, film surface roughness and light barrier. The addition of nisin also slightly modified the water contact angle and the mechanical properties of the gelatin films. Finally, the films demonstrated activity against Staphylococcus aureus and Listeria monocytogenes at concentrations above 56 mg of nisin g⁻¹ of gelatin.     

Experimentelle und theoretische Betrachtungen der Methanol- und direkten DME-Synthese im Labor- und Technikums-Maßstab

Engineering of strongly exothermic heterogeneously catalyzed reactions to industrial size is challenging. Synthesis of methanol and direct dimethyl ether synthesis serve as example for such type of reactions and related experimental results are described. Results from laboratory as well as technical scale are provided. The experiments show the variation of two main operational parameters: reaction temperature and CO₂ content at reactor inlet.