Mass‐Spectrometric Observation of Counter Anion Production in SU‐8 Exposed to UV Light and its Use for Dill C Parameter Determination

Photopolymerization is a phenomenon that is the basis of much of today's microfabrication technology and intense research is conducted to improve its control and the characteristics of end products for a variety of applications. The design of microscopic structures often relies on the accurate knowledge and modeling of photopolymer's behavior upon exposure, i.e. the Dill parameters, for each radiation species of interest and therefore the development of flexible characterization techniques is of great importance. SU‐8 is a popular compound that is representative of a whole class that relies on cationic polymerization, where an acid is obtained via photolysis of an onium salt during exposure. Here we report on the observation of SbF₆^? via laser desorption mass spectrometry on SU‐8 exposed to UV light at the wavelength of 365 nm and demonstrate that the yield of this counter‐anion as a function of exposure is consistent with the Dill C parameter value available in the literature. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 967–972     

Nitrogen Doping and Carbon Coating Affects Substrate Selectivity of TiO2 Photocatalytic Organic Pollutant Degradation

A series of carbon-coated, nitrogen-doped titanium dioxide photocatalysts was produced and characterized. N-doped TiO₂ powder samples were prepared using a sol-gel method and subsequently used for making doped-TiO₂ thin films on glass substrates. Carbon layers were coated on the films by a thermal decomposition method using catechol. Diffuse reflectance spectra and Mott-Schottky analyses of the samples proved that nitrogen doping and carbon coating can slightly lower the band gap of TiO₂, broaden its absorption to visible light and enhance its n-type character. According to photocatalytic tests against model contaminants, carbon-coated nitrogen-doped TiO₂ films have better performance than simple TiO₂ on the degradation of Rhodamine B dye molecules, but are poorly effective for degrading 4-chlorophenol molecules. Several possible explanations are proposed for this result, supported by scavenging experiments. This reveals the importance of a broad substrate scope when assessing new photocatalytic materials for water treatment, something which is often overlooked in many literature studies.     

Female Faculty: Why So Few and Why Care?

Despite slow ongoing progress in increasing the representation of women in academia, women remain significantly under-represented at senior levels, in particular in the natural sciences and engineering. Not infrequently, this is downplayed by bringing forth arguments such as inherent biological differences between genders, that current policies are adequate to address the issue, or by deflecting this as being “not my problem” among other examples. In this piece we present scientific evidence that counters these claims, as well as a best-practice example, Genie, from Chalmers University of Technology, where one of the authors is currently employed. We also highlight particular challenges caused by the current COVID-19 pandemic. Finally, we conclude by proposing some possible solutions to the situation and emphasize that we need to all do our part, to ensure that the next generation of academics experience a more diverse, inclusive, and equitable working environment.     

Chemoselective Hydrogenation of 6-Alkynyl-3-fluoro-2-pyridinaldoximes: Access to First-in-Class 6-Alkyl-3-Fluoro-2-pyridinaldoxime Scaffolds as New Reactivators of Sarin-Inhibited Human Acetylcholinesterase with Increased Blood–Brain Barrier Permeability

Novel 6-alkyl- and 6-alkenyl-3-fluoro-2-pyridinaldoximes have been synthesised by using a mild and efficient chemoselective hydrogenation of 6-alkynyl-3-fluoro-2-pyridinaldoxime scaffolds, without altering the reducible, unprotected, sensitive oxime functionality and the C−F bond. These novel 6-alkyl-3-fluoro-2-pyridinaldoximes may find medicinal application as antidotes to organophosphate poisoning. Indeed, one low-molecular-weight compound exhibited increased affinity for sarin-inhibited acetylcholinesterase (hAChE) and greater reactivation efficiency or resurrection for sarin-inhibited hAChE, compared with those of 2-pyridinaldoxime (2-PAM) and 1-({[4-(aminocarbonyl)pyridinio]methoxy}methyl)-2-[(hydroxyimino)methyl]pyridinium chloride (HI-6), two pyridinium salts currently used as antidote by several countries. In addition, the uncharged 3-fluorinated bifunctional hybrid showed increased in vitro blood–brain barrier permeability compared with those of 2-PAM, HI-6 and obidoxime. These promising features of novel low-molecular-weight alkylfluoropyridinaldoxime open up a new era for the design, synthesis and discovery of central non-quaternary broad spectrum reactivators for organophosphate-inhibited cholinesterases.     

Comparison of RAFT‐derived poly(vinylpyrrolidone) verses poly(oligoethyleneglycol methacrylate) for the stabilization of glycosylated gold nanoparticles

Carbohydrates dictate many biological processes including infection by pathogens. Glycosylated polymers and nanomaterials which have increased affinity due to the cluster glycoside effect, are therefore useful tools to probe function, but also as prophylactic therapies or diagnostic tools. Here, the effect of polymer structure on the coating of gold nanoparticles is studied in the context of grafting density, buffer stability, and in a lectin binding assay. RAFT polymerization is used to generate poly(oligoethyleneglycol methacrylates) and poly(N‐vinylpyrrolidones) with a thiol end‐group for subsequent immobilization onto the gold. It is observed that poly(oligoethylene glycol methacrylates), despite being widely used particle coatings, lead to low grafting densities which in turn resulted in lower stability in biological buffers. A depression of the cloud point upon nanoparticle immobilization is also seen, which might compromise performance. In comparison poly(vinylpyrrolidones) resulted in stable particles with higher grafting densities due to the compact size of each monomer unit. The higher grafting density also enabled an increase in the number of carbohydrates which can be installed per nanoparticle at the chain ends, and gave increased binding in a lectin recognition assay. These results will guide the development of new nanoparticle biosensors with enhanced specificity, affinity, and stability. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1200–1208     

Hydrodechlorination of Dichloromethane by a Metal-Free Triazole-Porphyrin Electrocatalyst: Demonstration of Main-Group Element Electrocatalysis**

In this work, the electrocatalytic reduction of dichloromethane (CH₂Cl₂) into hydrocarbons involving a main group element-based molecular triazole-porphyrin electrocatalyst H2PorT8 is reported. This catalyst converted CH₂Cl₂ in acetonitrile to various hydrocarbons (methane, ethane, and ethylene) with a Faradaic efficiency of 70 % and current density of −13 mA cm⁻² at a potential of −2.2 V vs. Fc/Fc⁺ using water as a proton source. The findings of this study and its mechanistic interpretations demonstrated that H2PorT8 was an efficient and stable catalyst for the hydrodechlorination of CH₂Cl₂ and that main group catalysts could be potentially used for exploring new catalytic reaction mechanisms.     

Binding of Dopamine to Alpha-Synuclein is Mediated by Specific Conformational States

Parkinson’s disease is the second most common neurodegenerative disorder, in which both alpha-synuclein (α-syn) and dopamine (DA) have a critical role. α-Syn is known to be natively unstructured in equilibrium with subpopulations of more compact structures. It is these compact structures that are thought to be linked to amyloid formation. In the presence of DA, α-syn yields a diverse range of SDS-resistant, non-amyloid oligomers, however the precursor state conformation has not been established. Here, three DA molecules have been observed to bind per α-syn monomer by electrospray-ionization-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS). Each of these DA molecules binds exclusively to the extended conformation of α-syn, and binding is not observed in the compact state of the protein. Measurements of collisional cross sectional areas show that the incremental uptake of DA pushes the protein towards a highly extended population, becoming fully populated upon the binding of three DA ligands. Tyrosine (Tyr) as a closely related structural analog, exhibited limited binding to the protein as compared with DA, with a maximum of two ligands being observed. Those Tyr ligands that do bind were observed as adducts to the extended conformation akin to DA. These findings suggest DA is able to modulate α-syn self-assembly by inducing the population of a highly extended state.

PCR-based detection of gene transfer vectors: application to gene doping surveillance

Athletes who illicitly use drugs to enhance their athletic performance are at risk of being banned from sports competitions. Consequently, some athletes may seek new doping methods that they expect to be capable of circumventing detection. With advances in gene transfer vector design and therapeutic gene transfer, and demonstrations of safety and therapeutic benefit in humans, there is an increased probability of the pursuit of gene doping by athletes. In anticipation of the potential for gene doping, assays have been established to directly detect complementary DNA of genes that are top candidates for use in doping, as well as vector control elements. The development of molecular assays that are capable of exposing gene doping in sports can serve as a deterrent and may also identify athletes who have illicitly used gene transfer for performance enhancement. PCR-based methods to detect foreign DNA with high reliability, sensitivity, and specificity include TaqMan real-time PCR, nested PCR, and internal threshold control PCR.