Effect of the graft ratio on the properties of polythiophene‐g‐poly(ethylene glycol)

Graft copolymers formed by anchoring poly(ethylene glycol) (PEG) chains to conjugated polythiophene have been prepared by copolymerizing two compounds: unsubstituted α‐terthiophene (Th₃) and a thiophene‐derived macromonomer having an α‐terthiophene conjugated sequence and one Th₃ bearing a PEG chain with molecular weight of 2000 as substitute at the 3‐position of the central heterocycle (Th₃‐PEG₂₀₀₀). The grafting ratio of the resulting copolymers (PTh₃^*‐g‐PEG), which were obtained using 75:25 and 50:50 Th₃‐PEG₂₀₀₀:Th₃ weight ratios, is significantly smaller than that of copolymers derived from polymerization of macromonomers consisting of a α‐pentathiophene sequence in which the central ring bears a PEG chain of M_w = 2000 (PTh₅‐g‐PEG). The electroactivity and electrochemical stability of PTh₃^*‐g‐PEG is not only higher than that of PTh₅‐g‐PEG but also higher than that of PTh₃, the latter presenting a very compact structure that makes difficult the access and escape of dopant ions into the polymeric matrix during the redox processes. Furthermore, the optical π‐π^* lowest transition energy of PTh₃^*‐g‐PEG is lower than that of both PTh₅‐g‐PEG and PTh₃. These properties, combined with suitable wettability and roughness, result in an excellent behavior as bioactive platform of PTh₃^*‐g‐PEG copolymers, which are more biocompatible, in terms of cellular adhesion and proliferation, and electro‐compatible than PTh₅‐g‐PEG. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 239–252     

Environmental application of pulsed laser-induced incandescence

A portable instrument based on two-color laser-induced incandescence (LII) technique has been designed and developed for the detection of carbonaceous particles for environmental applications. The instrument has been calibrated by performing LII measurements at the exhaust of a home-made soot generator. The incandescence signal from particles sampled into the instrument has been compared with in situ, calibrated, LII measurements to correlate the incandescence signal by the instrument with particles concentration. Measurements of particulate with the LII instrument were then conducted in different environmental conditions, covering a wide range of concentration (from ambient air to cars’ exhaust). The detection limit of the LII instrument has been estimated to be in the range of 200 ng/m³. These measurements have been also compared with results obtained with a commercial aethalometer. The results show a linear relationship between the two sets of measurements, also in the case where significant variation of the carbon particles concentration has been observed over time. These observations allow us to infer that the two instruments are responding in the same way to different carbon particles load, size and nature.     

Isothermal pressure dependence of the solubility of some triazines in supercritical CO2

 The solubility of two related series of each three triazine compounds has been determined in supercritical CO₂, at 40 °C and pressures between 80 and 220⋅10⁵ Pa. A high pressure small volume cell with adjustable optical path and built-in circulation pump has been constructed to be used with quartz windows in a Perkin Elmer UV-VIS spectral photometer. At 220 bar solubilities are between 0.3 and 25 g/L, dependent on the specific triazine structure. The isothermal pressure dependence of the solubility could be modelled using the pressure dependent dielectric constant of CO₂ as the only variable. Received: 30 October 1996/Revised: 3 April 1997/Accepted: 13 April 1997     

Light‐mediated DNA Repair Prevents UVB‐induced Cell Cycle Arrest in Embryos of the Crustacean Macrobrachium olfersi

High levels of ultraviolet‐B (UVB) radiation can negatively affect aquatic animals. Macrobrachium olfersi is a prawn that lives in clear freshwaters and during the breeding season, females carry eggs in an external brood pouch. Therefore, we hypothesize that eggs are also exposed to environmental UVB radiation. The aim of this study was to investigate whether UVB radiation induces DNA damage and compromises cell cycle in embryos of M. olfersi. In laboratory, UVB irradiance (310 mW. cm^?2) that embryos receive in the natural environment was simulated. After irradiation, embryos were kept under different light conditions in order to recognize the presence of cell repair. UVB radiation induces DNA damage, specifically thymine dimers. After 48 h of UVB exposure, a significant decrease in the level of these dimers was observed in embryos kept under visible light while it remained constant in the dark. Moreover, under visible light and darkness, a decrease in proliferation was observed after 48 h of irradiation. An increase in PCNA expression and decrease in p53 expression were observed after, respectively, 1 and 48 h of exposure. Our results showed that UVB radiation disturbs the cell cycle and induces DNA damage in M. olfersi embryos. However, under visible light these embryos showed successful DNA repair.     

Characterisation of captopril photolysis and photocatalysis by-products in water by direct infusion,electrospray ionisation,high-resolution mass spectrometry and the assessment of their toxicities

Pharmaceuticals of different therapeutic classes are found in the environment. Captopril is used worldwide as an antihypertensive drug, and it has been found in the influent, effluent and secondary sludge of wastewater treatment plants. Advanced oxidation processes, such as direct photolysis (UV-C) and heterogeneous photocatalysis (TiO₂/UV-C), are alternatives to enhance mineralisation of pharmaceuticals and their removal during water treatment. In this article, it was evaluated the degradation of captopril in aqueous solution induced by UV-C and TiO₂/UV-C systems. The process focused on the identification and monitoring of the by-products formed under these conditions by applying direct-infusion electrospray ionisation high-resolution mass spectrometry in the negative ion mode (ESI(-)-HRMS) and high-performance liquid chromatography coupled to high-resolution mass spectrometry (HPLC/HRMS). To evaluate the by-products toxicity, acute ecotoxicity tests were performed with the crustacean Artemia salina, and the cytotoxicity was evaluated with (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using HepG2 cells. It was observed by ESI(-)-HRMS that after 120 min of light exposure, there was almost complete removal of captopril, with 93.5% removal efficiency during photolysis and 99.9% during photocatalysis. At these conditions, the rate of mineralisation, by total organic carbon (TOC), was only 2.92% for photolysis and 9.09% for photocatalysis, evidencing the formation of degradation by-products. Nine by-products of captopril photodegradation were identified, and their respective chemical structure elucidations were proposed. The treated samples were nontoxic to A. salina and HepG2 cells, indicating that both oxidative treatments (photocatalytic or photolytic processes) can be conveniently employed to remove captopril from aqueous media.     

Advances in electrochemical detection for probing protein aggregation

Electrochemistry provides an array of methods to investigate protein aggregation and determine biomarkers of neurodenenerative diseases. Biosensors detecting monomeric or oligomeric biomarkers of Alzheimer's disease and Parkinson's disease evolved toward femtomolar, multiplexed detection in blood and biological fluids for less invasive diagnosis. The biosensors also serve as complementary tools in studies investigating putative biomarkers for the assessment of patient's cognitive decline. The study of protein aggregation via the direct electrochemical oxidation focused recently on enhanced sensitivity and on establishing correlations between protein structure and aggregation propensity. Departing from classic approaches, nanopore resistive pulse sensing and single-particle collision electrochemistry enable studying aggregates in solution. Growing applications converge toward accurate evaluation of aggregate populations and method adoption beyond proof of principle.     

Pharmacological Insights into Halophyte Bioactive Extract Action on Anti-Inflammatory,Pain Relief and Antibiotics-Type Mechanisms

The pharmacological activities in bioactive plant extracts play an increasing role in sustainable resources for valorization and biomedical applications. Bioactive phytochemicals, including natural compounds, secondary metabolites and their derivatives, have attracted significant attention for use in both medicinal products and cosmetic products. Our review highlights the pharmacological mode-of-action and current biomedical applications of key bioactive compounds applied as anti-inflammatory, bactericidal with antibiotics effects, and pain relief purposes in controlled clinical studies or preclinical studies. In this systematic review, the availability of bioactive compounds from several salt-tolerant plant species, mainly focusing on the three promising species Aster tripolium, Crithmum maritimum and Salicornia europaea, are summarized and discussed. All three of them have been widely used in natural folk medicines and are now in the focus for future nutraceutical and pharmacological applications.     

Impact of Covalent Modifications on the Hydrogen Bond Strengths in Diaminotriazine Supramolecules

Melamine (M) is a popular triamine triazine compound in the field of supramolecular materials. In this work, we have computationally investigated how substituents can be exploited to improve the binding strength of M supramolecules. Two types of covalent modifications were studied: the substitution of an H atom within an amine group −NHR, and the replacement of the whole −NH₂ group (R=H, F, CH₃ and COCH₃). Through our dispersion-corrected density functional theory computations, we explain which covalent modification will show the best self-assembling capabilities, and why the binding energy is enhanced. Our charge density and molecular orbital analyses indicate that the best substituents are those that generate a charge accumulation on the endocyclic N atom, providing an improvement of the electrostatic attraction. At the same time the substituent assists the main N−H⋅⋅⋅N hydrogen bonds by interacting with the amino group of the other monomer. We also show how the selected group notably boosts the strength of hexameric rosettes. This research, therefore, provides molecular tools for the rational design of emerging materials based on uneven hydrogen-bonded arrangements.     

Monitoring of visible light photopolymerization of an epoxy/dimethacrylate hybrid system by Raman and near-infrared spectroscopies

Hybrid systems formulated with epoxy and methacrylate monomers at mass fraction either 50:50 or 75:25 were studied. The individual monomer conversions during photopolymerization with visible light were monitored by Raman and near-infrared spectroscopies. The rate of polymerization and final degree of conversion of the methacrylate groups were raised when the epoxy monomer was present. This is attributed to enhancement of the mobility of the reactive species caused by the presence of the epoxy monomer. Conversely, the earlier vitrification of the system due to the faster polymerizing methacrylate network resulted in reduced conversion of epoxy rings.