Multi-detection method for five common microalgal toxins based on the use of microspheres coupled to a flow-cytometry system

Freshwater and brackish microalgal toxins, such as microcystins, cylindrospermopsins, paralytic toxins, anatoxins or other neurotoxins are produced during the overgrowth of certain phytoplankton and benthic cyanobacteria, which includes either prokaryotic or eukaryotic microalgae. Although, further studies are necessary to define the biological role of these toxins, at least some of them are known to be poisonous to humans and wildlife due to their occurrence in these aquatic systems. The World Health Organization (WHO) has established as provisional recommended limit 1 μg of microcystin-LR per liter of drinking water. In this work we present a microsphere-based multi-detection method for five classes of freshwater and brackish toxins: microcystin-LR (MC-LR), cylindrospermopsin (CYN), anatoxin-a (ANA-a), saxitoxin (STX) and domoic acid (DA). Five inhibition assays were developed using different binding proteins and microsphere classes coupled to a flow-cytometry Luminex system. Then, assays were combined in one method for the simultaneous detection of the toxins. The IC₅₀'s using this method were 1.9 ± 0.1 μg L⁻¹ MC-LR, 1.3 ± 0.1 μg L⁻¹ CYN, 61 ± 4 μg L⁻¹ ANA-a, 5.4 ± 0.4 μg L⁻¹ STX and 4.9 ± 0.9 μg L⁻¹ DA. Lyophilized cyanobacterial culture samples were extracted using a simple procedure and analyzed by the Luminex method and by UPLC–IT-TOF-MS. Similar quantification was obtained by both methods for all toxins except for ANA-a, whereby the estimated content was lower when using UPLC–IT-TOF-MS. Therefore, this newly developed multiplexed detection method provides a rapid, simple, semi-quantitative screening tool for the simultaneous detection of five environmentally important freshwater and brackish toxins, in buffer and cyanobacterial extracts.     

Solubility of Argon and Nitrogen in Aqueous Solutions of Dodecyltrimethylammonium Bromide (DTAB) from 283.15 to 298.15 K and 101325 Pa Partial Pressure of Gas

The solubility of nitrogen and argon in aqueous solutions of dodecyltrimethylammonium bromide (DTAB) were measured, using the drop pressure method, at temperatures between (283.15 and 298.15) K and partial pressure of 101325 Pa of gas in an instrument specially developed for this purpose. The gas solubility was calculated as Henry’s constant. The solubilities of argon and of nitrogen increase linearly with DTAB concentration and decrease as the temperature increases. Experimental results show that the increase in the solubility of argon and nitrogen in the DTAB micelles is between 59.0 and 83.5 higher than the solubility in pure water, reflecting the ability of DTAB micelles to increase the solubility of non-polar gases in water.     

Preparative treatment with NaOH to selectively concentrate iron oxides of a Chilean volcanic soil?material to produce effective heterogeneous Fenton catalyst

A Chilean volcanic Ultisol material was first size-fractionated so as to obtain the fraction with mean particle sizes ??<?53 ??m. This sample was then sequentially treated three or five times with 5 mol L^???1 NaOH, in an attempt to evaluate the effectiveness of the selective chemical dissolution to concentrate iron oxides, as a preparation procedure before using the materials as heterogeneous Fenton catalysts. The effects of those treatments on the iron oxides mineralogy were monitored with Mössbauer spectroscopy. The NaOH-treated samples were tested as catalysts towards the H₂O₂ decomposition. Three or five sequential NaOH treatments were found to be comparably effective, by concentrating nearly the same proportion of iron oxides in the remaining solid phase (25.1 ± 0.4 and 23.3 ± 0.2 mass%, respectively). 298 K-Mössbauer patterns were similar for both samples, with a central (super)paramagnetic Fe^3?+? doublet and a broad sextet, assignable to several closely coexisting magnetically ordered forms of iron oxides. Despite of this nearly similar effect of the two treatments, the Ultisol material treated three times with NaOH presents higher heterogeneous catalytic efficiency and is more suitable to decompose H₂O₂ than that with five treatments.     

Self‐Assembling Supramolecular Hybrid Hydrogel Beads

With the goal of imposing shape and structure on supramolecular gels, we combine a low‐molecular‐weight gelator (LMWG) with the polymer gelator (PG) calcium alginate in a hybrid hydrogel. By imposing thermal and temporal control of the orthogonal gelation methods, the system either forms an extended interpenetrating network or core–shell‐structured gel beads—a rare example of a supramolecular gel formulated inside discrete gel spheres. The self‐assembled LMWG retains its unique properties within the beads, such as remediating Pd^II and reducing it in situ to yield catalytically active Pd⁰ nanoparticles. A single PdNP‐loaded gel bead can catalyse the Suzuki–Miyaura reaction, constituting a simple and easy‐to‐use reaction‐dosing form. These uniquely shaped and structured LMWG‐filled gel beads are a versatile platform technology with great potential in a range of applications.     

Single‐Crystal X‐Ray Diffraction Study of Pressure and Temperature‐Induced Spin Trapping in a Bistable Iron(II) Hofmann Framework

High‐pressure single‐crystal X‐ray diffraction has been used to trap both the low‐spin (LS) and high‐spin (HS) states of the iron(II) Hofmann spin crossover framework, [Fe^II(pdm)(H₂O)[Ag(CN)₂]₂?H₂O, under identical experimental conditions, allowing the structural changes arising from the spin‐transition to be deconvoluted from previously reported thermal effects.     

On the Use of Metal Purine Derivatives (M=Ir,Rh) for the Selective Labeling of Nucleosides and Nucleotides

The reactions of neutral or cationic Ir^III and Rh^III derivatives of phenyl purine nucleobases with unsymmetrical alkynes produce new metallacycles in a predictable manner, which allows for the incorporation of either photoactive (anthracene or pyrene) or electroactive (ferrocene) labels in the nucleotide or nucleoside moiety. The reported methodology (metalation of the purine derivative and subsequent marker insertion) could be used for the postfunctionalization and unambiguous labeling of oligonucleotides.     

Wound debridement and antibiofilm properties of gamma-ray DMAEMA-grafted onto cotton gauzes

Cotton gauze fabric was functionalized with 2-(dimethylamino)ethyl methacrylate (DMAEMA) with the aim of developing wound dressings with antibiofilm activity and tunable debriding activity. Cotton-g-DMAEMA gauzes were prepared via one-step grafting (direct method) using ⁶⁰Co γ-rays as source to initiate the polymerization process. The effects of absorbed dose, dose rate, and monomer concentration on the degree of grafting were evaluated in detail. Some cotton-g-DMAEMA gauzes were subsequently quaternized with methyl iodide. Grafting of DMAEMA and sequential quaternization were confirmed by FTIR-ATR spectroscopy; thermal properties were analyzed using TGA, and morphology by scanning electron microscopy. Grafting of DMAEMA gauzes enhanced blood absorption and collagenase activity, while further quaternization led to a remarkable inhibition of the proteinase activity. Their antimicrobial features were analyzed by evaluating their biofilm inhibiting and biofilm eradicating properties in an in vitro chronic wound model. Although the non-quaternized gauzes only displayed moderate biofilm inhibitory properties at best, the quaternized cotton-g-DMAEMA bearing the highest content of DMAEMA displayed strong biofilm inhibiting and biofilm eradicating properties. This indicates that quaternized cotton-g-DMAEMA gauzes are less prone to be colonized by bacteria and can notably reduce the number of colonies in an infected wound.     

Topical caffeine delivery using biocellulose membranes: a potential innovative system for cellulite treatment

In this study, biocellulose (BC) membranes have been investigated as caffeine topical delivery systems, for the potential treatment of cellulite. BC-caffeine membranes were prepared by a simple approach and the permeation of caffeine through human epidermis, from BC or from conventional formulation systems (solution and gel), was compared in vitro to assess their therapeutic applicability. Diffusion studies with Franz cells showed that the incorporation of caffeine in BC membranes provided lower permeation rates than those obtained with the conventional formulations. These results combined with the possibility of producing BC membranes with different shapes demonstrate that these materials are promising biosystems for topical delivery of caffeine, showing reproducibility and an extended and predictable caffeine release over time, leading to their potential use for cellulite attenuation.     

Effect of the Instant Controlled Pressure Drop Technology in Cardamom (Elettaria cardamomum) Essential Oil Extraction and Antioxidant Activity

Green cardamom (Elettaria cardamomum) is an outspread spice native to Asia, which is well appreciated for its sensory characteristics, delicate aroma, and unique taste. Currently, the main cardamom extracts are essential oils (EOs), and regarding current market tendencies, this market is in high growth. For this reason, technologies such as the instant controlled pressure drop (DIC) have been applied to reach higher yields and better quality of EO. Then, this study explores the impact of DIC as a pretreatment before hydrodistillation (HD) on the EO yield and their antioxidant activity. Obtained results showed that the coupling of DIC-HD increased the yield of essential oil and also had a positive impact on their antioxidant capacity. The EO yield of DIC-HD (140 °C and 30 s) was 4.43% vs. 2.52% for control; the AOX of DIC-HD (165 °C and 30 s) was 86% inhibition vs. 57.02% for control, and the TEAC of DIC-HD (140 °C and 30 s) was 1.44 uMTE/g EO vs. 13.66 uMTE/g EO.     

Dynamic Covalent Properties of a Novel Indolo[3,2-b]carbazole Diradical

This work describes the synthesis and properties of a dicyanomethylene-substituted indolo[3,2-b]carbazole diradical ICz-CN. This quinoidal system dimerises almost completely to (ICz-CN)₂, which contains two long C(sp³)−C(sp³) σ-bonds between the dicyanomethylene units. The minor open-shell ICz-CN component in the solid-state mixture was identified by EPR spectroscopy. Cyclic voltammetry and UV–visible spectroelectrochemical data, as well as comparison with reference monomer ICz-Br reveal that the nature of the one-electron oxidation of (ICz-CN)₂ at ambient temperature and ICz-CN at elevated temperature is very similar in all these compounds due to the prevailing localization of their HOMO on the ICz backbone. The peculiar cathodic behaviour reflects the co-existence of (ICz-CN)₂ and ICz-CN. The involvement of the dicyanomethylene groups stabilizes the close-lying LUMO and LUMO+1 of (ICz-CN)₂ and especially ICz-CN compared to ICz-Br, resulting in a distinctive cathodic response at low overpotentials. Differently from neutral ICz-CN, its radical anion and dianion are remarkably stable under ambient conditions. The UV/Vis(–NIR) electronic transitions in parent (ICz-CN)₂ and ICz-CN and their different redox forms have been assigned convincingly with the aid of TD-DFT calculations. The σ-bond in neutral (ICz-CN)₂ is cleaved in solution and in the solid-state upon soft external stimuli (temperature, pressure), showing a strong chromism from light yellow to blue–green. Notably, in the solid state, the monomeric diradical species is predominantly formed under high hydrostatic pressure (>1 GPa).