Enzyme self-assembly on naked iron oxide nanoparticles for aminoaldehyde biosensing.

The preservation of enzymatic activity is a fundamental requirement for exploiting hybrid nano-bio-conjugates, and the control over protein-nanoparticle interactions, leading to stable and catalytically active hybrids, represents the key for designing new biosensing platforms. In this scenario, surface active maghemite nanoparticles (SAMNs) represent a new class of naked magnetic nanoparticles, displaying peculiar electrocatalytic features and the ability to selectively bind proteins. Recombinant aminoaldehyde dehydrogenase from tomato (SlAMADH1) was used as a model protein, and successfully immobilized by self-assembly on the surface of naked SAMNs, where its enzymatic activity resulted preserved for more than 6 months. The hybrid nanomaterial (SAMN@SlAMADH1) was characterized by UV-Vis spectroscopy, mass spectrometry, and TEM microscopy, and applied for the development of a biosensor for the determination of aminoaldehydes in alcoholic beverages. Measurements were carried out in a low volume electrochemical flow cell comprising a SAMN modified carbon paste electrode for the coulometric determination of the NADH produced during the enzymatic catalysis. The present findings, besides representing the first example of an electrochemical biosensor for aminoaldehydes in an alcoholic matrix, open the door to the use of immobilized enzymes on naked metal oxides nanomaterials for biosensing.

Mass poisoning with NPS: 2C-E and Bromo-DragonFly.

BACKGROUND: Reports of intoxications with new psychoactive substances (NPS) mostly involve young people, as they are the main consumers of these types of drugs. This report centers on a case that was unusual due to it being a mass-poisoning event involving middle-aged individuals who had consumed a combination of the two different new psychoactive drugs 2,5-dimethoxy-4-ethylphenethylamine (2C-E) and 1-(8-bromofuro[2,3-f][1]benzofuran-4-yl)-2-propanamine (Bromo-DragonFly, BDF). CASE HISTORY: The mass poisoning of 29 individuals (24-56 years old) resulted in their admission to six different hospitals with severe symptoms of intoxication. All symptoms manifested after consumption of an unknown drug formulation around lunchtime during an esoteric weekend seminar. INVESTIGATION: Urine (n = 11) and blood samples (n = 29), collected from the 29 individuals for police investigation, were analyzed with immunochemical techniques, GC/MS and LC-MS/MS. 2C-E was confirmed in seven urine samples, but not in blood. BDF was confirmed in all urine samples, and in 17 blood samples. The blood samples exhibited BDF concentrations between ca. 0.6 and ca. 2.0 µg/L, while urine concentrations of BDF ranged from ca. 1.6 to 35 µg/L. The concentration of 2C-E in urine was found to be between ca. 1.5 and 183 µg/L. All patients made a complete recovery, although some had required mechanical ventilation. CONCLUSION: The investigation and the presentation of this case illustrates not only mass intoxication with 2C-E and BDF, with corresponding blood and urine concentrations, but also the necessity of collecting urine samples in cases where NPS-consumption is suspected, in order to improve the chances of analytical detection.

Quantification and Stability Determination of Surface Amine Groups on Silica Nanoparticles Using Solution NMR.

Surface chemistry is a critical factor for determining the behavior of a nanomaterial after incorporation in composites, devices, and biomedical products, and is also important for nanotoxicology studies. We have developed an optimized protocol for dissolution of aminated silicas and determination of functional-group contents by quantitative 1H NMR (qNMR) analysis of the released amines. A number of variables were optimized for the dissolution protocol, including the base concentration, mass of silica, time, temperature, and method of sample agitation, in order to achieve adequate NMR signals for quantification. The protocol was tested using nanoparticles from a single commercial supplier with sizes ranging from 20 to 120 nm that were functionalized with 3-aminopropyl groups. Interestingly the batch-to-batch variability for some sizes of these aminated silicas was as high as 50%. Amine contents measured by a ninhydrin colorimetric assay were typically ∼20% lower than those measured by qNMR, consistent with measurement of only ninhydrin-reagent accessible amines. The dissolution-qNMR protocol was compatible with aminated silicas from other commercial suppliers, and in these cases, an even larger variability in surface coverage was observed. Silica nanoparticles with longer-chain amines and variable amine loadings were synthesized to demonstrate the ability to quantify amines with more complex structures and to assess the limit of quantification for the dissolution-qNMR method. Finally, the stability of the aminated nanoparticles was examined. Loss of 3-aminopropyl groups occurred in water at room temperature and was significantly more rapid at higher temperatures. Amine loss increased with increasing surface coverage and was slower for long-chain amines, consistent with studies of amine stability on planar silica. Overall, this work highlights the importance of developing methods for quantifying surface functionalization, particularly given the variability in surface coverage for commercial samples, and for ensuring that the amine group is stable under its usage conditions.

Development of in situ product removal strategies in biocatalysis applying scaled-down unit operations.

An experimental platform based on scaled-down unit operations combined in a plug-and-play manner enables easy and highly flexible testing of advanced biocatalytic process options such as in situ product removal (ISPR) process strategies. In such a platform, it is possible to compartmentalize different process steps while operating it as a combined system, giving the possibility to test and characterize the performance of novel process concepts and biocatalysts with minimal influence of inhibitory products. Here the capabilities of performing process development by applying scaled-down unit operations are highlighted through a case study investigating the asymmetric synthesis of 1-methyl-3-phenylpropylamine (MPPA) using ω-transaminase, an enzyme in the sub-family of amino transferases (ATAs). An on-line HPLC system was applied to avoid manual sample handling and to semi-automatically characterize ω-transaminases in a scaled-down packed-bed reactor (PBR) module, showing MPPA as a strong inhibitor. To overcome the inhibition, a two-step liquid-liquid extraction (LLE) ISPR concept was tested using scaled-down unit operations combined in a plug-and-play manner. Through the tested ISPR concept, it was possible to continuously feed the main substrate benzylacetone (BA) and extract the main product MPPA throughout the reaction, thereby overcoming the challenges of low substrate solubility and product inhibition. The tested ISPR concept achieved a product concentration of 26.5 gMPPA · L-1 , a purity up to 70% gMPPA · gtot-1 and a recovery in the range of 80% mol · mol-1 of MPPA in 20 h, with the possibility to increase the concentration, purity, and recovery further. Biotechnol. Bioeng. 2017;114: 600-609. © 2016 Wiley Periodicals, Inc.

Enhanced sensitivity of double gate junctionless transistor architecture for biosensing applications.

In the present work, we demonstrate the potential of double gate junctionless (JL) architecture for enhanced sensitivity for detecting biomolecules in cavity modulated field effect transistors (FETs). The higher values of body factor, achieved in asymmetric gate operation under impact ionization is utilized for enhanced sensing margin which is nearly five times higher than compared to symmetrical mode operation. The intrinsic detection sensitivity is evaluated in terms of threshold voltage change, and the ratio of drain current in the presence and absence of biomolecules in JL nanotransistors. It is shown that asymmetric mode JL transistor achieves a higher degree of detection sensitivity even for a partially filled cavity. The work demonstrates the potential of JL channel architecture for cavity based dielectric modulated FET biosensors.

Single-particle speciation of alkylamines in ambient aerosol at five European sites.

Alkylamines are associated with both natural and anthropogenic sources and have been detected in ambient aerosol in a variety of environments. However, little is known about the ubiquity or relative abundance of these species in Europe. In this work, ambient single-particle mass spectra collected at five sampling sites across Europe have been analysed for their alkylamine content. The aerosol time-of-flight mass spectrometer (ATOFMS) data used were collected in Ireland (Cork), France (Paris, Dunkirk and Corsica) and Switzerland (Zurich) between 2008 and 2013. Each dataset was queried for mass spectral marker ions associated with the following ambient alkylamines: dimethylamine (DMA), trimethylamine (TMA), diethylamine (DEA), triethylamine (TEA), dipropylamine (DPA) and tripropylamine (TPA). The fraction of ambient particles that contained detectable alkylamines ranged from 1 to 17 % depending on location, with the highest fractions observed in Paris and Zurich in the winter months. The lowest fractions were observed at coastal sites, where the influence of animal husbandry-related alkylamine emissions is also expected to be lowest. TMA was the most ubiquitous particle phase alkylamine detected and was observed at all locations. Alkylamines were found to be internally mixed with both sulphate and nitrate for each dataset, suggesting that aminium salt formation may be important at all sites investigated. Interestingly, in Corsica, all alkylamine particles detected were also found to be internally mixed with methanesulphonic acid (MSA), indicating that aminium methanesulphonate salts may represent a component of marine ambient aerosol in the summer months. Internal mixing of alkylamines with sea salt was not observed, however. Alkylamine-containing particle composition was found to be reasonably homogeneous at each location, with the exception of the Corsica and Dunkirk sites, where two and four distinct mixing states were observed, respectively.

Enantioseparation of benzofurys and other novel psychoactive compounds by CE and sulfobutylether ß-cyclodextrin as chiral selector added to the BGE.

The illicit drug market of psychoactive substances for human abuse is continuously expanding and developing. Besides already known substance classes like cathinones, amphetamines or synthetic cannabinoids, further derivatives such as benzofurys, thiophenes, and structural analogues of methylphenidate entered the global market recently. As many of these new compounds contain a stereogenic centre it is supposed that their isomers may differ in their pharmacological effects as it is the case with amphetamines or several chiral active pharmaceutical ingredients, for instance. In the course of this study, a method for the chiral separation of a set of 16 recreational drugs by CE was developed. The aim was to separate the analytes into their enantiomers at equal conditions within short time. Sulfobutylether ß-cyclodextrin served as chiral selector in an aqueous ammonium acetate solution containing ACN. For method optimization, methedrone and ethylphenidate were used as model compounds to find the appropriate concentration of chiral selector. Moreover, the influence of the pH value on enantioseparation was tested. Fourteen or 16 mM sulfobutylether ß-cyclodextrin, 50 mM ammonium acetate solution (pH 4.5) with 10% ACN were found to be optimal for enantioseparation of seven benzofurys, four cathinones, two diphenidines, ethylphenidate, methiopropamine, and thiothinone. Most of them were baseline resolved at migration times below 25 min.

Development of analytical methods for the quantification of metabolites of lesogaberan in a MIST investigation.

Analytical methods were developed for the determination of six metabolites of lesogaberan to be used in quantitative determinations of metabolites according to the guidelines of Metabolites in Safety Testing. The γ-amino butyric acid type B receptor agonist lesogaberan and its metabolites are small polar molecules and hydrophilic interaction liquid chromatography was found to be a suitable separation mode. The samples were prepared using protein precipitation and negative electrospray ionization tandem mass spectrometry was used for detection. Initially, exploratory methods for six metabolites were set up for analysis of human plasma samples taken after repeated administration of a high oral dose of lesogaberan. The purpose was to establish which metabolites were present at concentrations significant for further investigation. Four of the six metabolites were then found at clearly detectable concentrations. The analytical methods for these four metabolites were further elaborated and then taken through a qualification procedure, which showed acceptable accuracy (86-114%), precision (<9%) and good linearity in the range 0.03-5 µmol/L. No interferences were seen from endogenous plasma components.

Synthesis and biological evaluation of novel propargyl amines as potential fluorine-18 labeled radioligands for detection of MAO-B activity.

The aim of this project was to synthesize and evaluate three novel fluorine-18 labeled derivatives of propargyl amine as potential PET radioligands to visualize monoamine oxidase B (MAO-B) activity. The three fluorinated derivatives of propargyl amine ((S)-1-fluoro-N,4-dimethyl-N-(prop-2-ynyl)-pent-4-en-2-amine (5), (S)-N-(1-fluoro-3-(furan-2-yl)propan-2-yl)-N-methylprop-2-yn-1-amine (10) and (S)-1-fluoro-N,4-dimethyl-N-(prop-2-ynyl)pentan-2-amine (15)) were synthesized in multi-step organic syntheses. IC(50) values for inhibition were determined for compounds 5, 10 and 15 in order to determine their specificity for binding to MAO-B. Compound 5 inhibited MAO-B with an IC(50) of 664 ± 48.08 nM. No further investigation was carried out with this compound. Compound 10 inhibited MAO-B with an IC(50) of 208.5 ± 13.44 nM and compound 15 featured an IC(50) of 131.5 ± 0.71 nM for its MAO-B inhibitory activity. None of the compounds inhibited MAO-A activity (IC(50) > 2 µM). The fluorine-18 labeled analogues of the two higher binding affinity compounds (10 and 15) (S)-N-(1-[(18)F]fluoro-3-(furan-2-yl)propan-2-yl)-N-methylprop-2-yn-1-amine (16) and (S)-1-[(18)F]fluoro-N,4-dimethyl-N-(prop-2-ynyl)pentan-2-amine (18) were both prepared from the corresponding precursors 9A, 9B and 14A, 14B by a one-step fluorine-18 nucleophilic substitution reaction. Autoradiography experiments on human postmortem brain tissue sections were performed with 16 and 18. Only compound 18 demonstrated a high selectivity for MAO-B over MAO-A and was, therefore, chosen for further examination by PET in a cynomolgus monkey. The initial uptake of 18 in the monkey brain was 250% SUV at 4 min post injection. The highest uptake of radioactivity was observed in the striatum and thalamus, regions with high MAO-B activity, whereas lower levels of radioactivity were detected in the cortex and cerebellum. The percentage of unchanged radioligand 18 was 30% in plasma at 90min post injection. In conclusion, compound 18 is a selective inhibitor of MAO-B in vitro and demonstrated a MAO-B specific binding pattern in vivo by PET in monkey. It can, therefore, be considered as a candidate for further investigation in human by PET.

Early pharmaceutical evaluation of a crystalline and hygroscopic GABAB receptor agonist.

Lesogaberan is a potent gamma amino butyric acid agonist and has been evaluated for its utility in treatment of gastroesophageal reflux disease. Lesogaberan is a crystalline substance that absorbs considerable amounts of water above 65% relative humidity (RH) where it also liquifies. As a result of the hygroscopicity of the zwitterionic form an investigation of different salt forms was performed. Since the test compound is polar and lacks ultraviolet (UV) chromophore, conventional separation and detection techniques could not be used to characterise the test compound and the impurities. The analytical techniques are described, focusing on the capillary electrophoresis method with indirect UV detection for purity, the liquid chromatographic method for enantiomeric separation with derivatisation with UV chromophore and two complementary nuclear magnetic resonance (NMR) approaches (¹9F-NMR and ¹H-NMR) for impurities. The stability study in solution showed that solutions between pH 5 and 7 were the most stable ones, but after some time degradation occurred at room temperature. When bulk lesogaberan was stored at 25°C/60% RH no chemical degradation was observed after 1 year. At 40°C/75% RH, where the compound liquefies, a significant degradation was observed after 1 month. However, in a closed container (= 40°C) or as a napsylate salt, no degradation of lesogaberan was observed at 40°C/75% RH.

Medical management of a potentially toxic accidental trialkylamine ingestion during spaceflight.

INTRODUCTION: To reduce excessive iodine consumption by astronauts, the National Aeronautics and Space Administration (NASA) has developed various methods of removing residual iodine after iodine-based water purification aboard spacecraft. The Low Iodine Residual System (LIRS) was developed as an iodine removal system for use aboard the space shuttle. This is a case report of an accidental, potentially toxic ingestion by astronauts aboard a space shuttle mission following exposure to contaminated water from LIRS filtration and the medical response operations that followed. CASE REPORT: Astronauts ingested significant levels of trialkylamines from water that had passed through gamma-irradiated, de-iodination resin in the LIRS hardware. Medical response operations included crew evaluations, consultations with toxicologists and systems experts, hardware testing, contaminant evaluation, and close crewmember follow-up. DISCUSSION: Despite the significant ingestion there were no adverse clinical symptoms in any of the exposed astronauts; however, the case highlights a simple pitfall in the classification of hardware that ultimately lead to a potentially harmful toxic ingestion among the crewmembers, and the real-time response of medical personnel to ensure crew safety.

Electrochemical sensing based on gold nanoparticle-decorated halloysite nanotube composites.

Novel gold nanoparticle-decorated halloysite nanotube (AuNP-HNT) composites were effectively synthesized and then used for electrochemical sensing applications. The AuNP-HNT nanocomposites were characterized by transmission electron microscopy, field emission scanning electron microscopy, zeta potential, and UV-Vis spectroscopy. The AuNP-HNT composite-based modified electrode exhibited high eletrocatalytic activity to the reduction of hydrogen peroxide (H(2)O(2)) with a linear range of 5.0×10(-6) to 2.55×10(-4)M and a detection limit of 1×10(-6)M (signal/noise=3), indicating that it could be used as a novel nonenzymatic electrochemical H(2)O(2) sensor. Furthermore, the Ru(bpy)(3)(2+)/AuNP-HNT/Nafion composite film modified electrode exhibited good electrochemiluminescence activity for determining tripropylamine.

A liquid chromatography/tandem mass spectrometry assay for the analysis of atomoxetine in human plasma and in vitro cellular samples.

A simple, rapid and sensitive method for quantification of atomoxetine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. This assay represents the first LC-MS/MS quantification method for atomoxetine utilizing electrospray ionization. Deuterated atomoxetine (d3-atomoxetine) was adopted as the internal standard. Direct protein precipitation was utilized for sample preparation. This method was validated for both human plasma and in vitro cellular samples. The lower limit of quantification was 3 ng/mL and 10 nm for human plasma and cellular samples, respectively. The calibration curves were linear within the ranges of 3-900 ng/mL and 10 nm to 10 µm for human plasma and cellular samples, respectively (r(2) >0.999). The intra- and inter-day assay accuracy and precision were evaluated using quality control samples at three different concentrations in both human plasma and cellular lysate. Sample run stability, assay selectivity, matrix effect and recovery were also successfully demonstrated. The present assay is superior to previously published LC-MS and LC-MS/MS methods in terms of sensitivity or the simplicity of sample preparation. This assay is applicable to the analysis of atomoxetine in both human plasma and in vitro cellular samples.

The effect of contact lens materials on disinfection activity of polyquaternium-1 and myristamidopropyl dimethylamine multipurpose solution against Staphylococcus aureus.

OBJECTIVES: This study examined the interaction of seven different lens materials with a multipurpose solution (MPS) containing the disinfectants polyquaternium-1 (0.001%) and myristamidopropyl dimethylamine (0.0005%). The objective of this study was to determine whether the different lens materials affect the concentration of a disinfectant in this commercially available MPS and the efficacy of the disinfectant against Staphylococcus aureus. METHODS: Silicone hydrogel lenses (galyfilcon A, senofilcon A, comfilcon A, enfilcon A, balafilcon A, and lotrafilcon B) and a conventional hydrogel lens (etafilcon A) were soaked in polypropylene lens cases filled with commercially available MPS containing 0.001% polyquaternium-1 and 0.0005% myristamidopropyl dimethylamine for 6, 12, 24, 72, and 168 hours. Empty lens cases were also filled with MPS. After each time point, solutions from cases containing the seven types of lenses and controls were assayed for activity against S. aureus according to International Standards Organization 14729 standard with modifications. Test solutions were analyzed for polyquaternium-1 and myristamidopropyl dimethylamine concentration at each time point. RESULTS: The concentration of polyquaternium-1 and myristamidopropyl dimethylamine remaining in the lens cases was reduced only slightly over time. Storage with the lenses did not adversely affect biocidal efficacy of the solution, and in some cases, it was significantly better (P=0.0029). CONCLUSION: The efficacy of this polyquaternium-1 and myristamidopropyl dimethylamine MPS to kill S. aureus was not adversely affected by the presence of lens materials soaking in the cases. Thus, current methods for performing solution antimicrobial testing should be reevaluated.

Evaluation of electrogenerated chemiluminescence from a neutral Ir(III) complex for quantitative analysis in flowing streams.

Though recently Ir(III) complexes have attracted much interest in electrochemiluminescent (ECL) analysis due to their high emission in various wavelengths, there were a few studies reported on its analytical applications. In this study, we evaluate the ECL from (pq)(2)Ir(acac) (pq = 2-phenylquinolate, acac = acetylacetonate) for the use in flow injection analysis. An aqueous solution of the analyte and (pq)(2)Ir(acac) passes through the reaction/observation cell, and then ECL reaction is generated by electrochemical initiation on the analyte and (pq)(2)Ir(acac). Tri-n-propylamine (TPrA) is used as a representative analyte for evaluation. Additionally, a comparison is made of the relative ECL intensities obtained for a variety of analytes including oxalate, amino acids, aliphatic amines, and NADH. The (pq)(2)Ir(acac) produces efficient ECL upon TPrA exhibiting the limit of detection of 5 nM with a linear range of 3 orders of magnitude in concentration whereas 20 nM is observed in the conventional Ru(bpy)(3)(2+) system. It shows particular sensitivity advantages for oxalate, proline, and tartaric acid. The ECL generation upon various analytes proposes direct applicability of (pq)(2)Ir(acac) as a post-column detection tool.

High electrochemiluminescence of a new water-soluble iridium(III) complex for determination of antibiotics.

A new water-soluble iridium(III) diimine complex with appended sugar was synthesized and characterized. The electrochemiluminescent behavior of the new complex in aqueous buffer was first studied and the ECL signal was found to be much higher than that of [Ru(bpy)(3)](2+) at a Pt working electrode. Tri-n-propylamine (TPA) and antibiotics were determined by the ECL of the iridium(III) complex in aqueous buffer at the Pt electrode and the method was found to show good sensitivity and reproducibility. The new iridium(III) complex was found to display good solubility in aqueous solution and a strong ECL signal at the Pt electrode, which might open up the possibility of its application in analysis.

Spectrophotometric and spectrofluorimetric determination of atomoxetine in pharmaceutical preparations.

Visible spectrophotometric and spectrofluorimetric methods were developed for the determination of atomoxetine in pharmaceutical preparations. The spectrophotometric method was based on a nucleophilic substitution reaction of atomoxetine with 1,2-naphthoquinone-4-sulphonate (NQS) in an alkaline medium to form an orange-colored product. The absorbance-concentration plot is rectilinear over the range 5-40 microg mL(-1). The limits of detection and quantification were calculated to be 0.02 microg mL(-1) and 0.06 microg mL(-1), respectively. The spectrofluorimetric method was based on the derivatization reaction of 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) with atomoxetine to produce a fluorescent derivative. The formed highly fluorescent derivative that was measured at 462 nm after excitation at 533 nm. The fluorescence-concentration plot is rectilinear over the range 10-500 ng mL(-1). The limits of detection and quantification were calculated to be 0.19 ng mL(-1) and 0.57 ng mL(-1). The analytical performance of both methods was fully validated, and the results were satisfactory. The methods have been successfully applied for the determination of the studied drug in capsules and the results obtained ware in good agreement with those obtained by the reference method.

A novel solid-state electrochemiluminescence sensor based on Ru(bpy)(3)(2+) immobilization on TiO(2) nanotube arrays and its application for detection of amines in water.

Many amines are proven or suspected to be carcinogenic and have been implicated in inducing cancer of the bladder. Therefore, the monitoring of their levels in environmental samples is important for the protection of health and the environment. Herein, a novel method for effective immobilization of Ru(bpy)(3)(2+) on the electrode surface of TiO(2) nanotube arrays (TNs) is developed for the first time. The method involves Ru(bpy)(3)(2+) spontaneously adsorbed on the surface of negatively charged TiO(2) nanotubes due to electrostatic interaction to produce a Ru(bpy)(3)(2+) /TNs/Ti (Ru-TNs-Ti) solid-state electrochemiluminescence (ECL) sensor. The prepared solid-state sensor was used to detect the changes of concentrations of pollutant tripropylamine (TPA) in water. The sensor exhibits excellent ECL behavior, very good stability and high sensitivity. This study may provide new insight into the design and preparation of an advanced solid-state ECL sensor for monitoring of amines in water.

Fabrication of chemiluminescence sensor based on conducting polymer@SiO2/Nafion composite film.

Tris(2,2'-bipyridyl)ruthenium (II) (Ru(bpy)2+) electrogerated chemiluminescence (ECL) sensor was fabricated by immobilization of Ru(bpy)2+ complex on conducting polymer@SiO2/Nafion composite film on surface of glassy carbon electrode. The conducting polymer@SiO2 nanocomposites were prepared by coating polyaniline (PANI), polypyrrole (PPy), and polythiophene (PTh) on the surface of the SiO2 sphere. The conducting polymer@SiO2 nanocomposite was characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and atomic force microscopy (AFM). The sensitivity and reproducibility of the prepared ECL sensor to tripropylamine (TPA) was evaluated. As a result, the PPy@SiO2 composite electrode exhibited high sensitivity and good reproducibility compared to that obtained with PANI@SiO2 and PTh@SiO2 composite electrodes because of the strong interaction between PPy@SiO2 and Ru(bpy)2+ complex.

The toxicity of Roundup® 360 SL formulation and its main constituents: glyphosate and isopropylamine towards non-target water photoautotrophs.

The toxicity of commercial formulation of Roundup® 360 SL, widely used, nonselective herbicide and its main constituents, glyphosate (PMG), equimolar (1:1) isopropylamine salt of glyphosate (GIPA) and isopropylamine (IPA) was examined towards eight aquatic microphotoautotrophs; seven cyanobacterial strains representing either saline or freshwater communities, and common eukaryotic algae Chlorella vulgaris Beijerinck. Autotrophs were cultured 21 days in their appropriate standard media supplemented with various amounts of Roundup®, glyphosate, GIPA and IPA. The determination of the growth of examined photoautotrophs was performed by time-course measurements of total chlorophyll content in experimental cultures. The growth rates related to corresponding concentrations of chemicals, the EC(50) values and generation doubling time were determined in order to present the toxicity Roundup® 360 SL formulation and its main constituents. Market available formulation of Roundup® was found to possess toxicity significantly higher than this, attributed to its main constituents; however both these compounds, isopropylamine and glyphosate, also inhibited the growth of examined strains in a dose-dependent manner. Notably, the interpretation of toxicity of the examined substances was found to be significantly dependent on the method of EC(50) calculation. The choice of molar or weight concentration of substances tested separately and in specific formulation was found to be essential in this matter. Due to these findings the EC(50) values were calculated based either on molar or on weight concentrations. Considering Roundup® 360 SL formulation, these values ranged from 10(-3) up to 10(-1) mM and they were one order of magnitude lower than those found for isopropylamine. Quite surprisingly the minimum EC(50) values found for glyphosate did not reach micromolar concentrations, whereas most of the EC(50) values revealed to IPA did not exceed this range. Notably, in all the cases except for Synechocystis aquatilis Sauvageau, isopropylamine alone was indicated as more toxic than glyphosate.