Small polymer particles with a diameter of less than 5 mm called microplastics find their way into the environment from polymer debris and industrial production. Therefore a method is needed to ...identify and quantify microplastics in various environmental samples to generate reliable concentration values. Such concentration values, i.e. quantitative results, are necessary for an assessment of microplastic in environmental media. This was achieved by thermal extraction in thermogravimetric analysis (TGA), connected to a solid-phase adsorber. These adsorbers were subsequently analysed by thermal desorption gas chromatography mass spectrometry (TDS-GC-MS). In comparison to other chromatographic methods, like pyrolyse gas chromatography mass spectrometry (Py-GC-MS), the relatively high sample masses in TGA (about 200 times higher than used in Py-GC-MS) analysed here enable the measurement of complex matrices that are not homogenous on a small scale. Through the characteristic decomposition products known for every kind of polymer it is possible to identify and even to quantify polymer particles in various matrices. Polyethylene (PE), one of the most important representatives for microplastics, was chosen as an example for identification and quantification.
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•Using a thermal decomposition method for analysing PE microplastics in environmental matrices in one step.•Direct measuring without a pre selection.•Identification and quantification of polymers in environmental samples.
In order to determine the relevance of microplastic particles in various environmental media, comprehensive investigations are needed. However, no analytical method exists for fast identification and ...quantification. At present, optical spectroscopy methods like IR and RAMAN imaging are used. Due to their time consuming procedures and uncertain extrapolation, reliable monitoring is difficult. For analyzing polymers Py-GC-MS is a standard method. However, due to a limited sample amount of about 0.5 mg it is not suited for analysis of complex sample mixtures like environmental samples. Therefore, we developed a new thermoanalytical method as a first step for identifying microplastics in environmental samples. A sample amount of about 20 mg, which assures the homogeneity of the sample, is subjected to complete thermal decomposition. The specific degradation products of the respective polymer are adsorbed on a solid-phase adsorber and subsequently analyzed by thermal desorption gas chromatography mass spectrometry. For certain identification, the specific degradation products for the respective polymer were selected first. Afterwards real environmental samples from the aquatic (three different rivers) and the terrestrial (bio gas plant) systems were screened for microplastics. Mainly polypropylene (PP), polyethylene (PE) and polystyrene (PS) were identified for the samples from the bio gas plant and PE and PS from the rivers. However, this was only the first step and quantification measurements will follow.
•Determination of polymer specific degradation products.•Fast measurements without a time consuming sample preparation.•Identification of microplastic in real environmental samples.
Monitoring the ingestion of microplastics is challenging and suitable detection techniques are insufficiently used. Thus, misidentifying natural for synthetic microfibres cannot be avoided. As part ...of a framework to monitor the ingestion of microplastics in eelpout, this short report addresses the accurate identification of microfibres. We show that, following visual inspections, putatively synthetic microfibres are indeed of natural origin, as ascertained by spectrometric analyses. Consequently, we call for an inclusion of spectroscopic techniques in standardized microplastic monitoring schemes.
•Misidentifying natural microfibers for synthetic polymers.•Validating the origin of putatively synthetic microfibres by spectroscopic analyses.•Presuming, that the exposure of aquatic organisms to microplastics is frequently overestimated.•Calling for an adoption of spectroscopic techniques in standardized microplastic monitoring schemes.
In recent years, the development of smart drug delivery systems based on biodegradable polymeric nanoparticles has become of great interest. Drug-loaded nanoparticles can be introduced into the cell ...interior via endocytotic processes followed by the slow release of the drug due to degradation of the nanoparticle. In this work, poly(L-lactic acid) (PLLA) was chosen as the biodegradable polymer. Although common degradation of PLLA has been studied in various biological environments, intracellular degradation processes have been examined only to a very limited extent. PLLA nanoparticles with an average diameter of approximately 120 nm were decorated with magnetite nanocrystals and introduced into mesenchymal stem cells (MSCs). The release of the magnetite particles from the surface of the PLLA nanoparticles during the intracellular residence was monitored by transmission electron microscopy (TEM) over a period of 14 days. It was demonstrated by the release of the magnetite nanocrystals from the PLLA surface that the PLLA nanoparticles do in fact undergo degradation within the cell. Furthermore, even after 14 days of residence, the PLLA nanoparticles were found in the MSCs. Additionally, the ultrastructural TEM examinations yield insight into the long term intercellular fate of these nanoparticles. From the statistical analysis of ultrastructural details (e.g., number of detached magnetite crystals, and the number of nanoparticles in one endosome), we demonstrate the importance of TEM studies for such applications in addition to fluorescence studies (flow cytometry and confocal laser scanning microscopy).
Abstract Background Risk assessments of hemodynamically stable patients with pulmonary embolisms (PE) remain challenging. In this context hearttype fatty acid-binding protein (H-FABP), creatin kinase ...isoenzyme MB (CK-MB), and troponin I (TnI) may hold prognostic utility for patients with pulmonary embolism. Methods We included 161 consecutive normotensive (systolic blood pressure above 90 mm Hg) patients with confirmed PE to study the combined utility of echocardiographic signs of right ventricular dysfunction and several biomarkers (TnI, CK-MB, H-FABP). The primary endpoint was defined as death within 30 days after admission to the hospital. Results Elevated biomarkers were measured in 26 patients (16.1%) for HFABP, in 66 (41%) for TnI and in 41 (25.5%) for CK-MB. Echocardiography revealed right ventricular dysfunction (RVD) in 99 (61.5%) patients. Overall, 16 patients (9.9%) died within the study period. In the H-FABP positive group 15 (57.7%) patients died compared to 13 (19.7%) patients in the TnI positive group and 15 (37.5%) patients in the CK-MB positive group (H-FABP positive vs. TnI positive patients, p < 0.001; H-FABP positive vs. CK-MB positive patients p = 0.13; CK-MB positive vs. TnI positive patients p = 0.07). All elevated biomarkers correlated with the primary endpoint with H-FABP being strongly, CK-MB intermediately and TnI weakly associated with short term death (H-FABP r = 0.701, p < 0.001; CK-MB r = 0.486, p < 0.001; TnI r = 0.272, p = 0.001). In multivariate logistic regression analysis, a positive H-FABP test (OR 27.1, 95% CI 2.1 to 352.3, p = 0.001), elevated CK-MB levels (OR 5.3, 95% CI 1.3 to 23.3, p = 0.002) and a low systolic blood pressure on admission (OR 0.8, 95% CI 0.8 to 0.9, p < 0.001) emerged as independent predictors of 30-day mortality. Conclusions Both H-FABP and CK-MB are associated with short term mortality in normotensive PE patients and could be advantageous for risk stratification in this intermediate risk group.
A harmonization of sampling, sample preparation and detection is pivotal in order to obtain comparable data on microplastics (MP) in the environment. This paper develops and proposes a suitable ...sampling concept for waterbodies that considers different plastic specific properties and influencing factors in the environment.
Both artificial water including defined MP fractions and the discharge of a wastewater treatment plant were used to verify the derived sampling procedure, sample preparation and the subsequent analysis of MP using thermal extraction-desorption gas chromatography - mass spectrometry (TED-GC-MS).
A major finding of this paper is that an application of various particle size classes greatly improves the practical handling of the sampling equipment. Size classes also enable the TED-GC-MS to provide any data on the MP size distribution, a substantial sampling property affecting both the necessary sampling volume and the optimal sampling depth.
In the artificial water with defined MP fractions, the recovery rates ranged from 80 to 110%, depending on the different MP types and MP size classes. In the treated wastewater, we found both polyethylene and polystyrene in different size classes and quantities.
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•General physical and practical aspects for sampling water to detect microplastics.•Presentation of a filtration cascade procedure with defined size classes.•Validation experiments for the method's results in recovery rates of 80–110%.•Exemplary results of sampling from wastewater treatment plant.
Waste disposal of carbon nanotube (CNT) containing products is expected to be the most important pathway for release of CNTs into the environment. In the present work, the use of radiolabelled CNTs ...(14C-CNT) for polycarbonate polymer nanocomposites with 1 wt% 14C-CNT content allowed for the first time to quantify and differentiate the CNT release according to the type of impact along the materials' ageing history. After an initial exposure of the nanocomposite by solar-like irradiation, further environmental impacts were applied to composite material. They aimed at mimicking disposal site conditions that may induce further ageing effects and CNT release. This study included shaking in water, rapid temperature changes, soaking in humic acid solution as well as waste water effluent, and, finally, gentle mechanical abrasion. All ageing impacts were applied sequentially, both on pristine (control) and on solar-irradiated nanocomposites. All experiments were accompanied by absolute quantification of radioactive release as well as chemical and morphological analyses of the nanocomposite surfaces using infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The morphological analysis showed that spectral irradiation can uncover CNT networks on the outer nanocomposite surface layers by polymer degradation. After having subjected the solar-irradiated nanocomposite to all studied disposal site effect, the total radioactive release was quantified to amount to 64 mg CNT/m2, whereas only 0.8 mg CNT/m2 were found for the un-irradiated control sample. Solar degradation of polymers was thus found to significantly increase the propensity of the studied polymer nanocomposites to release CNTs during ageing effects at the product's end-of-life typical for disposal sites.
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•For the first time the release of 14C-labelled CNT from nanocomposites is quantified.•Artificial sunlight followed by degradation scenarios released CNT material.•The photodegradation uncovered and oxidized CNT material at the composites surface.
For the first time, the release of CNT material from CNT-containing composites was quantified after subjecting them to various degradation processes that may occur during the lifecycle of a nanocomposite.
Durch eine Additivierung von Kunststoffen mit Kohlenstoff-Nanoröhren (CNT) lassen sich ihre Eigenschaften gezielt optimieren. Die erzielten Leistungsverbesserungen können über steigende Nachfrage zu ...einem höheren Materialeinsatz der CNT-Polymerkomposite in den unterschiedlichsten technologischen Bereichen führen. CNT sind faserförmige Nanomaterialien und müssen nach WHO-Regularien (Weltgesundheitsorganisation) als potenziell krebserregende Risikomaterialien in Betracht gezogen wer-den. Der voraussichtlich steigende Marktanteil an CNT-haltigen Polymer-Verbundwerkstoffen und der damit zunehmende Kontakt mit Umwelt und Verbrauchern erfordern eine hinsichtlich CNT-Freisetzung und -Exposition fokussierte Forschung zur Risikoabschätzung für Mensch und Umwelt. Ziel dieser Arbeit ist die systematische Untersuchung des Kompositabbaus unter simulierten Umweltbedingungen. Dabei lag der Fokus auf der photo-induzierten Schädigung solcher CNT-Polymerkomposite, welche den Lebenszyklus dieser Materialien bei Langzeit-Außenanwendungen oder auf Deponien nachstellen soll. Dafür wurden drei verschiedene, handelsübliche Polymermatrizes – Polyamid 6, Polycarbonat und hochverdichtetes (HD-) Polyethylen – ausgewählt. Es wurden dabei die jeweiligen Abbauprozesse der Polymere unter verschiedenen Bestrahlungsbedingungen verfolgt. Die Einwirkungen auf den Degradationsverlauf wurden sowohl hinsichtlich unterschiedlicher CNT-Konzentrationen in den Materialen, als auch matrixabhängig untersucht, um die mögliche Freilegung von CNT aus dem Material abzuschätzen. Unter sonnenähnlicher, integraler Xe-Bestrahlung zeigten die PE-Komposite die größte Beständigkeit hinsichtlich des Polymerabbaus und daher nur eine geringfügige Freilegung von CNT an der Oberfläche. Ein vollständiger Matrixabbau unter Bildung eines CNT-Netzwerkes auf der Oberfläche wurde unter den gewählten Bedingungen bei den Polycarbonatkompositen erreicht. Im Allgemeinen verzögerte eine Additivierung mit CNT die Degradation der jeweiligen Matrizes, verglichen mit dem reinen Polymermaterial. Der Degradationsverlauf der Komposite konnte mit verschieden spektroskopischen Methoden reproduzierbar nachvollzogen werden. Der potenzielle Einfluss von CNT auf die Abbaumechanismen der Polymere wurde zusätzlich für den UV-Bereich wellenlängenspezifisch untersucht. Der Einfluss unterschiedlicher Oberflächentemperaturen, wie sie bei der sonnenähnlichen Bestrahlung durch die Materialfarbigkeit verursacht werden, auf die Degradation konnte relativiert werden. Untersuchungen zum Einfluss der CNT-Konzentration auf den CNT-Freilegungsgrad in Polycarbonat zeigten eine frühzeitige Degradation der Matrix und CNT-Freilegung mit steigendem CNT-Gehalt. Um Erkenntnisse über eine photo-induzierte Oxidation der an der Oberfläche freigelegten CNT zu gewinnen, konnte mittels verschiedener oberflächensensitiver Methoden eine geringe Oxidation der CNT analytisch nachgewiesen werden. Gelangen die oxidierten CNT in die Umwelt, könnte das durch eine höhere Hydrophilie auch eine erhöhte Bioverfügbarkeit bedingen. Über zusätzliche morphologische Beobachtungen des exponierten CNT-Netzwerks konnte eine Risikoabschätzung der potenziellen Emission von CNT und CNT-Fragmenten gemacht werden. Eine mögliche Quantifizierung der CNT-Freisetzung nach erfolgter photo-chemischer Degradation war in Zusammenarbeit mit Rhiem et al. mittels radioaktiv markierter inkorporierter CNT unter simulierten Umwelteinflüssen umsetzbar.
Waste disposal of carbon nanotube (CNT) containing products is expected to be the most important pathway for release of CNTs into the environment. In the present work, the use of radiolabelled CNTs ...((14)C-CNT) for polycarbonate polymer nanocomposites with 1 wt% (14)C-CNT content allowed for the first time to quantify and differentiate the CNT release according to the type of impact along the materials' ageing history. After an initial exposure of the nanocomposite by solar-like irradiation, further environmental impacts were applied to composite material. They aimed at mimicking disposal site conditions that may induce further ageing effects and CNT release. This study included shaking in water, rapid temperature changes, soaking in humic acid solution as well as waste water effluent, and, finally, gentle mechanical abrasion. All ageing impacts were applied sequentially, both on pristine (control) and on solar-irradiated nanocomposites. All experiments were accompanied by absolute quantification of radioactive release as well as chemical and morphological analyses of the nanocomposite surfaces using infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The morphological analysis showed that spectral irradiation can uncover CNT networks on the outer nanocomposite surface layers by polymer degradation. After having subjected the solar-irradiated nanocomposite to all studied disposal site effect, the total radioactive release was quantified to amount to 64 mg CNT/m(2), whereas only 0.8 mg CNT/m(2) were found for the un-irradiated control sample. Solar degradation of polymers was thus found to significantly increase the propensity of the studied polymer nanocomposites to release CNTs during ageing effects at the product's end-of-life typical for disposal sites.
As effective stroke treatment by thrombolysis is bound to a narrow time window excluding most patients, numerous experimental treatment strategies have been developed to gain new options for stroke ...treatment. However, all approaches using neuroprotective agents that have been successfully evaluated in rodents have subsequently failed in clinical trials. Existing large animal models are of significant scientific value, but sometimes limited by ethical drawbacks and mostly do not allow for long-term observation. In this study, we are introducing a simple, but reliable stroke model using permanent middle cerebral artery occlusion in sheep. This model allows for control of ischemic lesion size and subsequent neurofunctional impact, and it is monitored by behavioral phenotyping, magnetic resonance imaging, and positron emission tomography. Neuropathologic and (immuno)-histologic investigations showed typical ischemic lesion patterns whereas commercially available antibodies against vascular, neuronal, astroglial, and microglial antigens were feasible for ovine brain specimens. Based on absent mortality in this study and uncomplicated species-appropriate housing, long-term studies can be realized with comparatively low expenditures. This model could be used as an alternative to existing large animal models, especially for longitudinal analyses of the safety and therapeutic impact of novel therapies in the field of translational stroke research.
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