Chemische Charakterisierung und Spurenanalytik
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Eingeladener Vortrag
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Molecularly Imprinted Polymers with Integrated Fluorescence as Versatile Biomimetic Sensing Matrices
(2018)
Molecularly imprinted polymers (MIPs) are an established, versatile and high-performance matrix for the selective separation or enrichment of (bio)chemical species, especially small molecules of biochemical or environmental relevance. MIPs are prepared through the polymerization of a mixture of functional monomers and cross-linkers in the presence of the template with subsequent extraction of the latter. Conceptionally, this process can be seen as mimicking in a strongly accelerated, though single-step manner a biological process such as antibody formation. Because the resulting MIPs contain cavities in their matrix that are complementary in size, shape and electronic/ electrostatic or hydrogen bonding demand to the imprinted target molecule or template, these polymers are frequently termed “artificial antibodies”. Compared to natural antibodies, they are chemically and physically much more robust. Regarding sensitivity and selectivity, however, there is still a gap to bridge before MIPs can fully compete with antibodies.
Another favorable aspect that distinguishes MIPs from antibodies is that they can be endowed with an explicit function, allowing the use of MIPs in applications that require more than only an efficient binder. For instance, if specifically designed and polymerizable fluorescent indicators are integrated as functional monomers into a MIP, direct fluorescence sensing can be accomplished. Because MIPs can be prepared in a variety of different formats, their combination with miniaturized or other specific analytical techniques or sensory devices is possible, especially when the transduction mode is light. This presentation will introduce basic design considerations, challenges, limitations and the potential that lies with such sensor materials with some recent examples of our group, targeting various organic oxoanions as analytes.
Contamination of natural bodies of water with oil and lubricants (or generally, hydrocarbon derivatives such as petrol, fuel and others) is a commonly found phenomenon around the world due to the extensive production, transfer and use of fossil fuels. The timely identification of these contaminants is of utmost importance, since they directly affect water quality and represent a risk for wildlife and human health even in trace amounts.
In this work, we develop a simple system for the on-field detection of total petroleum hydrocarbons (TPH) in water and soil, the "Spectrocube". The test is based on the measurement of the fluorescence signal emitted by the molecular rotor 4-DNS-OH dye. This dye is embedded in a hydrophobic polymeric matrix (PVDF), avoiding interactions of water with the dye and providing a robust support for use in test-strip fashion. The test-strip’s fluorescence intensity increases linearly at low concentrations of TPH, reaching a saturation value at higher concentrations.
For excitation and evaluation of the test-strip fluorescence, a simple miniature optical system was designed. The system works semi-quantitatively as solvent-free TPH detection kit, as well as quantitatively when using a simple cyclopentane extraction step. To simplify the fluorescence read-out, the device is coupled to a tablet computer via Bluetooth, running a self-programmed software ("app").
Nanoparticles (NPs) have found a wide range of applications in research and industry. Thereby the interaction of NPs with biological systems like cells has become a major field of interest, ranging from medical applications to nanotoxicology. Size, shape and surface modification of the nanomaterials determine the uptake rate and pathway into the cells, and therefore impact specific cell components and processes.
In recent years, elemental imaging of biological samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is gaining more and more importance. Improvements concerning both spatial resolution (down to 1 µm) and signal-to-background ratio due to low-dispersion LA chambers make LA-ICP-MS particularly interesting for single cell analysis.
Here LA-ICP-MS was applied for the imaging of individual cells to study the uptake and intracellular processing of metal-containing nanostructures. The cells were incubated with different NPs under varying experimental conditions and afterwards fixed with para-formaldehyde and dried for LA analysis. High-spatial resolution LA-ICP-MS was achieved by careful optimisation of the laser ablation parameters.
Our findings show, that LA-ICP-MS is applicable to localize NP aggregates within cellular compartments. The uptake efficiency depends strongly on the physicochemical properties of the nanostructures as well as on the incubation conditions like concentration and incubation time.
The results demonstrate the potential of LA-ICP-MS providing insight into nanoparticle-cell interaction dependent on experimental parameters.
Statistic process control as well as process capability demand for calibrated determination of layer thicknesses in various industries, e.g. automotive, aerospace, microelectronics manufacturing. Calibration requires well know and well characterized samples. A calibration laboratory accredited according to DIN EN ISO 17025 has the objective to distribute standards traceable to SI units to industrial laboratories for quality control of manufacturing of various products. Especially, the thickness determination of thin metallic coatings e.g. from galvanic processes or layer deposition using X-Ray Fluorescence can be significantly improved by customized calibration samples. This is essential as the measurement uncertainty directly correlates to the capability performing reliable control of processes with high yield. For calibration laboratories, the validation of results using round robins and the direct comparison to national metrology institutes is a prerequisite to demonstrate the competence to perform calibration services.
In this paper a strategy to obtain traceability and validation for thin alloy layers as well as first results are presented. The combined use of the accredited method for determination of mass per area from measurement of mass and area combined with standard free X-Ray Fluorescence as well as chemical analysis of dissolved samples with thin layers is deployed for material systems as NixZn1-x as well as NixP1-x. The obtained results are compared to reference free X-Ray Fluorescence at the BESSY II laboratories of Physikalisch-Technische Bundesanstalt. An excellent agreement of the obtained measured values as mass per unit area and alloy concentrations from the different applied methods within the measurement uncertainty was observed for NixP1-x showing the successful performed traceability of the calibration samples to SI units in combination with a validation of results by national metrology institutes and the round robin approach.
Die ehemals wegen komplexer Technik und vergleichsweise hohen Wartungskosten beim Anwender ungeliebte Prozessanalysentechnik (PAT) erfährt sich mittlerweile immer mehr als etablierender Bereich mit einem großen Zuwachs und Dynamik. Die Prozesskontrolle und -steuerung über physikalische Kenngrößen wie Druck und Temperatur lässt eine weitere Optimierung der Anlagen kaum mehr zu. Nur mittels stoffspezifischer Analysen lassen sich Rohstoffschwankungen, Ausbeuten und Energieeinsatz konsequent optimieren.
Der systematische Einsatz der Prozessanalysentechnik verändert Prozesse und Produktionsumgebungen und hat damit die Chance, Kernstück dezentral automatisierter Produktionseinheiten zu werden. Ein neuer Arbeitskreis der NAMUR AK 3.7 „Smarte Sensorik, Aktorik und Kommunikation“ wird diesem verstärkt Rechnung tragen. Es werden reale Anwendungsbeispiele aufgezeigt, die eine schnelle Amortisation von PAT im Prozess untermauern.
To keep up with emerging mycotoxins and their transformation products fast and reliable toxicity tests are needed. Toxicity testing of mycotoxins is carried out usually by performing in vitro assays or is evaluated by using laboratory animals like mice, rats or chicken in in vivo studies.
Settled between classical in vitro approaches and in vivo studies with higher animals are tests with the nematode Caenorhabditis elegans. Since Sydney Brenner described 1974 the cultivation and handling of C. elegans, this worm is widely used as model organism in developmental biology and neurology. Due to many benefits like easy and cheap cultivation, a completely sequenced genome and short generation time, it also plays an important role in toxicological research. Finally, the high number of conserved genes between human and C. elegans make the worm an ideal candidate for toxicological investigations.
In this study we used C. elegans to assess the toxic effects of the relevant food mycotoxin citrinin (CIT), the mycoestrogen zearalenone (ZEN) and the modified mycotoxin ZEN-14-sulfate (ZEN-14-S) on different lifetable parameters including reproduction, thermal and oxidative stress tolerance and lifespan. All tested mycotoxins significantly decreased the amount of offspring. In case of ZEN and CIT also significant negative effects on stress tolerance and lifespan were observed compared to the control group.
Moreover, metabolization of mycotoxins in the worms was investigated by using LC MS/MS. Extraction of the worms treated 5 days with mycotoxin-containing and UVC-killed bacteria showed metabolization of ZEN to α-ZEL and β-ZEL (ZEL = zearalenol, ratio about 3:2). ZEN 14-S was reduced to ZEL 14-S and CIT was metabolized to mono hydroxylated CIT.
An overview about different analytical approaches will be presented of how to detect metals in individual biological cells by use of ICP-MS. For this purpose, we are using different sample introduction systems for ICP-MS for detection, imaging and quantification of metals at cellular levels.
By use of laser ablation, we have studied the up-take by and distribution of nanoparticles in single cells. Recently we have developed staining techniques to measure protein and DNA content of cells and identifying the cell status by immunoassays using metal-tagging of antibodies. New research based on cell arrays will be shortly discussed.
Using pneumatic nebulization and microdroplet generation, we have also studied the up-take of nanoparticles and toxic metals as well as essential elements in single cells using different ICP-MS mass spectrometric concepts (sector field instrument, triple-quad instrument, time of flight (CyTOF) instrument).
The different ICP-MS based methods will be compared concerning their analytical figures of merit and their strengths and weaknesses will be evaluated.
We are using LA-ICP-MS to quantify metals in biological cells and thin cuts of tissues from varies organs. Different applications will be presented to demonstrate the state of the art of bioimaging to visualize the elemental distribution pattern in soft bio-materials (tissue, single cells) of metals, metal containing stains and metal-tagged antibodies. For this purpose, different strategies for metal tagging will be presented and will be compared in terms of analytical figures of merit. First applications for detection of biomarkers in animal and human tissue samples will be presented.
In a first example, we have applied LA-ICP-MS to visualize the local distribution of proteins, which are used as bio-markers for neurodegenerative diseases. For this purpose, brain tissues from mice experiments have been stained by metal-tagged antibodies. House-keeping proteins have been investigated as internal cellular standards. Additionally, ink-jet printing of metal doped inks onto the surface of tissue samples has been applied for drift corrections and quantification. Validation of our results are achieved in comparison to immune-histochemical staining and optical microscopy.
In a second example, we used specific metal-tagged antibodies for detection of biomarker specific for prostate cancer. For this purpose, micro tissue arrays are incubated with metal-tagged antibodies for bioimaging of samples from many patients using simultaneous detection of all relevant biomarkers and their tags.
For improvement of sensitivity in the next example application nanoparticle tagged antibodies for detection of metallothionines in eye lens tissue samples will be discussed.
Recently we have used our tagging and staining strategies to determine the cell cycle of single cells, which is of future interest for toxicological studies.
Finally, future trends in elemental microscopy and mass cytometry imaging will be discussed.
Die Spurenfeuchte ist eine wichtige Messgröße bei der Qualitätsbeurteilung von technischen und medizinischen Gasen und muss daher zuverlässig gemessen werden. Der Spurenbereich ist definiert durch einen Wasserdampf-Stoffmengenanteil kleiner als 2600 µmol/mol bzw. einer Frostpunkttemperatur kleiner -10 °C. Eine geeignete Methode für die kontinuierliche Spurenfeuchtemessung stellt das Elektrolyseverfahren bzw. coulometrische Messprinzip dar. Bei diesem Prinzip strömt ein feuchtes Gas über eine hygroskopische Phosphorpentoxid-Schicht, welche kontinuierlich Wasserdampf absorbiert. Durch das Anlegen einer Zersetzungsspannung wird das absorbierte Wasser elektrolysiert und der resultierende Elektrolysestrom korreliert zum Feuchtegehalt im Gas. Neben dem Einfluss von unterschiedlichen Gasen auf das Messverfahren, wurde der Einfluss der Druckfeuchte im Druckbereich von 2 bis 15 bar untersucht. Des Weiteren wurde eine neuartige Sensorbeschichtung basierend auf einer ionischen Flüssigkeit getestet und es wurde ein Prototyp für die abgestufte Bestimmung der Wasseraktivität und der Materialfeuchte aufgebaut.
The interaction of nanoparticles (NPs) with cells has become a major field of interest, ranging from medical applications to nanotoxicology. Size, shape and surface modification of the NPs determine the uptake rate and pathway into the cells, and therefore impact specific cell components and processes.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is an established quantitative multi-elemental analysis and mapping technique. In recent years, it was shown that LA-ICP-MS can provide quantitative as well as distribution information of NPs in cell samples.
Here LA-ICP-MS was applied for the imaging of individual cells to study the uptake and intracellular processing of metal-containing nanostructures. Additionally, the local distribution of naturally occurring elements in cells like P was measured to indicate cell morphology. The cells were incubated with different types of NPs under varying experimental conditions. For LA analysis, the cells were fixed and dried.
Our findings show, that LA-ICP-MS is suitable for the localisation of nanoparticle aggregates within cellular compartments. The studied NPs accumulate in the perinuclear region in the course of intracellular processing, but do not enter the cell nucleus. The uptake efficiency depends strongly on the physicochemical properties of the nanostructures as well as on the incubation conditions like concentration and incubation time.
The results demonstrate the potential of LA-ICP-MS providing insight into NP uptake, intracellular distribution and cell-to-cell variation dependent on experimental parameters.
The departure from the current automation landscape to next generation automation concepts for the process industry has already begun. Smart functions of sensors simplify their use and enable plug-and-play integration, even though they may appear to be more complex at first sight. Monitoring specific information (i.e., “chemical” such as physico-chemical properties, chemical reactions, etc.) is the key to “chemical” process control. Here we introduce our smart online NMR sensor module provided in an explosion proof housing as example.
Due to NMR spectroscopy as an “absolute analytical comparison method”, independent of the matrix, it runs with extremely short set-up times in combination with “modular” spectral models. Such models can simply be built upon pure component NMR spectra within a few hours (i.e., assignment of the NMR signals to the components) instead of tedious calibrations runs. We present a range of approaches for the automated spectra analysis moving from statistical approach, (i.e., Partial Least Squares Regression) to physically motivated spectral models (i.e., Indirect Hard Modelling and Quantum Mechanical calculations).
Based on concentration measurements of reagents and products by the NMR analyzer a continuous production and direct loop process control were successfully realized for several validation runs in a modular industrial pilot plant and compared to conventional analytical methods (HPLC, near infrared spectroscopy). The NMR analyser was developed for an intensified industrial process funded by the EU’s Horizon 2020 research and innovation programme (“Integrated CONtrol and SENsing”, www.consens-spire.eu).
Due to NMR spectroscopy as an “absolute analytical comparison method”, independent of the matrix, it runs with extremely short set-up times in combination with “modular” spectral models. Such models can simply be built upon pure component NMR spectra within a few hours (i.e., assignment of the NMR signals to the components) instead of tedious calibrations runs. We present a range of approaches for the automated spectra analysis moving from statistical approach, (i.e., Partial Least Squares Regression) to physically motivated spectral models (i.e., Indirect Hard Modelling and Quantum Mechanical calculations). The departure from the current automation landscape to next generation automation concepts for the process industry has already begun. Smart functions of sensors simplify their use and enable plug-and-play integration, even though they may appear to be more complex at first sight. Monitoring specific information (i.e., “chemical” such as physico-chemical properties, chemical reactions, etc.) is the key to “chemical” process control. Here we introduce our smart online NMR sensor module provided in an explosion proof housing as example.Based on concentration measurements of reagents and products by the NMR analyzer a continuous production and direct loop process control were successfully realized for several validation runs in a modular industrial pilot plant and compared to conventional analytical methods (HPLC, near infrared spectroscopy). The NMR analyser was developed for an intensified industrial process funded by the EU’s Horizon 2020 research and innovation programme.
The departure from the current automation landscape to next generation automation concepts for the process industry has already begun. Smart functions of sensors simplify their use and enable plug-and-play integration, even though they may appear to be more complex at first sight. Monitoring specific information (i.e., “chemical” such as physico-chemical properties, chemical reactions, etc.) is the key to “chemical” process control. Here we introduce our smart online NMR sensor module provided in an explosion proof housing as example.
Due to NMR spectroscopy as an “absolute analytical comparison method”, independent of the matrix, it runs with extremely short set-up times in combination with “modular” spectral models. Such models can simply be built upon pure component NMR spectra within a few hours (i.e., assignment of the NMR signals to the components) instead of tedious calibrations runs. We present a range of approaches for the automated spectra analysis moving from statistical approach, (i.e., Partial Least Squares Regression) to physically motivated spectral models (i.e., Indirect Hard Modelling and Quantum Mechanical calculations).
Based on concentration measurements of reagents and products by the NMR analyzer a continuous production and direct loop process control were successfully realized for several validation runs in a modular industrial pilot plant and compared to conventional analytical methods (HPLC, near infrared spectroscopy). The NMR analyser was developed for an intensified industrial process funded by the EU’s Horizon 2020 research and innovation programme (“Integrated CONtrol and SENsing”, www.consens-spire.eu).
The departure from the current automation landscape to next generation automation concepts for the process industry has already begun. Smart functions of sensors simplify their use and enable plug-and-play integration, even though they may appear to be more complex at first sight. Monitoring specific information (i.e., “chemical” such as physico-chemical properties, chemical reactions, etc.) is the key to “chemical” process control.
The talk introduces a smart online NMR sensor module provided in an explosion proof housing as example. This sensor was developed for an intensified industrial process (pharmaceutical lithiation reaction step) funded by the EU’s Horizon 2020 research and innovation programme (www.consens-spire.eu). Due to NMR spectroscopy as an “absolute analytical comparison method”, independent of the matrix, it runs with extremely short set-up times in combination with “modular” spectral models. Such models can simply be built upon pure component NMR spectra within a few hours (i.e., assignment of the NMR signals to the components) instead of tedious calibrations runs.
Industry 4.0, IIoT, or Lab 4.0 will enable us to handle more complex processes in shorter time. Intensified production concepts require for adaptive analytical instruments and control technology to realize short set-up times, modular control strategies. They are based on a digitized Laboratory 4.0.
Ultrasound echo is a widely used NDT technique for determining the internal geometry of structures. Reverse-time migration (RTM) has been recently introduced to NDT applications, as an imaging method for ultrasound data, to overcome some of the limitations (e.g. imaging steeply dipping reflector) experienced by the Synthetic Aperture Focusing Technique (SAFT), the most commonly used imaging algorithm for these measurements.
The standard implementation of RTM also experiences some drawbacks caused by its imaging condition, which is based on the zero-lag of the cross-correlation between source and receiver wavefields and generates high-amplitude low-frequency artifacts. Three alternative imaging conditions, developed for seismic data applications, were tested for their ability to provide better images than the standard cross-correlation: illumination compensation, deconvolution and wavefield decomposition. A polyamide specimen was chosen for the simulation of a synthetic experiment and for real data acquisition. The migrations of both synthetic and real data were performed with the software Madagascar. The illumination imaging condition was able to reduce the low-frequency noise and had a good performance in terms of computing time. The deconvolution improved the resolution in the synthetic tests, but did not showed such benefit for the real experiments. Finally, as for the wavefield decomposition, although it presented some advantages in terms of attenuating the low-frequency noise and some unwanted reflections, it was not able to image the internal structure of the polyamide as well as the cross-correlation did. Suggestions on how to improve the cost-effectiveness of the implementation of the deconvolution and wavefield decomposition were presented, as well as possible investigations that could be carried out in the future, in order to obtain better results with those two imaging conditions.
An overview about different analytical approaches will be presented of how to detect metals in individual biological cells by use of ICP-MS. For this purpose, we are using different sample introduction systems for ICP-MS for detection, imaging and quantification of metals at cellular levels.
By use of laser ablation, we have studied the up-take by and distribution of nanoparticles in single cells. Recently we have developed staining techniques to measure protein and DNA content of cells and identifying the cell status by immunoassays using metal-tagging of antibodies. New research based on cell arrays will be shortly discussed.
Using pneumatic nebulization and microdroplet generation, we have also studied the up-take of nanoparticles and toxic metals as well as essential elements in single cells using different ICP-MS mass spectrometric concepts (sector field instrument, triple-quad instrument, time of flight (CyTOF) instrument).
The different ICP-MS based methods will be compared concerning their analytical figures of merit and their strengths and weaknesses will be evaluated.
An overview about different analytical approaches will be presented of how to detect metals in individual biological cells by use of ICP-MS. For this purpose, we are using different sample introduction systems for ICP-MS for detection, imaging and quantification of metals at cellular levels.
By use of laser ablation, we have studied the up-take by and distribution of nanoparticles in single cells. Recently we have developed staining techniques to measure protein and DNA content of cells and identifying the cell status by immunoassays using metal-tagging of antibodies. New research based on cell arrays will be shortly discussed.
Using pneumatic nebulization and microdroplet generation, we have also studied the up-take of nanoparticles and toxic metals as well as essential elements in single cells using different ICP-MS mass spectrometric concepts (sector field instrument, triple-quad instrument, time of flight (CyTOF) instrument).
The different ICP-MS based methods will be compared concerning their analytical figures of merit and their strengths and weaknesses will be evaluated.
Der Vortrag stellt einige aktuelle Herausforderungen für die Prozessanalytik und mögliche Antworten vor.
Gepulste Raman-Spektrometer akkumulieren das Raman-Signal mit Hilfe schneller optischer Schalter im Picosekunden-Bereich, bevor langlebigere Fluoreszenzanregung entsteht. Damit lassen sich stark fluoreszierende Materialien untersuchen, die bislang nicht zugänglich sind. Eine weitere interessante Entwicklung ist etwa die Shifted excitation Raman difference spectroscopy (SERDS) die besonders für biologische Anwendungen interessant ist.
Flexible, modulare Produktionsanlagen stellen einen vielversprechenden Ansatz für die kontinuierliche Produktion von Fein- und Spezialchemikalien dar. In einem EU-Projekt wurde die Feldintegration eines Online-NMR-Sensormoduls als smartes Modul für die Prozesskontrolle vorangebracht. Dieses Modul basiert auf einem kommerziell erhältlichen Niederfeld-NMR-Spektrometer, welche zurzeit für die Anwendung im Laborbereich erhältlich ist. Für die Feldintegration wurde ein ATEX-zertifiziertes, explosionsgeschütztes Gehäuse entwickelt sowie Automationsschemen für den unbeaufsichtigten Betrieb und für die kalibrierfreie spektrale Datenauswertung erstellt.
Eine sehr gut anwendbare analytische Messtechnik zur Kontrolle der elementaren Zusammensetzung von verschiedensten Materialien ist die laserinduzierte Plasmaspektroskopie (LIPS, engl. LIBS - Laser-induced Breakdown Spectroscopy). Bei der LIBS wird ein kurz gepulster Laser auf eine Probe fokussiert, um ein Leuchtplasma zu erzeugen. Das dabei erzeugte Atomemissionsspektrum ermöglicht eine qualitative und quantitative Analyse der Zusammensetzung der Probe bezüglich praktisch aller Elemente des Periodensystems. In einem aktuellen Projekt wird diese Methode neben anderen zur Online-Analyse von Ackerböden für die ortsspezifischer Bewirtschaftung (Precision Agriculture) weiterentwickelt und bewertet.
In der Berliner Sammlung "Manuscripta Americana" befinden sich Fragmente von Bilderhandschriften, die Alexander von Humboldt 1804 in Mexiko erwarb und der Königlichen Bibliothek schenkte. Die in der frühen Kolonialzeit hergestellten verschiedenartigen Codices waren damals schon nicht mehr an den Orten ihrer ursprünglichen Verwendung. Entsprechend ihres Seltenheitswertes gelangten einzelne Schriftstücke seit der Conquista in die Bestände bedeutender Persönlichkeiten. Hierzu fertigte man auch Abschriften oder Kopien an, oder zerstückelte sogar einzelne Blätter, so dass die Darstellungen auf den abgetrennten Fragmenten oft nur zum Teil abgebildet vorliegen.
Um herauszufinden, ob einige Schriftstücke der "Humboldt Codices" in Bezug zu einander stehen, werden die Dokumente, ihre Symbole und Schriftzeichen und das zur Herstellung verwendete Material miteinander verglichen.
Mit den für die Analyse von Manuskripten bewährten Untersuchungsmethoden werden Papier und Farbmittel identifiziert. Hierzu zählen Raman-, FTIR-, Röntgenfluoreszenz- und VIS- Spektroskopie. Charakteristisch für die Herstellung von schriftlichen Dokumenten in der Kolonialzeit von Amerika ist die Verwendung von indigenem Material wie Papier aus Baumrinde und Pflanzenfarben zusammen mit den aus Europa bekannten Materialien. Geklärt wird, inwieweit neben den bekanntesten Farbstoffen wie Cochenille, Mayablau oder Mischungen mit Tonmineralen auch mineralische Pigmente zum Einsatz kamen.
Vorgestellt werden die auf Tafel 36 in den "Vues des Cordillères et Monuments des Peuples Indigènes de l`Amerique, Voyage de Humboldt et Bonpland" abgebildeten Fragmente. Die hier von Humboldt vorgenommene Zusammenstellung wird mit der Farbpalette der in Berlin archivierten originalen Schriftstücke verglichen. Die Interpretation der Ergebnisse gibt einen Hinweis auf die Zuordnung oder auch Zusammengehörigkeit dieser einzigartigen Dokumente amerikanischer Geschichte. Hierbei wird die Frage aufgeworfen, inwiefern davon auszugehen ist, dass diese mit weiteren Fragmenten in Verbindung gebracht werden können, was für die Beleuchtung der kulturhistorischen Zusammenhänge von großer Bedeutung ist.
The common characterization and identification of pollen is a time-consuming task that mainly relies on microscopic determination of the genus-specific pollen morphology. A variety of spectroscopic and spectrometric approaches have been proposed to develop a fast and reliable pollen identification using specific molecular information. Amongst them, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) shows a high potential for the successful investigation of such complex biological samples. Based on optimized MALDI sample preparation using conductive carbon tape, the application of multivariate statistics (e.g. principal components analysis, PCA) yields an enormous improvement concerning taxonomic classification of pollen species compared to common microscopic techniques.
Since multivariate evaluation of the recorded mass spectra is of vital importance for classification, it’s helpful to implement the applied sequence of standard Matlab functions into a graphical user interface (GUI). In this presentation, a stand-alone application (GUI) is shown, which provides multiple functions to perform fast multivariate analysis on multiple datasets. The use of a GUI enables a first overview on the measured dataset, conducts spectral pretreatment and can give classification information based on HCA and PCA evaluation. Moreover, it can be used to improve fast spectral classification and supports the development of a simple routine method to identify pollen based on mass spectrometry.
Analyse des Tausalzeintrages in Fahrbahndeckenbetone im Kontext der Alkali-Kieselsäure-Reaktion
(2018)
In den letzten Jahren sind im deutschen Bundesautobahnnetz (BAB-Netz) vermehrt AKR-Schäden an Betonfahrbahndecken aufgetreten, die zum Teil zu einer Halbierung ihrer geplanten Nutzungsdauer von 30 Jahren führte. Ursächlich hierfür ist die Verwendung alkaliempfindlicher Gesteinskörnung, die bei gleichzeitiger Anwesenheit von Wasser infolge der Exposition der Fahrbahndecke und dem alkalischen Milieu durch den Einsatz alkalireicher Portlandzemente bei der Betonherstellung zu einer Alkali-Kieselsäure-Reaktion (AKR) führt. Zusätzlich wird der AKR-Schädigungsprozess in Betonfahrbahndecken durch den externen Tausalzeintrag (primär NaCl) im Winter begünstigt. Vor diesem Hintergrund kommt der Ermittlung des Tausalzeintrags in den Fahrbahndeckenbeton eine große Bedeutung zu. Die Analyse des Tausalzeintrags erfolgte bisher ausschließlich nasschemisch an gemahlenen Bohrkernsegmenten. Nachteilig ist hierbei die fehlende differenzierte Betrachtung des Natriumgehaltes im Zementstein und in der Gesteinskörnung. Der alternative Einsatz von LIBS (Laser-induced breakdown spectroscopy) eröffnet in diesem Kontext neue Möglichkeiten. So wird in diesem Beitrag an Hand von Bohrkernen aus einem AKR-geschädigten BAB-Abschnitt exemplarisch die Vorgehensweise bei der LIBS-Analyse zur Ermittlung der Na- und interagierenden Cl-Verteilung an vertikalen Schnittflächen des Bohrkerns aufgezeigt. Da der Tausalzeintrag primär über den Zementstein erfolgt, wurde der verfälschende Na-Grundgehalt der Gesteinskörnung mittels Zementsteinkriteriums (Nutzung unterschiedlichen Ca-Gehalts in Zementstein und Gesteinskörnung) eliminiert. Vergleichend durchgeführte Cl-Mappings mit Mikroröntgenfluoreszenzanalyse (MRFA) belegen die Güte der durchgeführten LIBS-Messungen.
Aber auch bei der Verifizierung der Übertragbarkeit der Ergebnisse der zum Ausschluss reaktiver Gesteinskörnung bei Neubau und Erneuerung im BAB-Netz eingesetzten Performanceprüfungen mit externem Alkalieintrag auf Praxisverhältnisse hat sich das LIBSVerfahren bewährt. So wurde festgestellt, dass die mit NaCl-Lösung beaufschlagten Laborprüfkörper aus einem repräsentativen Fahrbahndeckenbeton bei der Klimawechsellagerung (KWL) über ihre gesamte Höhe von 10 cm einen Eintrag von Na und Cl erfahren. Weiterhin konnte im Gegensatz zu bisherigen Annahmen erstmals mit LIBS und Nasschemie gezeigt werden, dass die Frost-Tauwechsel-Phase bei der KWL zu keinem erhöhten Tausalzeintrag führt.
In chemical elements with three or more stable isotopes, mass-dependent stable isotope fractionation is expressed by co-varying isotope ratios. In the three-isotope space ((δ’m2/δ’m1)/(( δ’m3/δ’m1)) these plot along a line with a slope (β), the so called ‘terrestrial fractionation line’. This partitioning of stable isotopes results from both kinetic and equilibrium reactions that are characterized by specific β-values.
For the natural range of isotope ratios of ‘novel’ stable isotope systems such as Si, Mg, Fe, Zn, Cu this information cannot be accessed because samples fall close to the delta-zero standard where the current measurement precision is too low to resolve small differences in β. We present a new approach to resolve deviations from a reference slope β by standard-sample bracketing against material offset from the natural range. We use this approach to explore the isotope fractionation mechanism in the mammalian food web. We have analyzed Mg stable isotope ratios in bone bioapatite of herbivore, omnivore and carnivore mammals. Positive shifts in δ26/24Mg along the trophic chain (from herbivore to carnivore) together with β= 0.513 suggest the presence of two isotope fractionation mechanisms operating during biomineralization. While positive shifts in δ26/24Mg are in favor of equilibrium isotope fractionation process, the proximity of β to the theoretically calculated β(kinetic) of typically 0.511 suggests the presence of a second component that fractionates stable isotopes kinetically. The herein presented approach is applicable to any element with 3+ stable isotopes analyzed by multi-collector inductively coupled plasma mass spectrometry.
This is the first time that PE frits were used to quantify sulfur in copper and its alloys by isotope dilution combined with LA-ICP-MS: an alternative approach for sample preparation. The following properties of the PE frit meet the requirements for isotope dilution LA-ICPMS:: porous material, thermo plastic (melting point >100oC), chemical resistance (nitric acid >70%) and high adsorption efficiency. The breakthrough, however, as a support material, especially when comparing the PE frit with other materials such gelatin or sodium silicate is the low blank, which is only two times of the gas flow blank (2.3-4.0 x 104 cps). Additionally, the porosity of the frit was considered, as it directly affects the adsorption efficiency for the sample solution, which is present in the cavities of the frit.
Adsorption efficiency was studied by depositing sulfur standards with varying sulfur amounts (0, 2, 5, 10, 20, 40 and 80 µg S) on the frits. The remaining sulfur which was not absorbed by the frit was rinsed off and was measured by ICP-MS. This indirect method shows that more than 99.5 % of the loaded sulfur was absorbed by the frit. Such high absorption efficiency is completely sufficient for a support material to be used in LA-ICP-IDMS. The so prepared frits whith increasing sulfur amount were measured by LA-ICP-MS showing a good linearity between 0 µg S and 40 µg S whit a correlation coefficient r2 of 0.9987 and sensitivy of 3.4x104 cpsµg-1 for 32S.
Three copper reference materials produced by BAM were selected to develop and validate the LA-ICP-IDMS procedure. The IDMS technique was applied to these samples as follows: the samples were spiked, dissolved, digested and then the digest was adsorbed on the frits.
Summary: A screening test for potential emissions of volatile organic compounds (VOC) was run on different thermoplastic filaments used for 3D printing. The method of direct thermal desorption was used to simulate the high temperatures during the 3D printing process and to identify the main compounds emitted from the filaments. A large number of unexpected compounds were detected that might affect the user’s health and have an impact on indoor air chemistry.
Introduction: The use of desktop 3D printers is increasing. Compared to other devices with known emissions, e.g. laser printers, there is still a lack of information on possible emissions of VOC and ultrafine particles during operation and the effect on indoor air quality. Most of the commercially available desktop 3D printers operate with a molten polymer deposition. For this process a solid thermoplastic filament is heated in an extrusion nozzle. Most filaments for desktop 3D printers use either acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) as filament. Alternatives are polyvinyl alcohol (PVA) or polycarbonate (PC).
Method: Eight different thermoplastic filaments for 3D printers were analysed by direct thermal desorption followed by GC-MS identification of the emitted substances. Direct thermal desorption was done by desorbing 5 mg of the feedstock for 1 minute at a temperature of 210°C. This is an average temperature for 3D printing with thermoplastic filaments.
Results and conclusions: The comparison of the 4 different filament groups showed the highest overall emissions from ABS, followed by PLA, PC and PVA. Filament ABS 2 emitted mainly SVOCs and triphenyl phosphate, the latter has the highest emission for a single compound from all evaluated filaments.
Thermoplastic filaments are a new source of VOC emissions due to the high temperatures associated with 3D printing, which can reach up to 270°C. Some of the detected compounds like lactic acid, lactide and bisphenol A have never been described before in the indoor environment. Additionally some of the main substances could not be identified and some others might have the potential to affect the indoor air chemistry.
The appearance of some newly detected compounds raises concerns about potential health effects for the users of 3D printers at home.
Non-invasive Cereal Analysis by GC-MS detection of Trichodiene as a Volatile Mycotoxin Biomarker
(2018)
Due to the increasing consumption of cereals worldwide, the monitoring of growth, storage and processing is becoming more and more crucial. Particularly when stored, infested grains breed fungal clusters (“hot spots”) in which mycotoxins greatly exceed allowed maximum levels. Because of their unpredictable presence, current sample drawing and procedures for mycotoxin analysis represent a complex challenge for operators, involving invasive and cost intensive steps.
Therefore, new time- and labour-saving mycotoxin control methods including sampling and analysis steps are needed. A possible approach is the non-invasive analysis of the homogeneous gas phase above the crops, instead of analyzing random samples. However, this procedure requires microbial volatile organic compounds (MVOC´s) being released by the samples and representing the present mycotoxins. Previous investigations revealed trichodiene to be a precursor in trichothecenes biosynthesis – one of the largest mycotoxin groups with over 180 compounds. Due to its non-functionalized sesquiterpene structure, trichodiene has already been quantified using Headspace GC-MS methods (for instance). Thereby, it can possibly be used as a biomarker for trichothecene contamination in foodstuff.
However, further investigations are necessary. The correlation between trichodiene concentration in the gas phase and trichothecenes mass fraction in the sample must be examined closely to draw conclusions about the exact trichothecene content within samples. Realizing this idea, would widely extend the applicability of trichodiene and enormously simplify trichothecene quantification. Hence, this first step of an ongoing study aims to develop a laboratory reference method using trichodiene as volatile biomarker to quantify trichothecenes in cereals. Static headspace and SPME-enrichment coupled to gas chromatography with mass spectrometry (GC-MS) were employed. In a second step, this reference method is intended to validate new approaches for fast on-site screening of trichodiene in cereals.
Heritage Lecture
(2018)
After finishing my diploma thesis in plasma physics in 1981, I dreamt of a future in a research lab to develop novel fusion reactors for energy production or to study universal plasmas and their emission in the cosmos. This dream never became real, however I found my first job in a team to build up a new museum dedicated to “Energy”, and this first part of my career was already finished after a year, because the funding was not extended. So, I found immediately a new job as a young scientist in the institute for analytical sciences (originally ISAS: Institute for Plasmachemistry and Applied Spectroscopy) in 1982 to develop novel plasma ion sources for inorganic mass spectrometry. The first source of interest was based on a glow discharge for direct analysis of conducting solids (technically supported by Finnigan MAT, Bremen). Here I adopted the design of the Grimm type discharge for the first time, which was well known in optical emission spectroscopy, and coupled it to a quadrupole mass analyzer. The advantage of this design was that flat craters are produced by sputtering which made this source very powerful for in-depth analysis of technical layers. This then became the topic of my PhD, which was not originally planned, and I had to learn a lot about surface analysis. However, since the first project was too successful we established a small team (in cooperation with Jose Broekaert - an expert in ICP-OES) which started with the development of our own inductively coupled plasma ion source in 1986 coupled to a quadrupole and in 1989 to a sector field mass spectrometer (funded by the Minister of Science and Technology; again in cooperation with Finnigan MAT). The latter device was launched to the market in 1993 as the Element 1.
The second decade of my career was still related to instrumental development but mainly of glow discharge sources. In an EU funded project first an automated glow discharge sector field instrument was developed where the Grimm type geometry was combined with a fast flow concept (in cooperation with Volker Hoffmann at IFW in Dresden). This was done in cooperation with VG (which became later a part of Thermo Fisher Scientific together with Finnigan MAT), so that it is not surprising that this concept for the Element GD. This project was later continued in the third phase of my career, again funded by the EU and in cooperation with the group of Alfredo Sanz-Medel (Rosario Pereiro and Jorge Pisonero), to develop a fast flow, but now rf-powered GD ion source in combination with a time-of-flight mass spectrometer, which was later launched to the market commercially by Horiba Jobin Yvon (France) for in-depth profiling of thin layers even of non-conducting materials.
In the first decade of my career I started to study already “analytical chemistry” from the scratch because the instruments developed have been applied now for direct analysis of solid materials, technical layers and environmental samples. In case of environmental applications our ICP-MS (the quadrupole and the sector field instrument) was coupled with separation techniques, so that this period of instrumental development was dominated in the second decade by development of high efficiency sample introduction systems in combination with speciation studies of Pt group elements, arsenic, selenium and phosphorus (in DNA and phosphorylated proteins), Ni and Cr. Additionally, we continued with the analysis of solid ceramic materials (Al2O3, SiC, SiN) and ambient air-born particles. At the end of the second decade we complemented our instrumental pool by a collision and reaction cell instrument in cooperation with Micromass and used this instrument for speciation studies of peptides and proteins and demonstrated that by ICP-HEX-MS quantitative proteomics is feasible. Therefore, we more and more focused in the following years on metalloproteins and published a famous paper on “Metallobiomolecules: The basis of life, the challenge of atomic spectroscopy” (together with Luc Moens and Ryszard Lobinski). For detection of metalloproteins we applied typical workflows of biochemistry and proteomics, for which I had to extend my knowledge about biochemistry and proteomics. As a new analytical tool, we used a homemade laser ablation cell for sample introduction of metalloproteins after their separation by gel electrophoresis and extended this work by applying metal-tagging of antibodies for Western blot assays. For this purpose, proteins were separated in SDS-PAGE and electroblotted onto membranes. Specific detection of proteins even not containing any metal could be performed by laser ablation ICP-MS using the metal tagged antibodies for indirect detection. This research was interrupted in 2009 by a movement from ISAS (where atomic spectroscopy was declining) to BAM (the Federal Institute for Materials Research and Testing, Berlin) where this research direction was fostered. The experience we achieved at ISAS in the previously mentioned projects were now used here at BAM in the fourth decade for materials research and the development of a quantitative elemental microscope with cellular resolution. So, at the end of my career I am trying to apply all my knowledge and expertise to develop analytical methods and to apply multimodal spectroscopies to decipher the construction code of the cellular machinery, which is the most precise and complex machinery I have ever seen. If we were able to understand how this machinery works, we can better diagnose and treat a malfunction in case of the development of a disease.
Finally, I can conclude that lifelong learning starts before school but does not end at the end of this lecture. It looks like this heritage lecture will be focused on my career only, but this is not the case because some highlights of my career will be used to illustrate a few universal principles: how to have fun, how to find friends and how this all leads to an increase of joy and joy is the basis of new ideas (which must not always be related to your profession) and novel ideas are essential for a successful and satisfying career. So, this heritage lecture wants to answer the most important question of a life which was dedicated to plasma spectrochemistry:
1) Is it possible - at all - to have fun in this research direction?
2) Can we learn already today what we need tomorrow?
3) How can we still realize our scientific dreams of cutting edge research in times of cutting budgets? Which automatically leads to the next question:
4) Is necessity the mother of invention?
All questions will be answered! Controversial discussions (for angry or disappointed colleagues) will be stimulated and my visions of future research (for students and postdocs) and instrumental developments (for manufacturer) will be presented. Finally, conclusions will be drawn by the auditorium (everybody) and thanks will be given to Ramon Barnes (by me) already in advance!
Heritage Lecture
(2018)
After finishing my diploma thesis in plasma physics in 1981, I dreamt of a future in a research lab to develop novel fusion reactors for energy production or to study universal plasmas and their emission in the cosmos. This dream never became real, however I found my first job in a team to build up a new museum dedicated to “Energy”, and this first part of my career was already finished after a year, because the funding was not extended. So, I found immediately a new job as a young scientist in the institute for analytical sciences (originally ISAS: Institute for Plasmachemistry and Applied Spectroscopy) in 1982 to develop novel plasma ion sources for inorganic mass spectrometry. The first source of interest was based on a glow discharge for direct analysis of conducting solids (technically supported by Finnigan MAT, Bremen). Here I adopted the design of the Grimm type discharge for the first time, which was well known in optical emission spectroscopy, and coupled it to a quadrupole mass analyzer. The advantage of this design was that flat craters are produced by sputtering which made this source very powerful for in-depth analysis of technical layers. This then became the topic of my PhD, which was not originally planned, and I had to learn a lot about surface analysis. However, since the first project was too successful we established a small team (in cooperation with Jose Broekaert - an expert in ICP-OES) which started with the development of our own inductively coupled plasma ion source in 1986 coupled to a quadrupole and in 1989 to a sector field mass spectrometer (funded by the Minister of Science and Technology; again in cooperation with Finnigan MAT). The latter device was launched to the market in 1993 as the Element 1.
The second decade of my career was still related to instrumental development but mainly of glow discharge sources. In an EU funded project first an automated glow discharge sector field instrument was developed where the Grimm type geometry was combined with a fast flow concept (in cooperation with Volker Hoffmann at IFW in Dresden). This was done in cooperation with VG (which became later a part of Thermo Fisher Scientific together with Finnigan MAT), so that it is not surprising that this concept for the Element GD. This project was later continued in the third phase of my career, again funded by the EU and in cooperation with the group of Alfredo Sanz-Medel (Rosario Pereiro and Jorge Pisonero), to develop a fast flow, but now rf-powered GD ion source in combination with a time-of-flight mass spectrometer, which was later launched to the market commercially by Horiba Jobin Yvon (France) for in-depth profiling of thin layers even of non-conducting materials.
In the first decade of my career I started to study already “analytical chemistry” from the scratch because the instruments developed have been applied now for direct analysis of solid materials, technical layers and environmental samples. In case of environmental applications our ICP-MS (the quadrupole and the sector field instrument) was coupled with separation techniques, so that this period of instrumental development was dominated in the second decade by development of high efficiency sample introduction systems in combination with speciation studies of Pt group elements, arsenic, selenium and phosphorus (in DNA and phosphorylated proteins), Ni and Cr. Additionally, we continued with the analysis of solid ceramic materials (Al2O3, SiC, SiN) and ambient air-born particles. At the end of the second decade we complemented our instrumental pool by a collision and reaction cell instrument in cooperation with Micromass and used this instrument for speciation studies of peptides and proteins and demonstrated that by ICP-HEX-MS quantitative proteomics is feasible. Therefore, we more and more focused in the following years on metalloproteins and published a famous paper on “Metallobiomolecules: The basis of life, the challenge of atomic spectroscopy” (together with Luc Moens and Ryszard Lobinski). For detection of metalloproteins we applied typical workflows of biochemistry and proteomics, for which I had to extend my knowledge about biochemistry and proteomics. As a new analytical tool, we used a homemade laser ablation cell for sample introduction of metalloproteins after their separation by gel electrophoresis and extended this work by applying metal-tagging of antibodies for Western blot assays. For this purpose, proteins were separated in SDS-PAGE and electroblotted onto membranes. Specific detection of proteins even not containing any metal could be performed by laser ablation ICP-MS using the metal tagged antibodies for indirect detection. This research was interrupted in 2009 by a movement from ISAS (where atomic spectroscopy was declining) to BAM (the Federal Institute for Materials Research and Testing, Berlin) where this research direction was fostered. The experience we achieved at ISAS in the previously mentioned projects were now used here at BAM in the fourth decade for materials research and the development of a quantitative elemental microscope with cellular resolution. So, at the end of my career I am trying to apply all my knowledge and expertise to develop analytical methods and to apply multimodal spectroscopies to decipher the construction code of the cellular machinery, which is the most precise and complex machinery I have ever seen. If we were able to understand how this machinery works, we can better diagnose and treat a malfunction in case of the development of a disease.
Finally, I can conclude that lifelong learning starts before school but does not end at the end of this lecture. It looks like this heritage lecture will be focused on my career only, but this is not the case because some highlights of my career will be used to illustrate a few universal principles: how to have fun, how to find friends and how this all leads to an increase of joy and joy is the basis of new ideas (which must not always be related to your profession) and novel ideas are essential for a successful and satisfying career. So, this heritage lecture wants to answer the most important question of a life which was dedicated to plasma spectrochemistry:
1) Is it possible - at all - to have fun in this research direction?
2) Can we learn already today what we need tomorrow?
3) How can we still realize our scientific dreams of cutting edge research in times of cutting budgets? Which automatically leads to the next question:
4) Is necessity the mother of invention?
All questions will be answered! Controversial discussions (for angry or disappointed colleagues) will be stimulated and my visions of future research (for students and postdocs) and instrumental developments (for manufacturer) will be presented. Finally, conclusions will be drawn by the auditorium (everybody) and thanks will be given to Ramon Barnes (by me) already in advance!
qNMR provides the most universally applicable form of direct concentration or purity determination without need for reference materials of impurities or the calculation of response factors but only exhibiting suitable NMR properties.
The workshop presents basic terms of statistics and uncertainty analysis, which are the basis for qNMR spectroscopy and data analysis such as, e.g., standard deviations, linear regression, significance tests, etc. and gives typical examples of applications in qNMR spectroscopy.
The departure from the current automation landscape to next generation automation concepts for the process industry has already begun. Smart functions of sensors simplify their use and enable plug-and-play integration, even though they may appear to be more complex at first sight. Monitoring specific information (i.e., “chemical” such as physico-chemical properties, chemical reactions, etc.) is the key to “chemical” process control.
The talk introduces a smart online NMR sensor module provided in an explosion proof housing as example. This sensor was developed for an intensified industrial process (pharmaceutical lithiation reaction step) funded by the EU’s Horizon 2020 research and innovation programme (www.consens-spire.eu). Due to NMR spectroscopy as an “absolute analytical comparison method”, independent of the matrix, it runs with extremely short set-up times in combination with “modular” spectral models. Such models can simply be built upon pure component NMR spectra within a few hours (i.e., assignment of the NMR signals to the components) instead of tedious calibrations runs.
The talk also generally covers current aspects of high-field and low-field online NMR spectroscopy for reaction monitoring and process control and gives also an overview on direct dissolution studies of API cocrystals.
Hydrogen determination in weld seams is standardized in ISO 3690. In accordance to this standard, a defined time for hydrogen collection has to be anticipated for different extraction temperatures. In other words, the temperature is the most important value that has to be monitored in addition to the aimed hydrogen determination.
The specimen geometry has influence on the real sample temperature during CGHE vs. the adjusted furnace temperature. This presentation gives a short summary on possible influences on the "correct" hydrogen determination temperature during carrier gas hot extraction (CGHE) using infrared radiation driven furnace. The main findings are: (1) specimen surface is important in terms of polished or oxidized condition, (2) specimen geometry is important for fast heating, (3) PID-values of control software are a considerable influence to accelerate the heating process depite thick specimens and (4) independent sample temperature determination before CGHE is strongly recommended.
Mykotoxine werden als sekundäre Metabolite von Schimmelpilzen gebildet und haben diverse schädliche Effekte auf Menschen, Tiere und Pflanzen. Laut FAO sind weltweit bis zu 25 % aller Lebens- und Futtermittel mit Mykotoxinen kontaminiert, wodurch jährlich immense ökonomische Verluste entstehen.
Neben den eigentlichen Mykotoxinen rücken zunehmend deren Transformationsprodukte (TPs) in den Fokus. Diese können als natürliche Stoffwechselprodukte toxischer sein als das eigentliche Mykotoxin und stellen eine potenzielle zusätzliche Gefahr für den Verbraucher dar. TPs werden überwiegend mit in vitro und in vivo Techniken untersucht, welche sowohl zeit- als auch kostenintensiv sind. Ziel war es nun, schnelle und zudem verlässliche Techniken zur Simulation von TPs diverser Mykotoxine zu testen. Die Kopplung von Elektrochemie und Massenspektrometrie, kurz EC/MS, als rein instrumenteller Ansatz ist seit vielen Jahren in der pharmazeutischen Forschung etabliert. Hierbei wird mithilfe einer elektrochemischen Durchflusszelle der oxidative Metabolismus einer Substanz simuliert und zugleich analysiert.
Unter Verwendung von EC/MS, EC/LC/MS und HPLC-MS Techniken (MS/MS und FT-ICR) wurden nun die Mykotoxine Zearalenon, Citrinin und Dihydroergocristin (als Modellsubstanz für die Ergotalkaloide) elektrochemisch bei Potentialen bis zu 2500 mV vs. Pd/H2 oxidiert und deren TPs mit mikrosomalen in vitro Ansätzen verglichen. Hierbei konnten mehrere Übereinstimmungen hydroxylierter Spezies, sowohl elektrochemisch als auch biochemisch generiert, festgestellt werden. Die EC/MS ist somit auch in der Lebensmittelanalytik als nützliches und vielseitiges Werkzeug verwendbar.
Quantifizierung der Schädigung von DNA in wässriger Lösung unter direkter Elektronenbestrahlung
(2018)
To cure cancer radiation therapy is used to kill tumor cells.
It is based on radiation induced damage to biomolecules.
Especially DNA damage is of key interest due to its central role in apoptosis and mutation.
Because of the high amount of water in biological tissue, most of the damage is caused by the secondary particles produced by the inelastic scattering of ionizing radiation and water.
A detailed understanding of the underlying molecular processes under physiological conditions is the prerequisite to develop more efficient therapies.
Goal of this work is to quantify the DNA damage caused by ionizing radiation in dependence of the inelastic scattering events and the energy deposit within the microscopic target volume of biological relevance.
The irradiations have to be performed in liquid, under consideration of the chemical environment.
Therefore, a new combination of experiment and Monte-Carlo simulations was developed and tested.
To make it possible to irradiate liquids with electrons within scanning electron microscopes a new sample holder was constructed incorporating an electron transparent nanomembrane.
It makes it possible to irradiate DNA, proteins or cells at different pH, salinity and in the presence of cosolutes.
%The most important results of this work are as follows:
The median lethal dose for a model system of plasmid DNA and water was determined by the combination of experimental data, particle scattering simulations (Geant4-DNA) and diffusion calculations as D0.5=(1.7+-0.3) Gy.
From the convolution of plasmid positions and the spatially resolved energy deposit, as determined by electron scattering simulations, the histogram of the energy deposit within the target volume of the plasmids and the microscopic median lethal energy deposit was calculated as E0.5=6+-4eV.
It could be deduced that on average less than two ionization events are sufficient to cause a single-strand-break.
The relation of single-strand-breaks (SSB) to double-strand-breaks (DSB), which is of importance for microdosimetric modeling, was determined as SSB:DSB = 12:1.
The presented method for the determination of microscopic dose-damage relations was further extended to be applicable for general irradiation experiments.
It becomes independent of the type of primary radiation used, the experimental geometry, and the diffusional properties of the molecules under investigation.
This way different experimental systems with varying, inhomogeneous energy deposit characteristics become comparable with each other, which is not possible when only macroscopic averaged values are taken into account.
In addition, the radiation protection properties of the compatible solute ectoine, as well as its influence on the water properties and biomolecules were investigated.
%In addition, the influence of the compatible solute ectoine on water, biomolecules and its radiation protection properties were investigated.
Raman spectroscopy revealed a concentration dependent increase of the collective water modes in the OH-stretching region, which was found to be independent of the sodium chloride concentration.
Molecular dynamic simulations showed that the zwitterionic properties of ectoine lead to its half-chair conformation.
The hydrogen bonds in the first hydration shell are more stable and have an increased lifetime compared to the bulk water.
Irradiation experiments with DNA in the presence of 1M ectoine revealed an increase of the survival rate by a factor of 1.41 as compared to the absence of ectoine.
The protective properties of ectoine result from the increase of the inelastic scattering probabilities of low energy electrons at the acoustic vibrational modes of water and its properties as OH-radical scavenger.
This was shown by Raman spectroscopy and electron paramagnetic resonance measurements (EPR).
The overall interest in nanotoxicity, triggered by the increasing use of nanomaterials in the material and life sciences, and the synthesis of an ever increasing number of new functional nanoparticles calls for standardized test procedures1,2 and for efficient approaches to screen the potential genotoxicity of these materials. Aiming at the development of fast and easy to use, automated microscopic methods for the determination of the genotoxicity of different types of nanoparticles, we assess the potential of the fluorometric γH2AX assay for this purpose. This assay, which can be run on an automated microscopic detection system, relies on the detection of DNA double strand breaks as a sign for genotoxicity3. Here, we provide first results obtained with broadly used nanomaterials like CdSe/CdS and InP/ZnS quantum dots as well as iron oxide, gold, and polymer particles of different surface chemistry with previously tested colloidal stability and different cell lines like Hep-2 and 8E11 cells, which reveal a dependence of the genotoxicity on the chemical composition as well as the surface chemistry of these nanomaterials. These studies will be also used to establish nanomaterials as positive and negative genotoxicity controls or standards for assay performance validation for users of this fluorometric genotoxicity assay. In the future, after proper validation, this microscopic platform technology will be expanded to other typical toxicity assays.