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This study shows remarkably different features between the oxidation of secondary and primary C₃-C₅ alcohols. The oxidation of primary alcohols is controlled by the oxidative removal of blocking adsorbates, such as CO, formed after the dissociative adsorption of alcohol molecules. Conversely, secondary alcohols do not undergo dissociative adsorption and therefore their oxidation is purely controlled by the energetics of the elementary reaction steps. In this respect, a different role of ruthenium is revealed for the electrooxidation of primary and secondary alcohols on bimetallic platinum-ruthenium catalysts. Ruthenium enhances the oxidation of primary alcohols via the established bifunctional mechanism, in which the adsorption of (hydr)oxide species that are necessary to remove the blocking adsorbates is favored. In contrast, the oxidation of secondary alcohols is enhanced by the Ru-assisted stabilization of an O-bound intermediate that is involved in the potential-limiting step. This alternative pathway enables the oxidation of secondary alcohols close to the equilibrium potential.
Assessing dissolution of upconverting nanoparticles by TEM, EDXS, potentiometry and fluorometry
(2021)
Inorganic lanthanide-doped upconversion nanoparticles (UCNP) constitute an emerging class of near-infrared (NIR)-excitable luminescent reporters for bioimaging, fluorescence assays, sensors in bioanalysis, and optical thermometry as well as phosphors for photovoltaic and security applications.1 However, the use of UCNPs in bioimaging and cellular studies requires biocompatible particles. One possible cause of UCNP toxicity is the release of potentially harmful fluoride fluoride and lanthanide ions as revealed by dilution studies in aqueous environments, particularly under high dilution conditions.2-5 To address this issue, suitable surface coatings preventing such effects in combination with fast screening methods suited for online in situ analysis are desired.
Here we present a systematic study of differently sized β-NaYF4:Yb,Er nanocrystals stabilized with different surface coatings and different hydrophilic ligands varying in binding strength to the surface atoms in various aqueous environments at different temperatures.
Optical Stability Studies of Hexagonal Upconverting Nanocrystals and Development of Monitoring Tools
(2021)
We demonstrate the potential of time-resolved luminesence spectroscopy for the straightforward assessment and in situ monitoring of the stabilty of UCNPs. Different analytical methods were used to assess the dissolution behaviour of UCNPs in varuous media. Potentiometric and optical data were correlated to develop a new non-invasive monitoring tool for particle dissolution
Engineered nanomaterials (NM) with their unique size-dependent properties are of increasing relevance for current and future developments in various fields such as medical and pharmaceutical industry, computing and electronics or food and consumer products. The performance and safety of NM are determined by the sum of their intrinsic physicochemical properties. Especially, the particle surface chemistry, which is largely controlled by the chemical nature and density of functional groups and ligands, is an important key driver for the performance, stability, and processibility of NM, as well as their interaction with the environment. Thus, methods for functional group quantification can foster the sustainable development of functional and safe(r) NM.
Aiming at the development of simple, versatile and multimodal tools for the quantification of common bioanalytically relevant functional groups, we designed a catch-and-release assay based on cleavable probes that enable the quantification of the cleaved-off reporters in the supernatant after particle separation. Thus, the approach circumvents interferences resulting from particle light scattering and sample-inherent absorption or emission. To study the potential of the assay, commercially available and in-house synthesized aminated and carboxylated polymer and silica nanoparticles of different functional group densities were tested.
Our cleavable probe strategy can be easily adapted to other analytical techniques requiring different reporters, or to different types of linkers that can be cleaved thermally, photochemically, or by variation of pH, utilizing well-established chemistry. In addition, it can contribute to the development of multi-method characterization strategies to provide a more detailed picture of the intrinsic physicochemical property - performance/safety relationships and thus can support the design of tailored nanomaterials with better controlled properties.
Mass Spectrometry (MS) and Nuclear Magnetic Resonance Spectroscopy (NMR) are critical components of every industrial chemical process as they provide information on the concentrations of individual compounds and by-products. These processes are carried out manually and by a specialist, which takes a substantial amount of time and prevents their utilization for real-time closed-loop process control. This paper presents recent advances from two projects that use Artificial Neural Networks (ANNs) to address the challenges of automation and performance-efficient realizations of MS and NMR. In the first part, a complete toolchain has been developed to develop simulated spectra and train ANNs to identify compounds in MS. In the second part, a limited number of experimental NMR spectra have been augmented by simulated spectra to train an ANN with better prediction performance and speed than state-of-theart analysis. These results suggest that, in the context of the digital transformation of the process industry, we are now on the threshold of a possible strongly simplified use of MS and MRS and the accompanying data evaluation by machine-supported procedures, and can utilize both methods much wider for reaction and process monitoring or quality control.
Under the auspices of the Protein Analysis Working Group (PAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) a pilot study, CCQM-P216, was coordinated by the Chinese National Institute of Metrology (NIM), National Research Council of Canada (NRC) and the Bureau International des Poids et Mesures (BIPM). Eleven Metrology Institutes or Designated Institutes and the BIPM participated in the first phase of the pilot study (Part 1). The purpose of this pilot study was to develop measurement capabilities for larger proteins using a recombinant humanized IgG monoclonal antibody against Spike glycoprotein of SARS-CoV-2 (Anti-S IgG mAb) in solution. The first phase of the study was designed to employ established methods that had been previously studies by the CCQM Protein Analysis Working Group, involving the digestion of protein down to the peptide or amino acid level. The global coronavirus pandemic has also led to increased focus on antibody quantitation methods. IgG are among the immunoglobulins produced by the immune system to provide protection against SARS-CoV-2. Anti-SARS-CoV-2 IgG can therefore be detected in samples from affected patients. Antibody tests can show whether a person has been exposed to the SARS-CoV-2, and whether or not they potentially show lasting immunity to the disease. With the constant spread of the virus and the high pressure of re-opening economies, antibody testing plays a critical role in the fight against COVID-19 by helping healthcare professionals to identify individuals who have developed an immune response, either via vaccination or exposure to the virus. Many countries have launched large-scale antibody testing for COVID-19. The development of measurement standards for the antibody detection of SARS-CoV-2 is critically important to deal with the challenges of the COVID-19 pandemic. In this study, the SARS-CoV-2 monoclonal antibody is being used as a model system to build capacity in methods that can be used in antibody quantification. Amino acid reference values with corresponding expanded uncertainty of 36.10 ± 1.55 mg/kg, 38.75 ± 1.45 mg/kg, 18.46 ± 0.78 mg/kg, 16.20 ± 0.67 mg/kg and 30.61 ± 1.30 mg/kg have been established for leucine, valine, phenylalanine, isoleucine and proline, respectively. Agreement between nearly all laboratories was achieved for the amino acid analysis within 2 to 2.5 %, with one participant achieving markedly higher results due to a technical issue found in their procedure; this result was thus excluded from the reference value calculations. The relatively good agreement within a laboratory between different amino acids was not dissimilar to previous results for peptides or small proteins, indicating that factors such as hydrolysis conditions and calibration procedures could be the largest sources of variability. Peptide reference values with corresponding expanded uncertainty of 4.99 ± 0.28 mg/kg and 6.83 ± 0.65 mg/kg have been established for ALPAPIEK and GPSVFPLAPSSK, respectively. Not surprisingly due to prior knowledge from previous studies on peptide quantitation, agreement between laboratories for the peptide-based analysis was slightly poorer at 3 to 5 %, with one laboratory's result excluded for the peptide GPSVFPLAPSSK. Again, this level of agreement was not significantly poorer than that achieved in previous studies with smaller or less complex proteins. To reach the main text of this paper, click on Final Report.
Vergleichende Darstellung SARS-CoV-2-spezifischer Nanobodys aus unterschiedlichen Wirtsorganismen
(2021)
Aufgrund der anhaltenden COVID-19-Pandemie werden neutralisierende Therapeutika benötigt. Eine Möglichkeit zur Behandlung stellt die Verwendung monoklonaler Anti-SARS-CoV-2-Immun-globuline dar. Ihre Produktion in Säugetierzellen ist jedoch schwer skalierbar, um den weltweiten Bedarf zu decken. VHH-Antikörper, auch Nanobodys genannt, bieten hierfür eine Alternative, da sie eine hohe Temperaturstabilität aufweisen und eine kostengünstige Produktion in prokaryotischen Wirtsorganismen ermöglichen.
Development of an affinity-based method for the site-selective synthesis of antibody-drug-conjugates
(2021)
For the site-selective synthesis of ADCs, a variety of obstacles must be overcome. Those include designing bifunctional affinity peptides with reasonably low 𝐾𝑑-values that couple to the mAb in a site-selective manner. These peptides should also include a functional group that links the payload to the mAb under mild conditions without adversely affecting it. The bioconjugation between peptide and antibody and the linker between peptide and payload must be stable and durable to provide safety when used for medical purposes. The usage of metals and organic solvents should be minimized. Within the project, new types of functionalized affinity peptides were designed, and their affinity towards the Fc-fragment was determined.
Recent progress has shown that using wavelengths between 1,000 and 2,000 nm, referred to as the shortwave-infrared or near-infrared (NIR)-II range, can enable high-resolution in vivo imaging at depths not possible with conventional optical wavelengths.
However, few bioconjugatable probes of the type that have proven invaluable for multiplexed imaging in the visible and NIR range are available for imaging these wavelengths. Using rational design, we have generated persulfonated indocyanine dyes with absorbance maxima at 872 and 1,072 nm through catechol-ring and aryl-ring fusion, respectively, onto the nonamethine scaffold. Multiplexed two-color and three-color in vivo imaging using monoclonal antibody and dextran conjugates in several tumor models illustrate the benefits of concurrent labeling of the tumor and healthy surrounding tissue and lymphatics.
These efforts are enabled by complementary advances in a custom-built NIR/shortwave-infrared imaging setup and software package for multicolor real-time imaging.
Der AK 3.7 ist ein "erweiterter" AK und je zur Hälfte mit NAMUR-Vertretern und Vertretern der Geräte- und Softwarehersteller besetzt. Er wurde ins Leben gerufen, um Begrifflichkeiten der digitalen Transformation aufzugreifen, wie etwa Smarte Sensorik, Sensordatenfusion, Schwarmsensorik oder Softsensorik. Eine erste Aufgabe bestand darin, einige exemplarische Anwendungsfälle der Nutzung smarter Eigenschaften von Feldgeräten sowie deren zukünftige Kommunikationsmöglichkeiten sowohl mit Bezug auf Bestandsanlagen als auch mit Blick auf einen potentiellen Technologiewechsel zu betrachten. Neuer Scope des AK 3.7 ist eine "Next Generation Automation" um einen potentiellen Technologiewechsel rechtzeitig vorauszudenken. Dieses erfolgt unter vollständiger gedanklicher Trennung von heutiger Automatisierung und auch vom NOA-Konzept.
Ebenso wird ein Technologiewechsel in der Produktion der Prozessindustrie (wahrscheinlich modulbasiert) postuliert. Ziel des AK 3.7 wird es in Zukunft sein, diese Anforderungen an smarte Feldgeräte aufzugreifen und gemeinsam mit den thematisch überlappenden Interessenskreisen in Standards zu übersetzen.
Increasing contamination of environmental waters with pharmaceuticals represents an emerging threat for the drinking water quality and safety. In this regard, fast and reliable analytical methods are required to allow quick countermeasures in case of contamination. Here, we report the development of a magnetic bead-based immunoassay (MBBA) for the fast and cost-effective determination of the analgesic diclofenac (DCF) in water samples, based on diclofenac-coupled magnetic beads and a robust monoclonal anti-DCF antibody. A novel synthetic strategy for preparation of the beads resulted in an assay that enabled for the determination of diclofenac with a significantly lower limit of detection (400 ng/L) than the respective enzyme-linked immunosorbent assay (ELISA). With shorter incubation times and only one manual washing step required, the assay demands for remarkably shorter time to result (< 45 min) and less equipment than ELISA. Evaluation of assay precision and accuracy with a series of spiked water samples yielded results with low to moderate intra- and inter-assay variations and in good agreement with LC–MS/MS reference analysis. The assay principle can be transferred to other, e.g., microfluidic, formats, as well as applied to other analytes and may replace ELISA as the standard immunochemical method.
The CCQM-K148.a comparison was coordinated by the BIPM on behalf of the CCQM Organic Analysis Working Group for NMIs and DIs which provide measurement services in organic analysis under the CIPM MRA. It was undertaken as a "Track A" comparison within the OAWG strategic plan. CCQM-K148.a demonstrates capabilities for assigning the mass fraction content of a solid organic compound having moderate molecular complexity, where the compound has a molar mass in the range (75 - 500) g/mol and is non-polar (pKow < −2), when present as the primary organic component in a neat organic solid and where the mass fraction content of the primary component in the material is in excess of 950 mg/g.
Participants were required to report the mass fraction of Bisphenol A present in one supplied unit of the comparison material. Participants using a mass balance method for the assignment were also required to report their assignments of the impurity components present in the material. Methods used by the seventeen participating NMIs or DIs were predominantly based on either stand-alone mass balance (summation of impurities) or qNMR approaches, or the combination of data obtained using both methods. The results obtained using thermal methods based on freezing-point depression methods were also reported by a limited number of participants. There was excellent agreement between assignments obtained using all three approaches to assign the BPA content.
The assignment of the values for the mass fraction content of BPA consistent with the KCRV was achieved by most of the comparison participants with an associated relative standard uncertainty in the assigned value in the range (0.1 - 0.5)%.
Intelligent sensor systems, certified reference materials and instrumental analytical-chemical methods contribute to safety and functionality in hydrogen technologies.
This article gives a brief overview of SensRef activities in the Competence Centre H2Safety@BAM on the issues: Analytical methods for the determination of hydrogen purity, certified reference materials as measurement standards with regard to gas quality (primary calibrators) of BAM, test methods for gas sensor systems to detect hydrogen in air as well as the application of fibre-optic sensor systems to monitor the expansion and ageing behaviour of composite containers in hydrogen technologies.
Der Vortrag zum Mess- und Prüfverfahren mit verschiedenen Sensortechnologien und Ultraschallwellen beinhaltet die Themen:
Metrologie zur Wasserstoffspeicherung - Euramet-Vorhaben "MefHySto",
Erkennung von freigesetztem Wasserstoff sowie die Bestimmung des Wasserstoff-Luftverhälntisses mit Gassensoren, zerstörungsfreie Fehlstellenerkennung mit integriertem Zustandsüberwachungssystem basierend auf geführten Ultraschallwellen zur Lebensdauerüberwachung von Composite-Behältern (Wasserstoffspeicher) sowie faseroptische Sensorik zur Schadenfrüherkennung von Wasserstoffspeichern aufgrund erkennbarer Dehnungsänderungen an Druckbehältern.
Imaging in the shortwave-infrared region (SWIR, λ = 1000–2500 nm) has the potential to enable deep tissue imaging with high resolution. Critical to the development of these Methods is the identification of low molecular weight, biologically compatible fluorescent probes that emit beyond 1000 nm.
Exchanging the bridging oxygen atom on the xanthene scaffold (C10’ position) with electron withdrawing groups has been shown to lead to significant redshifts in absorbance and emission. Guided by quantum chemistry computational modeling studies, we investigated the installation of a Ketone bridge at the C10’ position. This simple modification extends the absorbance maxima to 860 nm and the emission beyond 1000 nm, albeit with reduced photon output. Overall, These studies demonstrate that broadly applied xanthene dyes can be extended into the SWIR range.
Portable, antikörperbasierte Analysenverfahren für die Schadstofferfassung im Wasserkreislauf
(2021)
Die Wasseranalytik wird bestimmt von zwei Hauptbedarfen, einerseits der Erfassung der Gewässergüte und Grundwassergüte als Basis für die Bereitstellung einwandfrei-en Trinkwassers und zum anderen des Monitorings der Wasserqualität in den Prozes-sen der Wasseraufbereitung und der Abwasserreinigung. Für beide Anwendungsbe-reiche ist eine laborbasierte Analytik eher hinderlich, werden die Analysenergebnisse doch eigentlich vor Ort benötigt, um etwa Beprobungskampagnen rasch anpassen zu können. Desweiteren werden die Daten auch schnell benötigt, um zeitnah in die technischen Prozesse einzugreifen. Organische Kontaminanten werden meist über chromatographische Verfahren, häufig gekoppelt mit einer massenspektrometrischen Detektion, in instrumentelle Labormethoden erfasst und die hochauflösende Massen-spektrometrie und die Non-target-Analytik haben viel zum Wissen über das Vorkom-men, insbesondere von sog. „emerging contaminants“, beigetragen, sowie zum Ver-ständnis der beteiligten Eintragspfade und Abbauwege. Moderne, portable Analy-senmethoden und insbesondere Sensoren werden zukünftig aber ihren Platz in der Schadstofferfassung im Wasserkreislauf einnehmen. Dies gilt insbesondere für anti-körperbasierte Analysenverfahren, da erst diese oft die nötige Selektivität und Sensitivität in die Detektionsmethoden einbringen.
A vast number of emerging pollutants has been detected in the environment over the last decades. Analytical methods suitable for trace analysis are needed that are desirably also fast, inexpensive and, if possible, robust and portable. Immunoanalytical, i.e. antibody-based, methods which are available in a broad range of formats, can be profitably used here to analyse for the distribution and the trends of concentration levels of contaminants in the environment. Some of these formats are single-analyte but high-throughput methods. In order to use them wisely, indicator substances, sometimes called anthropogenic markers, should be selected and used in screening approaches. Other methods are suitable to be performed on portable instrumentation in the field (on-site) or in facilities such as wastewater treatment plants for on-line monitoring. Furthermore, there are array technologies that allow for parallel (multiplex) analysis of several analytes of interest.
The microtiter-plate based ELISA (Enzyme-linked Immunosorbent Assay) is the method of choice for the analysis of a large number of samples [1]. ELISAs are available to monitor for anthropogenic markers such as the antiepileptic carbamazepine, the analgesic diclofenac, the antihistaminic cetirizine, the steroid hormone estrone, the antimicrobial sulfamethoxazole, the stimulants caffeine and cocaine, the priority pollutant bisphenol A, and the bile acid isolithocholic acid. For on-site screening and monitoring, simpler formats, like mix-and-read assays, e.g. the Fluorescence Polarization Immunoassay (FPIA) [2] or Lateral-flow Immunoassays (LFIA) [3] are more suitable tools, the latter based on dipsticks or cassettes, that is why they are also called pregnancy test-like assays. The suitability of multi-analyte formats such as immunomicroarrays depends on the choice of a signal-producing system that provides small uncertainties and good reproducibility of the measurements. Bead-based (“suspension”) arrays read out in flow cytometers are a powerful platform for multiplex assays [4]. Electrochemical formats run on portable devices provide additional advantages as no light source is required. They are most promising for stand-alone analysers and biosensors
Portable, antikörperbasierte Analysenverfahren für die Schadstofferfassung im Wasserkreislauf
(2021)
Die Wasseranalytik wird bestimmt von zwei Hauptbedarfen, einerseits der Erfassung der Gewässergüte und Grundwassergüte als Basis für die Bereitstellung einwandfreien Trinkwassers und zum anderen des Monitorings der Wasserqualität in den Prozessen der Wasseraufbereitung und der Abwasserreinigung. Für beide Anwendungsbereiche ist eine laborbasierte Analytik eher hinderlich, werden die Analysenergebnisse doch eigentlich vor Ort benötigt, um etwa Beprobungskampagnen rasch anpassen zu können. Des Weiteren werden die Daten auch schnell benötigt, um zeitnah in die technischen Prozesse einzugreifen. Organische Kontaminanten werden meist über chromatographische Verfahren, häufig gekoppelt mit einer massenspektrometrischen Detektion, in instrumentellen Labormethoden erfasst, und die hochauflösende Massenspektrometrie und die Non-target-Analytik haben viel zum Wissen über das Vorkommen, insbesondere von sogenannten „Emerging Contaminants“, beigetragen, sowie zum Verständnis der beteiligten Eintragspfade und Abbauwege. Moderne, portable Analysenmethoden und insbesondere Sensoren werden zukünftig aber ihren Platz in der Schadstofferfassung im Wasserkreislauf einnehmen. Dies gilt insbesondere für antikörperbasierte Analysenverfahren, da erst diese oft die nötige Selektivität und Sensitivität in die Detektionsmethoden einbringen.
One of the most important chemicals used in the production of polymer plastics and coatings is bisphenol A. However, despite the large number of studies on the toxicity and hormonal activity of BPA, there are still open questions and thus considerable media attention regarding BPA toxicity. Hence, it is necessary to develop a sensitive, simple, cost-efficient, specific, portable, and rapid method for monitoring bisphenol A and for high sample throughput and on-site screening analysis. Lateral flow immunoassays have potential as rapid tests for on-site screening. To meet sensitivity criteria, they must be carefully optimized. A latex microparticle-based LFIA for detection of BPA was developed. The sensitivity of the assay was improved by non-contact printing of spot grids as the control and test lines with careful parameter optimization. Results of the test could be visually evaluated within 10 min with a visual cut-off of 10 µg/L (vLOD). Alternatively, photographs were taken, and image analysis performed to set up a calibration, which allowed for a calculated limit of detection (cLOD) of 0.14 µg/L. The method was validated for thermal paper samples against ELISA and LC–MS/MS as reference methods, showing good agreement with both methods