Sanitär- und Kommunaltechnik; Umwelttechnik
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Paper des Monats
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Flow cytometry-based immunoassays are valuable in biomedical research and clinical applications due to their high throughput and multianalyte capability, but their adoption in areas such as food safety and environmental monitoring is limited by long assay times and complex workflows. Rapid, simplified bead-based cytometric immunoassays are needed to make these methods viable for point-of-need applications, especially with the increasing accessibility of miniaturized cytometers. This work introduces superparamagnetic hybrid polystyrene-silica core−shell microparticles as promising alternatives to conventional polymer beads in competitive cytometric immunoassays. These beads, featuring high specificity, sensitivity, and excellent handling capabilities via magnetic separation, were evaluated with three different antibodies and binding methods, showing variations in signal intensity based on the antibody and its attachment method. The optimal performance was achieved through a secondary antibody binding approach, providing strong and consistent signals with minimal uncertainty. The optimized protocol made it possible to achieve a detection limit of 0.025 nM in a total assay time of only 15 min and was successfully used to detect ochratoxin A (OTA) in raw flour samples. This work highlights the potential of these beads as versatile tools for flow cytometry-based immunoassays, with significant implications for food safety, animal health,
environmental monitoring, and clinical diagnostics.
ABSTRACT: Microorganisms often live in habitats characterized by fluid flow, and their adhesion to surfaces in industrial systems or clinical settings may lead to pipe clogging, microbially influenced corrosion, material deterioration, food spoilage, infections, and human illness. Here, a novel microfluidic platform was developed to investigate biofilm formation under precisely controlled (i) cell concentration, (ii) temperature, and (iii) flow conditions. The developed platform central unit is a single-channel microfluidic flow cell designed to ensure ultrahomogeneous flow and condition in its central area, where features, e.g., with trapping properties, can be incorporated. In comparison to static and macroflow chamber assays for biofilm studies, microfluidic chips allow in situ monitoring of biofilm formation under various flow regimes and have better environment control and smaller sample requirements.
Flow simulations and experiments with fluorescent particles were used to simulate bacteria flow in the platform cell for calculating flow velocity and direction at the microscale level. The combination of flow analysis and fluorescent strain injection in the cell showed that microtraps placed at the center of the channel were efficient in capturing bacteria at determined positions and to study how flow conditions, especially microvortices, can affect biofilm formation. The microfluidic platform exhibited improved performances in terms of homogeneity and robustness for in vitro biofilm formation. We anticipate the presented platform to be suitable for broad, versatile, and high-throughput biofilm studies at the microscale level.
Understanding interfacial chemistry: probing surface modifications by differential phage display
(2024)
Phage surface display combined with next-generation sequencing allows for the in-depth analysis of millions of sequences and enables the discovery of specific target binding peptides. The vast amount of valuable data from next-generation phage display experiments on material surfaces can be used to gain insight into peptide-based molecular interactions to reveal the local interfacial chemistry. The talk will discuss a developed differential strategy for data-driven probing of 3D printed electrodes before and after electrochemical activation.
In clinical magnetic resonance imaging, non-specific Gd-based contrast agents (GBCAs) are frequently used to improve image quality. However, the interaction of GBCAs with tissue components is not yet fully understood. Many diseases, including inflammation, fibrosis, and tumor invasion, are associated with characteristic changes of the extracellular matrix (ECM). The ECM is a three-dimensional scaffold that embeds the cells of all mammalian tissues. It is composed of structural proteins (e.g., collagen, elastin) and proteoglycans, which consist of glycosaminoglycans (GAGs) covalently bound to a protein core. GAGs are characterized by their ability to form complexes with cations such as lanthanides. Thus, GAGs could be a potential binding partner for GBCAs as a whole or for dechelated Gd. Laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA/ICP-ToF-MS) was used to investigate the uptake and distribution of different GBCAs in spheroids mimicking biological tissue and exhibiting different ECM expressions. Spheroids from Chinese hamster ovary (CHO) cells and GAG-depleted CRL-2242 cells were incubated with gadolinium chloride and various linear and macrocyclic GBCAs. Although all spheroids were exposed to identical Gd concentrations, differences in the amount of Gd taken up were observed. Gadolinium chloride is more strongly absorbed and accumulates mainly in the outer regions of the spheroids. In contrast, after incubation with linear and macrocyclic GBCAs, Gd is detected in the interior of both types of spheroids. Furthermore, differences in the Gd amount were found depending on the GBCA used. However, further studies are needed to elucidate such complex interactions, also using other (bio)analytical techniques.
Microplastic determination in food and surface waters will be increasingly carried out in the course of future directives and regulations, such as EU drinking water directive and wastewater directive. In addition to unique identification, this also includes reliable quantification. Two different methodological approaches are used for the quantification. With vibrational spectroscopic techniques such as µ-FTIR and µ-Raman, results are obtained in the form of particle number, size and shape. Instead, with thermal analytical technics as TED-GC/MS and Py-GC-MS the results are expressed as mass concentration.. Both concepts offer different information variables. In terms of routine monitoring, it is necessary to obtain a rapid sequence from sampling to the detection result. For this reason, this study focuses on TED-GC/MS and Py-GC-MS. Even though thermal analytical methods generally require less sample preparation, some matrices require it. This is usually done if the analyte concentration is too low or if strong matrix effects such as signal suppression and false positive signals occur.
This talk presents advanced sample preparation for baby milk powder as food example and density separation for microplastic analysis in surface waters.
A preparation protocol based on citric acid was selected for the milk to remove as much as possible of the matrix. The low pH value leads to a fast and effective protein precipitation and minimizes filter cake formation, making filtration possible, reduces the number and the amount of compounds in detection and hence, simplifies the evaluation.
Microplastics in surface waters and sediments must be concentrated not only because of their low microplastics mass content but also in terms of homogeneity. For this purpose, a density separation was carried out using a concentrated sodium iodide solution, which led to a high reduction of the inorganic mineral matrix and made possible to obtain a representative subsample of initial masses of up to 80 g.
Die Gruppe der PFAS (Per- und polyfluorierte Alkylsubstanzen) mit mehr als 10.000 Substanzen stellt ein zunehmendes Problem bei der Bewertung und Entsorgung belasteter Abfälle dar. Die zuverlässige PFAS-Analytik stellt hier aufgrund der Vielzahl an Einzelparametern mit zum Teil sehr großen Konzentrationsunterschieden eine komplexe Herausforderung dar.
Der Vortrag gibt zunächst einen Überblick über grundlegende Anforderungen an die LC-MS/MS Analytik von PFAS-Targetsubstanzen. Am Beispiel eines von BAM und SenMVKU organisierten Ringversuches 2024 zur Bestimmung von PFAS in Bodenproben (Feststoffe und Eluate) wird auf spezifische Fragestellungen zur PFAS-Analytik eingegangen.
Zur Verbesserung von Richtigkeit und Vergleichbarkeit ist die Einhaltung von Normvorgaben und die Anwendung von Qualitätssicherungsmaßnahmen unerlässlich. Hierzu gehören u.a. die Verwendung zuverlässiger Kalibrierstandards, die Kalibrierung mit definierten n-Isomeren, die Quantifizierung der Summe aus n-/br-Isomeren, der Einsatz isotopenmarkierter interner Standards für die LC-MS/MS Analyse, die Verwendung von Matrix-Referenzmaterialien sowie die Teilnahme an Ringversuchen.
In September 2023, the European Commission introduced a new regulation to
reduce microplastic (MP) emissions into the environment, including the sale and
use of intentionally added (large) MP < 5 mm (ISO/TR 21960: 2020). This explicitly
applies to the use of synthetic rubber granulate infill in artificial turf installations,
which are complex multi-component systems consisting of multiple synthetic
polymers (Fig. 1). In addition, abrasions of synthetic grass fibres and other turf
components are also considered as MP sources. Although this has a major impact
on public recreational sports, there is so far no sufficient data to estimate the MP
emissions from artificial turf sports pitches into the environment and thus their
relevance as a source of MP pollution.
To close this gap, this study compared environmental contaminant emissions of
three artificial turf scenarios at different ageing states (unaged, artificially and
real-time aged): the past (old turf: fossil based, synthetic infill), present (most
commonly installed in Germany: fossil based, EPDM infill) and future (turf with
recycled grass fibres, no synthetic infill). Accelerated ageing by UV weathering and
mechanical stress was carried out to simulate the outdoor weathering during the
lifespan of approx. 15 years. MP emissions and released environmentally relevant
contaminants posing a risk to the groundwater were simultaneously sampled using
the newly developed Microplastic Eluate Lysimeter manufactured at BAM (Fig. 2).
MP contents were analysed using smart microfilter crucibles (mesh size: 5 μm)
with subsequent MP detection by TED-GC/MS. Additionally, concentrations of
polycyclic aromatic hydrocarbons were determined using GC/MS and heavy metals
using ICP-AES.
Since they were first discovered, antibiotics have been used extensively to treat diseases caused by bacteria. This increasing and uncontrollable use is causing a number of environmental problems. Unfortunately, traces of various antibiotics can be found in drinking water also in wastewater.
In this study was focused on the detection of clarithromycin (CLA) in wastewater using the immunofluorescence ELISA assay which is a highly selective and sensitive technique. ELISA is a multi-type of technique and the one used in this study was the indirect competitive ELISA. For the detection of CLA, a checkerboard was performed to obtain a dilution factor until 1:1,000,000 for the antigen (CLA-BSA) with a concentration of 5 ng/mL and a dilution factor until 1:5,120,00 for the primary antibody (anti-CLA mAb) with a concentration of 1. 035 ng/mL. Standardization was performed to obtain a better profile of the 4-parameter curve A, B, C and D which determines the maximum, minimum and inflection concentration. In addition, a pure synthetic water experiment was used to determine the stability of the assay and the matrix effect due to some interactions from chemicals or components used during the assays.
The detection of CLA in pure water in Germany showed that the concentration of CLA differs from province to province and differs from time of year, however, the commonly detected concentration of CLA in pure water was ng/L.
AbstractA prerequisite for the recycling of mineral wool is information about the type of material, that is, whether it is glass wool or rock wool. As mineral wool produced before the year 2000 can be potentially carcinogenic, it is furthermore important to distinguish between “old” and “new” wool when handling the material. Based on VDI 3492, it is possible to determine the material and, in the case of rock wool, the age by analyzing the mass fractions of eight oxides, which are the main components of mineral wool. This study presents the X‐ray fluorescence (XRF) analyses of 141 man‐made mineral fibers collected in Germany. Only in a few cases it was not possible to clearly assign the material type. In contrast, the identification of “old” and “new” rock wool posed a challenge as there were many borderline samples. Based on the available data, a chemometric model was developed that can classify “old” and “new” RW with a sensitivity of 93% and 89% and with a specificity of 100% in both cases. However, care must be taken when oxide contents are close to the specification limits. The reason for this mainly lies in the overlapping intervals of key oxides as suggested by VDI 3492, and, to a lesser extent, in the uncertainties typically occurring in the XRF‐based analysis of oxides. With this study, a comprehensive collection and evaluation of XRF data on mineral wool is made available, which can serve as a reference database for future users.
Clay is increasingly coming back into people's consciousness with the demand for ecological, healthy and sustainable building materials.
Earthen building materials, including clay from the historical building stock, offer a high potential for their reusability and thus for saving natural resources. Unfired clay can be reused at any time and indefinitely. Dry clay only needs to be crushed and moistened with water and it can be processed again. However, there exist only a few studies on the contamination with pollutants and on the accumulation of salts in existing historic buildings regarding the evaluation of reuse potential. Within the framework of a project, preliminary tests are being carried out taking into account the previous usage of the buildings. In order to evaluate the suitability for indoor use, the potential transfer of volatile organic compounds into the air is investigated.
Fine fractions of C&D waste (particle size less than 2 mm) are currently mostly landfilled. However, such materials can be suitable for substituting primary resources of earthen building materials provided they are adequately processed. Therefore, in another research project it is investigated whether and to what extent fine and ultra-fine fractions of construction and demolition waste processed by washing can be employed for that purpose. The recycled fines are investigated considering organic and inorganic contaminants in solid matter and leaching tests are carried out to assess the potential to mobilize harmful substances. Additionally, the recycled fines are investigated in emission test chambers regarding indoor air requirements to construction products. The results will be transferred to standardization work as in Germany in standards for earthen building materials only aggregates and binders from natural sources are permitted currently.