Datei im Netzwerk der BAM verfügbar ("Closed Access")
Filtern
Dokumenttyp
- Zeitschriftenartikel (12)
- Posterpräsentation (10)
- Beitrag zu einem Tagungsband (4)
- Vortrag (4)
- Buchkapitel (1)
- Forschungsbericht (1)
Sprache
- Englisch (30)
- Deutsch (1)
- Mehrsprachig (1)
Schlagworte
- Fluorescence (12)
- Air quality (3)
- Air quality monitoring (3)
- Ammonia gas sensor (3)
- Core-shell particles (3)
- Environment (3)
- Mesoporous silica materials (3)
- Spectroscopy (3)
- Standard gas generator (3)
- Ammonia (2)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (4)
Per- and polyfluoroalkyl substances (PFAS) are a class of man-made organo-fluorine chemicals that have become environmental contaminants of emerging concern, originating from a variety of materials such as adhesive, stain- and oil-resistant coatings, firefighting foams, etc. The high strength of this C-F bond makes PFAS thermodynamically stable and resistant to (bio)degradation, thus retaining them in the environment over time. Perfluoroalkyl carboxylic acids (PFCAs), one category of the most used PFAS, consist of a fully fluorinated carbon backbone and a charged carboxylic acid headgroup, and have been classified as Substances of Very High Concern (SVHC) and added to the REACH Candidate List due to their persistence in the environment, non-biodegradability and toxicological effects.[1-2] Traditional techniques for the analysis of PFCAs include GC-MS, HRMS and HPLC-based approaches, which are laborious, not portable, costly and require trained personnel. In contrast, fluorescence assays can be designed as easy-to-operate, portable and cost-effective methods with high sensitivity and fast response. Integration of fluorescent probes with an adequately miniaturized assay enables a promising alternative for PFCAs analysis.
Here, a novel guanidine fluorescent probe has been synthesized and fully characterized for the detection of PFCAs in a biphasic extract-&-detect assay. The fluorescent probe was then incorporated into polymeric matrices supported by a red dye-doped SiO2 nanoparticle to construct a dual-emission sensing platform. Such a system allows precise and selective detection of PFCAs, reducing the interference of competitors, matrix effects and other factors except for the PFCAs. The system was then employed in a droplet-based microfluidic setup which offers a portable and easy to operate detection platform.
Glyphosate (GPS) is the most widely used pesticide in the world whose use increased dramatically after the introduction of genetically modified crops engineered to resist its herbicidal action during application. In recent years, there have been growing concerns over its toxicity following its classification by the International Agency for Research on Cancer (IARC) as a probable carcinogen as well as reports of its ecotoxicological effects. This resulted in increased efforts to develop quick and sensitive detection methods.
In this work, molecular imprinting was combined with direct fluorescence detection of GPS by improving its solubility in organic solvents using tetrabutylammonium (TBA+) and tetrahexylammonium (THA+) as counterions. To achieve fluorescence detection, a fluorescent crosslinker containing urea binding motifs was used as a probe for GPS-TBA and GPS-THA salts in chloroform, generating stable complexes through hydrogen bond formation. The GPS/fluorescent dye complexes were imprinted into 2–3 nm molecularly imprinted polymer (MIP) shells on the surface of sub-micron silica particles. Thus, the MIP binding behavior could be easily evaluated by fluorescence titrations in suspension to monitor the spectral changes upon addition of the GPS analytes. While MIPs prepared with GPS-TBA and GPS-THA both displayed satisfactory imprinting following titration with the corresponding analytes in chloroform, GPS-THA MIPs displayed better selectivity against competing molecules. Moreover, the THA+ counterion was found to be a more powerful phase transfer agent than TBA+, enabling the direct fluorescence detection and quantification of GPS in water in a biphasic assay. A limit of detection of 1.45 µM and a linear range of 5–55 µM, which matches well with WHO guidelines for the acceptable daily intake of GPS in water (5.32 µM), have been obtained. The assay can be further optimized to allow miniaturization into microfluidic devices and shows potential for on-field applications by untrained personnel.
In the present paper the development of a semi-automated device for long-term monitoring of gaseous ammonia is described. A sensor material was produced that changes its optical properties in the pres-ence of low concentrations of ammonia in air. The implementation into an electronic device enables precise, simple, economic and fast monitoring of low concentrations of harmful gases, like ammonia, and hence can help to improve the climate monitoring in livestock housing, barns or stables.
In the present paper the development of a semi-automated device for long-term monitoring of gaseous ammonia is described. A sensor material was produced that changes its optical properties in the pres-ence of low concentrations of ammonia in air. The implementation into an electronic device enables precise, simple, economic and fast monitoring of low concentrations of harmful gases, like ammonia, and hence can help to improve the climate monitoring in livestock housing, barns or stables.
Dual-fluorescent molecularly imprinted nanoparticles with a red-emissive carbon nanodot-doped silica core and a chlorogenic acid-imprinted fluorescent polymer layer are prepared and their use in ratiometric fluorometric analysis is described. Nanoparticle probes consisting of a shielded and stably emitting core and a shell with embedded binding sites that indicates the presence of an analyte with a change in emission allow for internally referenced measurements potentially accounting for detrimental influences from instrument drifts, light source fluctuations or sensor materials-related inhomogeneities.
Glycoproteins are abundant on the cell surface of mammals, providing structural support, modulating cell Membrane properties, and acting as signaling agents. Variation of glycosylation patterns has been found to indicate various disease states, including cell malignancy. Sialic acid (SA) is present as a terminating group on cell-surface glycans, and its overexpression has been linked to several types of cancer. Detection of SA on the cell surface is therefore critical for detection of cancer in its early stages. In this work, a fluorescent molecularly imprinted polymer layer targeting SA was synthesized on the surface of silica-coated polystyrene (PS) particles. Compared to previous works, a PS core supplies a lighter, lower-density support for improved suspension stability and scattering properties. Moreover, their smaller size provides a higher surface-area-to-volume ratio for binding. The incorporation of a fluorescent monomer in the MIP shell allowed for simple and rapid determination of binding specificity in polar media due to a deprotonation−reprotonation interaction mechanism between the fluorescent monomer and SA, which led to spectral changes.
Upon titration of the MIP particles with SA in suspension, an increase in fluorescence emission of the particles was observed, with the MIP particles binding SA more selectively compared to the nonimprinted polymer (NIP) control particles. In cell staining experiments performed by flow cytometry, the binding behavior of the MIP particles compared favorably with that of SA-binding lectins. NIPs prepared with a “dummy” template served as a better negative control in cell binding assays due to the favorable inward orientation of template-binding functional groups in the polymer shell, which reduced nonspecific binding. The results show that fluorescent MIPs targeting SA are a promising tool for in vitro fluorescence staining of cancerous cells and for future diagnosis of cancer at early stages.
The present paper describes the development of a sensor material that changes its fluorescence in the presence of gaseous ammonia in a relevant concentration range. The implementation into a semi-automatic gas measurement device enables low-cost, precise, simple and fast monitoring of low con-centrations of harmful gases, like ammonia, and hence can help to improve the climate monitoring in livestock housing, barns or stables.
Functional core/shell particles are highly sought after in analytical chemistry, especially in methods suitable for single-particle analysis such as flow cytometry because they allow for facile multiplexed detection of several analytes in a single run. Aiming to develop a powerful bead platform of which the core particle can be doped in a straightforward manner while the shell offers the highest possible sensitivity when functionalized with (bio)chemical binders, polystyrene particles were coated with different kinds of mesoporous silica shells in a convergent growth approach. Mesoporous shells allow us to obtain distinctly higher surface areas in comparison with conventional nonporous shells. While assessing the potential of narrow- as well as wide-pore silicas such as Mobil composition of matter no. 41 (MCM-41) and Santa Barbara amorphous material no. 15 (SBA-15), especially the synthesis of the latter shells that are much more suitable for biomolecule anchoring was optimized by altering the pH and both, the amount and type of the mediator salt. Our studies showed that the best performing material resulted from a synthesis using neutral conditions and MgSO4 as an ionic mediator. The analytical potential of the particles was investigated in flow cytometric DNA assays after their respective functionalization for individual and multiplexed detection of short oligonucleotide strands. These experiments revealed that a two-step modification of the silica surface with amino silane and succinic anhydride prior to coupling of an amino-terminated capture DNA (c-DNA) strand is superior to coupling carboxylic acid-terminated c-DNA to aminated core/shell particles, yielding limits of detection (LOD) down to 5 pM for a hybridization assay, using labeled complementary single-stranded target DNA (t-DNA) 15mers. The potential of the use of the particles in multiplexed analysis was shown with the aid of dye-doped core particles carrying a respective SBA-15 shell. Characteristic genomic sequences of human papillomaviruses (HPV) were chosen as the t-DNA analytes here, since their high relevance as carcinogens and the high number of different pathogens is a relevant model case. The title particles showed a promising performance and allowed us to unequivocally detect the different high- and low-risk HPV types in a single experimental run.
This paper describes the development of a semi-automatic gas measurement device presenting potentially a broad range of applications, noteworthy in the agricultural sector. Non-reversible fluorescent molecular sensors were designed and syn-thesized. Upon, integration into a hydrogel matrix with an optimal ratio of co-solvents, the sensors reacting selectively to ammonia were illuminated by excitation light to produce a concentration-correlated fluorescence emission. An automated mechanical-elec-trical device initiates a given gas mixture and thus simulates con-centrations similar to a threshold value. The aim of this project is to develop a sensor or a low-cost method which can monitor low concentrations of harmful gases and aid in their elimination or regulation in livestock housing, barns or stables.
Digital holographic cytometry (DHC) is a state-of-the-art quantitative Phase imaging (QPI) method that permits time-lapse imaging of cells without induced cellular toxicity. DHC platforms equipped with semi-automated image segmentation and analysis software packages for assessing cell behavior are commercially available. In this study we investigate the possible uptake of nanoprobes in macrophages in vitro over time.