TY - JOUR A1 - Kimani, Martha Wamaitha A1 - Kislenko, Evgeniia A1 - Gawlitza, Kornelia A1 - Rurack, Knut T1 - Fluorescent molecularly imprinted polymer particles for glyphosate detection using phase transfer agents JF - Scientific reports N2 - In this work, molecular imprinting was combined with direct fluorescence detection of the pesticide Glyphosate (GPS). Firstly, the solubility of highly polar GPS in organic solvents was improved by using lipophilic tetrabutylammonium (TBA+) and tetrahexylammonium (THA+) counterions. Secondly, 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 fluorescent molecularly imprinted polymer (MIP) shells on the surface of sub-micron silica particles using chloroform as porogen. 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+ in a biphasic assay, enabling the direct fluorescence detection and quantification of GPS in water. A limit of detection of 1.45 μM and a linear range of 5–55 μM were obtained, which match well with WHO guidelines for the acceptable daily intake of GPS in water (5.32 μM). KW - Glyphosate KW - Molecular imprinting KW - Core-shell particles KW - Fluorescent sensors PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-555281 DO - https://doi.org/10.1038/s41598-022-16825-9 SN - 2045-2322 VL - 12 IS - 1 SP - 1 EP - 15 PB - Macmillan Publishers Limited CY - London AN - OPUS4-55528 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - You, Zengchao A1 - Akkus, Asli A1 - Weisheit, W. A1 - Giray, Thorsten A1 - Penk, Sibylle A1 - Buttler, Sabine A1 - Recknagel, Sebastian A1 - Abad Andrade, Carlos Enrique T1 - Multielement analysis in soils using nitrogen microwave inductively coupled atmospheric pressure plasma mass spectrometry JF - Journal of analytical atomic spectrometry N2 - In this study, we employed nitrogen microwave inductively coupled atmospheric-pressure plasma (MICAP) combined with quadrupole mass spectrometry (MS) and a liquid sample introduction system to analyze heavy metals in soils. The vanadium, cobalt, nickel, zinc, copper, chromium, arsenic, lead, and cadmium contents in seven reference and three environmental soil samples determined using MICAP-MS were within the uncertainty of the reference values, indicating that MICAP-MS is promising for soil analysis similar to the conventional inductively coupled plasma mass spectrometry (ICP-MS) technique. In addition, the limits of detection (LODs) and sensitivity of both techniques using N2 and Ar plasma were of the same order of magnitude. Furthermore, the performance of MICAP-MS under different N2 purity was investigated, and we found that the plasma formation and ionization efficiency were not influenced by the impurities in the gas. A prominent advantage of MICAP-MS is the low operating cost associated with gas consumption. In this work, MICAP-MS used nitrogen, which is cheaper than argon, and consumed 25% less gas than ICP-MS. Using low-purity N2 can further reduce the gas cost, making MICAP-MS more cost effective than ICP-MS. These results suggest that MICAP-MS is a promising alternative to ICP-MS for the analysis of heavy metals in the soil. KW - Soil KW - Microwave inductively coupled atmospheric pressure mass spectrometry (MICAP-MS) KW - Nitrogen plasma KW - Multi-element analysis PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-561048 DO - https://doi.org/10.1039/d2ja00244b SN - 0267-9477 VL - 37 IS - 12 SP - 2556 EP - 2562 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-56104 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Oliveira Guilherme Buzanich, Ana A1 - Cakir, Cafer Tufan A1 - Radtke, Martin A1 - Haider, M. Bilal A1 - Emmerling, Franziska A1 - F. M. Oliveira, P. A1 - Michalchuk, Adam A. L. T1 - Dispersive x-ray absorption spectroscopy for time-resolved in situ monitoring of mechanochemical reactions JF - Journal of chemical physics N2 - X-ray absorption spectroscopy (XAS) provides a unique, atom-specific tool to probe the electronic structure of solids. By surmounting long-held limitations of powder-based XAS using a dynamically averaged powder in a Resonant Acoustic Mixer (RAM), we demonstrate how time-resolved in situ (TRIS) XAS provides unprecedented detail of mechanochemical synthesis. The use of a custom-designed dispersive XAS (DXAS) setup allows us to increase the time resolution over existing fluorescence measurements from ∼15 min to 2 s for a complete absorption spectrum. Hence, we here establish TRIS-XAS as a viable method for studying mechanochemical reactions and sampling reaction kinetics. The generality of our approach is demonstrated through RAM-induced (i) bottom-up Au nanoparticle mechanosynthesis and (ii) the synthesis of a prototypical metal organic framework, ZIF-8. Moreover, we demonstrate that our approach also works with the addition of a stainless steel milling ball, opening the door to using TRIS-DXAS for following conventional ball milling reactions. We expect that our TRIS-DXAS approach will become an essential part of the mechanochemical tool box. KW - In situ studies KW - Dipsersive XAS KW - Mechanochemistry KW - Time-resolved PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567659 DO - https://doi.org/10.1063/5.0130673 SN - 1089-7690 VL - 157 IS - 21 SP - 1 EP - 12 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-56765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burnage, Samual A1 - Bell, Jérémy A1 - Wan, Wei A1 - Kislenko, Evgeniia A1 - Rurack, Knut T1 - Combining a hybrid chip and tube microfluidic system with fluorescent molecularly imprinted polymer (MIP) core–shell particles for the derivatisation, extraction, and detection of peptides with N-terminating phosphorylated tyrosine JF - Lab on a Chip N2 - The reliable identification and quantitation of phosphorylated amino acids, peptides and proteins is one of the key challenges in contemporary bioanalytical research, an area of particular interest when attempting to diagnose and treat diseases at an early stage. We have developed a synthetic probe for targeting phosphorylated amino acids, based on core–shell submicron-sized particles consisting of a silica core, coated with a molecularly imprinted polymer (MIP) shell. The MIP layer contains a fluorescent probe crosslinker which binds selectively to phosphorylated tyrosine (pY) moieties with a significant imprinting factor (IF) and responds with a "light-up” fluorescence signal. The bead-based ratiometric detection scheme has been successfully transferred to a microfluidic chip format and its applicability to rapid assays has been exemplarily shown by discriminating a pY-terminating oligopeptide against its nonphosphorylated counterpart. Such miniaturised devices could lead to an automated pY or pY N-terminated peptide measurement system in the future. The setup combines a modular microfluidic system for amino acid derivatisation, extraction (by micropillar co-flow) and selective adsorption and detection with the fluorescent MIP core–shell particle probes. A miniaturised optical assembly for low-light fluorescence measurements was also developed, based on miniaturised opto-electronic parts and optical fibres. The emission from the MIP particles upon binding of pY or pY N-terminated peptides could be monitored in real-time. KW - Microfluidics KW - Molecularly imprinted polymers KW - Phosphorylated peptides KW - Fluorescence KW - Core-shell particles PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569204 DO - https://doi.org/10.1039/d2lc00955b SN - 1473-0197 VL - 23 IS - 3 SP - 466 EP - 474 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-56920 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nordholt, Niclas A1 - O'Hara, Kate A1 - Resch-Genger, Ute A1 - Blaskovich, M. A1 - Rühle, Bastian A1 - Schreiber, Frank T1 - A fluorescently labelled quaternary ammonium compound (NBD-DDA) to study resistance mechanisms in bacteria JF - Frontiers in microbiology N2 - Quaternary ammonium compounds (QACs) are widely used as active agents in disinfectants, antiseptics, and preservatives. Despite being in use since the 1940s, there remain multiple open questions regarding their detailed mode-of-action and the mechanisms, including phenotypic heterogeneity, that can make bacteria less susceptible to QACs. To facilitate studies on resistance mechanisms towards QACs, we synthesized a fluorescent quaternary ammonium compound, namely N-dodecyl-N,N-dimethyl-[2-[(4-nitro-2,1,3-benzoxadiazol-7-yl)amino]ethyl]azanium-iodide (NBD-DDA). NBD-DDA is readily detected by flow cytometry and fluorescence microscopy with standard GFP/FITC-settings, making it suitable for molecular and single-cell studies. As a proof-of-concept, NBD-DDA was then used to investigate resistance mechanisms which can be heterogeneous among individual bacterial cells. Our results reveal that the antimicrobial activity of NBD-DDA against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa is comparable to that of benzalkonium chloride (BAC), a widely used QAC, and benzyl-dimethyl-dodecylammonium chloride (BAC12), a mono-constituent BAC with alkyl-chain length of 12 and high structural similarity to NBD-DDA. Characteristic time-kill kinetics and increased tolerance of a BAC tolerant E. coli strain against NBD-DDA suggest that the mode of action of NBD-DDA is similar to that of BAC. As revealed by confocal laser scanning microscopy (CLSM), NBD-DDA is preferentially localized to the cell envelope of E. coli, which is a primary target of BAC and other QACs. Leveraging these findings and NBD-DDA‘s fluorescent properties, we show that reduced cellular accumulation is responsible for the evolved BAC tolerance in the BAC tolerant E. coli strain and that NBD-DDA is subject to efflux mediated by TolC. Overall, NBD-DDA’s antimicrobial activity, its fluorescent properties, and its ease of detection render it a powerful tool to study resistance mechanisms of QACs in bacteria and highlight its potential to gain detailed insights into its mode-of-action. KW - Antimicrobial resistance KW - Bacteria KW - Disinfection KW - Biocides PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563811 DO - https://doi.org/10.3389/fmicb.2022.1023326 SN - 1664-302X IS - 13 SP - 1 EP - 13 PB - Frontiers Media CY - Lausanne AN - OPUS4-56381 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -