TY - JOUR A1 - Valderrey, Virginia A1 - Gawlitza, Kornelia A1 - Rurack, Knut T1 - Thiourea- and Amino-Substituted Benzoxadiazole Dyes with Large Stokes Shifts as Red-Emitting Probe Monomers for Imprinted Polymer Layers Targeting Carboxylate-Containing Antibiotics N2 - Bifunctional fluorescent molecular oxoanion probes based on the benzoxadiazole (BD) chromophore are described which integrate a thiourea binding motif and a polymerizable 2-aminoethyl methacrylate unit in the 4,7-positions of the BD core. Concerted charge transfer in this electron donor-acceptor-donor architecture endows the dyes with strongly Stokes shifted (up to >250 nm) absorption and fluorescence. Binding of electron-rich carboxylate guests at the thiourea receptor leads to further analyte-induced red-shifts of the emission, shifting the fluorescence maximum of the complexes to ≥700 nm. Association constants for acetate are ranging from 1–5×105 M−1 in acetonitrile. Integration of one of the fluorescent probes through its polymerizable moiety into molecularly imprinted polymers (MIPs) grafted from the surface of submicron silica cores yielded fluorescent MIP-coated particle probes for the selective detection of antibiotics containing aliphatic carboxylate groups such as enoxacin (ENOX) at micromolar concentrations in highly polar solvents like acetonitrile. KW - Molecular imprinting KW - Anion recognition KW - Antibiotics KW - Benzoxadiazole dyes KW - Charge transfer KW - Fluorescence PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545027 DO - https://doi.org/10.1002/chem.202104525 SN - 1521-3765 SP - 1 EP - 9 PB - Wiley-VCH AN - OPUS4-54502 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 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 - Kimani, Martha Wamaitha A1 - Beyer, S. A1 - El-Schich, Z. A1 - Gawlitza, Kornelia A1 - Rurack, Knut A1 - Gjörloff-Wingren, A. T1 - Imprinted Particles for Direct Fluorescence Detection of Sialic Acid in Polar Media and on Cancer Cells with Enhanced Control of Nonspecific Binding N2 - 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. KW - Flow cytometry KW - Sialic acid KW - Fluorescence KW - Molecularly imprinted polymers KW - Cancer cells PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525216 DO - https://doi.org/10.1021/acsapm.0c01353 VL - 3 IS - 5 SP - 2363 EP - 2373 PB - American Chemical Society AN - OPUS4-52521 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, Q. A1 - Shinde, S. A1 - Grasso, G. A1 - Caroli, A. A1 - Abouhany, R. A1 - Lanzillotta, M. A1 - Pan, G. A1 - Wan, Wei A1 - Rurack, Knut A1 - Sellergren, B. T1 - Selective detection of phospholipids using molecularly imprinted fluorescent sensory core-shell particles N2 - Sphingosine-1-phosphate (S1P) is a bioactive sphingo-lipid with a broad range of activities coupled to its role in G-protein coupled receptor signalling. Monitoring of both intra and extra cellular levels of this lipid is challenging due to its low abundance and lack of robust affinity assays or sensors. We here report on fluorescent sensory core-shell molecularly imprinted polymer (MIP) particles responsive to near physiologically relevant levels of S1P and the S1P receptor modulator fingolimod phosphate (FP) in spiked human serum samples. Imprinting was achieved using the tetrabutylammonium (TBA) salt of FP or phosphatidic acid (DPPA·Na) as templates in combination with a polymerizable nitrobenzoxadiazole (NBD)-urea monomer with the dual role of capturing the phospho-anion and signalling its presence. The monomers were grafted from ca 300 nm RAFT-modified silica core particles using ethyleneglycol dimethacrylate (EGDMA) as crosslinker resulting in 10–20 nm thick shells displaying selective fluorescence response to the targeted lipids S1P and DPPA in aqueous buffered media. Potential use of the sensory particles for monitoring S1P in serum was demonstrated on spiked serum samples, proving a linear range of 18–60 μM and a detection limit of 5.6 μM, a value in the same range as the plasma concentration of the biomarker. KW - Molecularly imprinted polymers KW - Phospholipids KW - Fluorescence KW - Dye monomers PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509485 DO - https://doi.org/10.1038/s41598-020-66802-3 SN - 2045-2322 VL - 10 IS - 1 SP - 9924 PB - Nature Research CY - London AN - OPUS4-50948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, Yijuan A1 - Gawlitza, Kornelia A1 - Valderrey, Virginia A1 - Bhattacharya, Biswajit A1 - Rurack, Knut T1 - Ratiometric Molecularly Imprinted Particle Probes for Reliable Fluorescence Signaling of Carboxylate-Containing Molecules N2 - In addition to sensitivity, selectivity, and portability, chemical sensing systems must generate reliable signals and offer modular configurability to address various small molecule targets, particularly in environmental applications. We present a versatile, modular strategy utilizing ratiometric molecularly imprinted particle probes based on BODIPY indicators and dyes for recognition and internal referencing. Our approach employs polystyrene core particles doped with a red fluorescent BODIPY as an internal standard, providing built-in reference for environmental influences. A molecularly imprinted polymer (MIP) recognition shell, incorporating a green-fluorescent BODIPY indicator monomer with a thiourea binding site for carboxylate containing analytes, is grafted from the core particles in the presence of the analyte as the template. The dual-fluorescent MIP probe detects fexofenadine as the model analyte with a change in green emission signal referenced against a stable red signal, achieving a detection limit of 0.13 μM and a broad dynamic range from 0.16 μM to 1.2 mM, with good discrimination against other antibiotics in acetonitrile. By selecting a versatile dye scaffold and recognition element, this approach can be extended to other carboxylate-containing analytes and/or wavelength combinations, potentially serving as a robust multiplexing platform. KW - Core-shell particles KW - Molecular imprinting KW - Pharmaceutical contaminants KW - Self-referenced measurements KW - Fluorescence PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-609385 DO - https://doi.org/10.1021/acsami.4c09990 SP - 1 EP - 13 PB - American Chemical Society (ACS) AN - OPUS4-60938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mansurova, Maria A1 - Johann, Sergej A1 - Kohlhoff, Harald A1 - Rurack, Knut A1 - Bartholmai, Matthias A1 - Bell, Jérémy T1 - On-Site Analytical Tool Based on Crude Oil Fluorescence and Chemometrics for the Rapid Determination of the Nature and Essential Properties of Oil Spills N2 - With the reduction of large oil spills because of stricter regulations and safety measures, the question of how to manage smaller oil spills arises. Few on-site analytical tools are available for first responders or other law enforcement personnel to rapidly test for crude oil in the early management of localized polluted areas. The approach reported here relies on well-described computer-assisted multivariate data analysis of the intrinsic fluorescence fingerprints of crude oils to build a multivariate model for the rapid classification of crude oils and the prediction of their properties. Thanks to a dedicated robust portable reader, the method allowed classification and accurate prediction of various properties of crude oil samples like density (according to API, the American Petroleum Institute and viscosity as well as composition parameters such as volume fractions of paraffins or aromatics. In this way, autonomous operation in on-site or in-the-field applications becomes possible based on the direct (undiluted and untreated) measurement of samples and a rapid, tablet-operated readout system to yield a robust and simple analytical test with superior performance. Testing in real-life scenarios allowed the successful classification and prediction of a number of oil spill samples as well as weathered samples that closely resemble samples collected by first responders. KW - Oil spills KW - Fluorescence KW - PCA KW - Petroleum KW - Rapid test KW - Portable PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595442 DO - https://doi.org/10.1021/acsestwater.3c00648 VL - 4 IS - 2 SP - 621 EP - 627 PB - American Chemical Society (ACS) AN - OPUS4-59544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kislenko, Evgeniia A1 - Incel, A. A1 - Gawlitza, Kornelia A1 - Sellergren, B. A1 - Rurack, Knut T1 - Towards molecularly imprinted polymers that respond to and capture phosphorylated tyrosine epitopes using fluorescent bis-urea and bis-imidazolium receptors N2 - Early detection of cancer is essential for successful treatment and improvement in patient prognosis. Deregulation of post-translational modifications (PTMs) of proteins, especially phosphorylation, is present in many types of cancer. Therefore, the development of materials for the rapid sensing of low abundant phosphorylated peptides in biological samples can be of great therapeutic value. In this work, we have synthesised fluorescent molecularly imprinted polymers (fMIPs) for the detection of the phosphorylated tyrosine epitope of ZAP70, a cancer biomarker. The polymers were grafted as nanometer-thin shells from functionalised submicron-sized silica particles using a reversible addition-fragmentation chain-transfer (RAFT) polymerisation. Employing the combination of fluorescent urea and intrinsically cationic bis-imidazolium receptor cross-linkers, we have developed fluorescent sensory particles, showing an imprinting factor (IF) of 5.0. The imprinted polymer can successfully distinguish between phosphorylated and non-phosphorylated tripeptides, reaching lower micromolar sensitivity in organic solvents and specifically capture unprotected peptide complements in a neutral buffer. Additionally, we have shown the importance of assessing the influence of counterions present in the MIP system on the imprinting process and final material performance. The potential drawbacks of using epitopes with protective groups, which can co-imprint with targeted functionality, are also discussed. KW - Functional monomers KW - Molecularly imprinted polymers KW - Phosphorylated peptides KW - Fluorescence KW - Core-shell particles PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-588089 DO - https://doi.org/10.1039/d3tb01474f SN - 2050-750X SP - 1 EP - 10 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-58808 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sun, Yijuan A1 - Pérez-Padilla, Víctor A1 - Valderrey, Virginia A1 - Bell, Jérémy A1 - Gawlitza, Kornelia A1 - Rurack, Knut T1 - Fluorescence Detection of Perfluoroalkyl Carboxylic Acids with a Miniaturised Assay N2 - 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. T2 - IMA 2023 CY - Chania, Greece DA - 18.09.2023 KW - PFAS KW - MIP KW - Fluorescence KW - Microfluidics KW - Fluorezsenz KW - Mikrofluidik PY - 2023 AN - OPUS4-58527 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Buchholz, Michelle T1 - Dual Fluorescent Molecularly Imprinted Polymers (MIPs) for Detection of the Prevalent Anti-Inflammatory Drug Diclofenac N2 - Ensuring the purity of air and water is essential for the overall well-being of life on earth and the sustainability of the planet's diverse ecosystems. To achieve the goal of zero pollution, as outlined in the 2020 European Green Deal by the European Commission,[1] significant efforts are in progress. A key aspect of this commitment involves advancing more efficient and economically viable methods for treating wastewater. This includes the systematic monitoring of harmful pollutants such as heavy metals, microplastics, pesticides, and pharmaceuticals. One example is the presence of the anti-inflammatory drug diclofenac in water systems, primarily originating from its use as a gel or lotion for joint pain treatment. Diclofenac contamination in surface waters has been detected at approximately 10 μg L-1 (0.03 μM)[2] which is not solely due to widespread usage but also because of the drug's resistance to microbial degradation. Conventional wastewater treatment plants (WWTPs), which rely on biodegradation, sludge sorption, ozone oxidation, and powdered activated carbon treatment, struggle to efficiently remove diclofenac from wastewater.[3],[4] For instance, to enable WWTPs to efficiently monitor and optimize their processes, it would be advantageous to develop on-site detection and extraction methods for persistent pharmaceutical residues in aqueous samples. In this work, a sol-gel process was used to prepare Nile blue-doped silica nanoparticles (dSiO2-NPs) with a diameter of ca. 30 nm that were further functionalized to enable reversible-addition-fragmentation chain-transfer (RAFT) polymerization. To achieve fluorescence detection, a fluorescent monomer was used as a probe for diclofenac in ethyl acetate, generating stable complexes through hydrogen bond formation. The diclofenac/fluorescent monomer complexes were imprinted into thin molecularly imprinted polymer (MIP) shells on the surface of the dSiO2-NPs. Thus, the MIP binding behaviour could be easily evaluated by fluorescence titrations to monitor the spectral changes upon addition of the analyte. Doping the core substrate with Nile blue generates effective dual fluorescent signal transduction. This approach does not solely depend on a single fluorescence emission band in response to analyte recognition. Instead, it enables the fluorescent core to function as an internal reference, minimizing analyte-independent factors such as background fluorescence, instrumental fluctuation, and operational parameters.[5] Rebinding studies showed that the MIP particles have excellent selectivity towards the imprinted template and good discrimination against the competitor ibuprofen, with a discrimination factor of 2.5. Additionally, the limit of detection was determined to be 0.6 μM. Thus, with further optimization of the MIP, there is potential for the development of a MIP-based biphasic extract-&-detect fluorescence assay for simple, sensitive and specific sensing of diclofenac in aqueous samples down to the required concentrations of 0.03 μM. T2 - MIP2024: The 12th International Conference on Molecular Imprinting CY - Verona, Italy DA - 18.06.2024 KW - Sensor KW - Diclofenac KW - Molecularly Imprinted Polymers KW - Fluorescence KW - Pollutant PY - 2024 AN - OPUS4-60439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Climent Terol, Estela A1 - Gotor, Raul A1 - Tobias, Charlie A1 - Bell, Jérémy A1 - Martin-Sanchez, Pedro A1 - Rurack, Knut T1 - Dip Sticks Embedding Molecular Beacon-Functionalized Core−Mesoporous Shell Particles for the Rapid On-Site Detection of Microbiological Fuel Contamination N2 - Microbial contamination of fuels by fungi and bacteria presents risks of corrosion and fuel system fouling. In this work, a rapid test for the determination of microbial genomic DNA from aqueous fuel extracts is presented. It combines test strips coated with polystyrene core/mesoporous silica shell particles, to the surface of which modified fluorescent molecular beacons are covalently grafted, with a smartphone detection system. In the hairpin loop, the beacons incorporate a target sequence highly conserved in all bacteria, corresponding to a fragment of the 16S ribosomal RNA gene, which is also present to a significant extent in the 18S rRNA gene of fungi, allowing for broadband microbial detection. In the developed assay, the presence of genomic DNA extracts from bacteria and fungi down to ca. 20−50 μg L−1 induced a distinct fluorescence response. The optical read-out was adapted for on-site monitoring by combining a 3D-printed case with a conventional smartphone, taking advantage of the sensitivity of contemporary complementary metal oxide semiconductor (CMOS) detectors. Such an embedded assembly allowed to detect microbial genomic DNA in aqueous extracts down to ca. 0.2−0.7 mg L−1 and presents an important step toward the on-site uncovering of fuel contamination in a rapid and simple fashion. KW - Bacteria KW - Fungi KW - Rapid test KW - Fluorescence KW - Smartphone KW - Biofouling PY - 2020 DO - https://doi.org/10.1021/acssensors.0c01178 SN - 2379-3694 VL - 6 IS - 1 SP - 27 EP - 34 PB - American Chemical Society CY - Washington, DC AN - OPUS4-51956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prakash, Swayam T1 - Silane Functionalized Paper Test Strips for Rapid and Sensitive Faecal Pigments Detection towards On-site Water Quality Testing N2 - Introduction. W.H.O estimated that globally at least 2 billion people use drinking water sources contaminated with faeces and according to UNICEF, most of these faecal detection methods are expensive, time-consuming (18–24 h time to result), and, with few exceptions, not suited for on-site analysis. Hence, there is an urgent need for the development of analytical methods that allow to unequivocally test for drinking water quality directly on-site. Aims. Development of rapid and sensitive fluorescence based analytical methods for faecal pigments (FPs) detection towards on-site water quality testing. Methods. Silane functionalized glass fiber paper test strips were developed for the sensitive drop-&-detect analysis of FPs. Drop casting of water samples containing faecal pigment on specifically functionalized test strips allowed the sensitive detection of FPs with a smartphone coupled to a 3D printed optical setup. Results. A series of silanes were used to functionalize glass fiber paper and tune its hydrophobicity, exploiting the influence of matrix tailoring to enhance binding of the Zn salt used as co-reagent to urobilin for optimal fluorescence response. Combination of bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane with zinc chloride-impregnated test strips demonstrated optimum fluorescence response for sensitive (nano- and sub-nanomolar concentration) smartphone-based faecal pigments detection. The obtained fluorescence sensing results were validated with a benchtop fluorometer. Furthermore, the developed analytical method was successfully applied to the analysis of real water samples. Conclusions. The possibilities of matrix tailoring and co-reagent nature on the development of a rapid, sensitive, and embedded fluorescence-based on-site strip test are presented and discussed. This technique has potential application for faecal biomarker detection/primary screening for water quality in developing countries, where sophisticated instruments may not be available. T2 - 18th Conference of Methods and Applications in Fluorescence CY - Valencia, Spain DA - 08.09.2024 KW - Faecal contamination KW - Fluorescence KW - Metal complexes KW - Water analysis PY - 2024 AN - OPUS4-61479 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - López-Puertollano, Daniel A1 - Tobias, Charlie A1 - Bell, Jérémy A1 - Abad-Somovilla, A. A1 - Abad-Fuentes, A. A1 - Rurack, Knut T1 - Superparamagnetic Bead-Based Microfluidic Fluoroimmunoassay Platform for Rapid Ochratoxin A Detection in Flour N2 - Simplification and reduction of time and costs are the primary goals in the development and use of onsite methods in diagnostics and food safety. To facilitate the transition from laboratory techniques to simple, miniaturized devices, we have developed a modular microfluidic platform. This platform integrates a competitive fluorescence immunoassay on the surface of superparamagnetic beads, serving as a complementary technique to traditional cytometry assays. In the first chip module, a fast competitive reaction (5 min) occurs, after which the particles are retained in the second module. This module consists of a PDMS chip and a permanent magnet, allowing only the fluorescent competitor to reach the detection module. Ochratoxin A (OTA) was chosen as the model analyte for device development, using fluorescein-labeled OTA as a competitor. The system efficiently separates particles, with OTA concentration directly correlated to the amount of fluorescent competitor remaining in solution after the competitive reaction. This innovative setup allows to perform rapid measurements with small sample volumes in a short time (10 min), achieving a limit of detection for OTA of 1.2 μg L–1. The system was successfully applied to the accurate determination of OTA in wheat flour spiked at regulatorily relevant concentrations. Using this device, conventional cytometry immunoassays can be seamlessly transformed into user-friendly, miniaturized analytical methods at reduced cost for applications outside of a laboratory directly at the point of need. KW - Bead-based assay KW - Fluorescence KW - Immunoassay KW - Microfluidics KW - mycotoxins PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638472 DO - https://doi.org/10.1021/acssensors.5c01119 SN - 2379-3694 SP - 1 EP - 10 PB - American Chemical Society CY - Washington, D.C. AN - OPUS4-63847 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, Yijuan A1 - Gawlitza, Kornelia A1 - Valderrey, Virginia A1 - Bell, Jérémy A1 - Rurack, Knut T1 - Polymerizable BODIPY probe crosslinker for the molecularly imprinted polymer-based detection of organic carboxylates via fluorescence N2 - This contribution reports the development of a polymerizable BODIPY-type fluorescent probe targeting small-molecule carboxylates for incorporation into molecularly imprinted polymers (MIPs). The design of the probe crosslinker includes a urea recognition site p-conjugated to the 3-position of the BODIPY core and two methacrylate moieties. Titration experiments with a carboxylate-expressing antibiotic, levofloxacin (LEVO), showed a blue shift of the absorption band as well as a broadening and decrease in emission, attributed to hydrogen bonding between the probe’s urea group and the carboxylate group of the antibiotic. Using this probe crosslinker, core–shell particles with a silica core and a thin MIP shell were prepared for the detection of LEVO. The MIP exhibited highly selective recognition of LEVO, with an imprinting factor of 18.1 compared to the non-imprinted polymer. Transmission electron microscopy confirmed the core–shell structure and spectroscopic studies revealed that the receptor’s positioning leads to a unique perturbation of the polymethinic character of the BODIPY chromophore, entailing the favourable responses. These features are fully preserved in the MIP, whereas no such response was observed for competitors such as ampicillin. The sensory particles allowed to detect LEVO down to submicromolar concentrations in dioxane. We have developed here for the first time a BODIPY probe for organic carboxylates and incorporated it into polymers using the imprinting technique, paving the way for BODIPY-type fluorescent MIP sensors. KW - Fluorescence KW - BODIPY probe KW - Molecularly Imprinted Polymers KW - Sensor Materials KW - Dyes KW - Water analysis KW - Advanced materials PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598629 DO - https://doi.org/10.1039/D3MA00476G SP - 1 EP - 11 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - PFAS Sensors N2 - This contribution provides an introduction to the development of sensors for PFAS analysis, presents the most common approaches, and describes the opto-microfluidic strategy in combination with polymerizable indicators and detection matrices currently being pursued by the Chemical and Optical Sensing Division at BAM. T2 - Advancements of Analytical Techniques for Per- and Polyfluoroalkyl Substances (PFAS) – Second Workshop 2023 CY - Berlin, Germany DA - 19.09.2023 KW - PFAS KW - Sensors KW - Molecularly imprinted polymers KW - Microfluidics KW - Fluorescence PY - 2023 AN - OPUS4-58533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Biyikal, Mustafa A1 - Rurack, Knut T1 - Development of a Lab-on-a-Chip for the Detection of Nerve Agents with a Handheld Device N2 - The development of a Lab-on-a-Chip (LoC) is presented, which can detect reactive phosphorous compounds in the gas phase in combination with an optochemical hand-held sensor. The LoC prototype contains three pairs of sensing materials containing fluorescent indicator dyes in various carrier materials. By measuring the fluorescence response to phosphoryl chloride, a surrogate compound, the detection of chemical warfare agents (CWAs) in gas phase becomes possible within seconds, introducing a novel approach to CWA detection. T2 - 2023 IEEE SENSORS Conference CY - Vienna, Austria DA - 29.10.2023 KW - Lab-on-a-Chip KW - Nerve agents KW - Hand-held KW - Fluorescence KW - Toxic industrial chemicals PY - 2023 UR - https://ieeexplore.ieee.org/document/10325263 SN - 979-8-3503-0387-2 DO - https://doi.org/10.1109/SENSORS56945.2023.10325263 SP - 1 EP - 4 PB - IEEE CY - New York AN - OPUS4-59367 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mansurova, Maria A1 - Gotor, Raúl A1 - Johann, Sergej A1 - Neumann, Patrick P. A1 - Bartholmai, Matthias A1 - Rurack, Knut A1 - Bell, Jérémy T1 - Fluorescent Hydrophobic Test Strips with Sterically Integrated Molecular Rotors for the Detection of Hydrocarbons in Water and Soil with an Embedded Optical Read-Out N2 - Contamination of natural bodies of water or soil with oils and lubricants (or generally, hydrocarbon derivatives such as petrol, fuels, and others) is a commonly found phenomenon around the world due to the extensive production, transfer, and use of fossil fuels. In this work, we develop a simple system for the on-field detection of total petroleum hydrocarbons (TPHs) in water and soil. The test is based on the measurement of the fluorescence signal emitted by the molecular rotor 2-[ethyl[4-[2-(4-nitrophenyl)ethenyl]phenyl]amino]ethanol (4-DNS-OH). This dye is embedded in a hydrophobic polymeric matrix (polyvinylidene fluoride), avoiding interactions with water and providing a robust support for use in a test strip fashion. Together with the strips, an embedded optical system was designed for fluorescence signal read-out, featuring a Bluetooth low-energy connection to a commercial tablet device for data processing and analysis. This system works for the detection and quantification of TPHs in water and soil through a simple extraction protocol using a cycloalkane solvent with a limit of detection of 6 ppm. Assays in surface and sea waters were conclusive, proving the feasibility of the method for in-the-field operation. KW - Test strip KW - Sensor KW - Smartphone KW - Fluorescence KW - Test Streifen KW - Sensoren KW - Fluoreszenz KW - Petrol KW - Öl PY - 2023 DO - https://doi.org/10.1021/acs.energyfuels.3c01175 SN - 0887-0624 SP - 1 EP - 6 PB - American Chemical Society CY - Washington, United States AN - OPUS4-57892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - Sensitive and multiplexed assays for point-of-need applications: innovations for robust, reliable, and user-friendly diagnostics N2 - The development of portable analytical assays, particularly during the SARS-CoV-2 pandemic, has revolutionized diagnostics and expanded their use to areas such as food safety, environmental monitoring and forensics. These assays offer the advantage of rapid on-site decision making without the need for laboratory facilities. The omnipresence of mobile devices with advanced cameras and processing power further increases their usability. However, most current assays are limited to detecting single parameters. The challenge now is to develop robust multiplexed assays that can simultaneously detect multiple parameters with high sensitivity. This lecture will present generic approaches developed at BAM with a focus on supramolecular chemistry, luminescence detection, nanomaterials and miniaturization of devices. Examples include mesoporous nanomaterials, gated indicator systems, imprinted polymers, microfluidic devices, test strips and smartphone-based analysis. T2 - Kolloquium Optische Technologien der FH Münster CY - Steinfurt, Germany DA - 18.12.2024 KW - Rapid testing KW - Fluorescence KW - Explosives KW - Environmental contaminants KW - Multiplexing PY - 2024 AN - OPUS4-62322 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - Development of a Lab-on-a-Chip for the Detection of Nerve Agents with a Handheld Device N2 - The development of a Lab-on-a-Chip (LoC) is presented, which can detect reactive phosphorous compounds in the gas phase in combination with an optochemical hand-held sensor. The LoC prototype contains three pairs of sensing materials containing fluorescent indicator dyes in various carrier materials. By measuring the fluorescence response to phosphoryl chloride, a surrogate compound, the detection of chemical warfare agents (CWAs) in gas phase becomes possible within seconds, introducing a novel approach to CWA detection. T2 - IEEE Sensors Conference CY - Vienna, Austria DA - 29.10.2023 KW - Chemical warfare agents KW - Lab-on-a-chip KW - Handheld sensors KW - Toxic industrial chemicals KW - Fluorescence PY - 2023 AN - OPUS4-58815 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hudson, A.D. A1 - Jamieson, O. A1 - Crapnell, R.D. A1 - Rurack, Knut A1 - Soares, T.C.C. A1 - Mecozzi, F. A1 - Laude, A. A1 - Gruber, J. A1 - Novakovic, K. A1 - Peeters, M. T1 - Dual detection of nafcillin using a molecularly imprinted polymer-based platform coupled to thermal and fluorescence read-out N2 - Reported here is the production of molecularly imprinted polymer (MIP) films, integrating a fluorescent moiety that serves as both an element for template interaction and signalling, for the thermal and optical detection of the beta-lactam antibiotic nafcillin. Fluorescein methacrylate (FluMa) was synthesized and introduced during the molecular imprinting process as the sole monomer and in a 1 : 1 mixture with methacrylic acid (MAA), allowing to draw first conclusions on the MIP formation potential of such a rather large and rigid monomer. At first, MIP microparticles containing FluMa were prepared by free radical polymerisation. Optical batch rebinding experiments revealed that FluMa can act as a functional monomer for selective detection of nafcillin; however, the addition of MAA as co-monomer significantly improved performance. Subsequently, thin MIP films containing FluMa were deposited onto functionalised glass slides and the influence of porogen, drying time, and monomer composition was studied. These MIP-functionalised glass electrodes were mounted into a customised 3D-printed flow cell, where changes in the liquid were either evaluated with a thermal device or using fluorescence bright field microscopy. Thermal analysis demonstrated that multiple MIP layers enhanced sensor specificity, with detection in the environmentally relevant range. The fluorescence bright field microscope investigations validated these results, showing an increase in the fluorescence intensity upon exposure of the MIP-functionalised glass slides to nafcillin solutions. These are promising results for developing a portable sensor device that can be deployed for antibiotics outside of a dedicated laboratory environment, especially if sensor design and fluorophore architecture are optimised. KW - Molecularly Imprinted Polymers KW - Fluorescence KW - Antibiotics KW - Heat-transfer Measurements KW - Thin films PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-540044 DO - https://doi.org/10.1039/D1MA00192B VL - 2 IS - 15 SP - 5105 EP - 5115 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-54004 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prakash, Swayam T1 - Development of a Rapid and Sensitive Fluorometric Detection Method for Urobilin Analysis for On-site Water Quality Assessment N2 - The W.H.O. estimated that globally at least 2 billion people use drinking water sources contaminated with faeces and according to UNICEF, most of these faecal contaminants detection methods are expensive, time-consuming (18–24 h time to result), and, with few exceptions, not suited for on-site analysis. Hence, there is an urgent need for the development of rapid analytical methods that allow to unequivocally assess drinking water quality directly on-site. Our approach exploits the weak fluorescence of faecal biomarkers such as urobilin (UB), which is enhanced through complexation with Zn2+ in alcoholic media and is the basis of their detection/estimation, known as Schlesinger’s test.3 However, this method is associated with limitations, as the fluorescence of Zn2+ complexes of UB in water is weak, shows time dependent loss of emission intensity and has strong interference from humic substances that naturally present in surface waters. , To circumvent these issues and achieve the rapid and sensitive on-site detection of FPs, silane-functionalized glass fibre paper test strips were developed following the ‘drop-&-detect’ concept. Drop casting of water samples containing faecal contaminants like UB on specifically functionalized test strips allowed the sensitive detection with a smartphone coupled to a 3D printed optical setup. A series of silanes were used to functionalize glass fibre paper and tune its hydrophobicity, exploiting the influence of matrix tailoring to enhance binding of the Zn2+ salt used as co-reagent to bind UB for optimal fluorometric response. A detection spot was designed by the combination of hydrophilic and hydrophobic silanes with ZnCl2-impregnated test strips. This developed analytical method showed sensitive (nano- and sub-nanomolar concentration) response for UB detection. Furthermore, it can be successfully applied to the analysis of real water samples, allowing for the first time to test for faecal contamination in fresh water directly on-site using a smartphone in only a few minutes, instead of >10 h required for the current standard, i.e., lab-based bacterial tests. T2 - 14th International Conference on Instrumental Methods of Analysis: Modern Trends and Applications CY - Kefalonia, Greece DA - 14.09.2025 KW - Faecal contamination KW - Fluorescence KW - Metal complexes KW - Water analysis KW - Optical and chemical sensing KW - Spectroscopy KW - Onsite analysis KW - Rapid testing PY - 2025 AN - OPUS4-64270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gawlitza, Kornelia T1 - Using Dual Fluorescent Molecularly Imprinted Particles Coupled with a Miniaturized Opto-Microfluidic Platform for On-Site Detection of Perfluoroalkyl Carboxylic Acids N2 - Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic organofluorine chemicals widely used in the production of various materials, including firefighting foams, adhesives, and coatings that resist stains and oil. In recent years, PFAS have gained attention as emerging environmental contaminants, with particular emphasis on perfluoroalkyl carboxylic acids (PFCAs), the most common type of PFAS. PFCAs are defined by a fully fluorinated carbon chain and a charged carboxylic acid group. They have been classified as Substances of Very High Concern and included in the REACH Candidate List due to their persistence, resistance to biodegradation, and toxicological impacts. Traditional methods for analyzing PFCAs, like GC-MS, HRMS, and HPLC-based techniques, are time-consuming, non-portable, expensive, and require specialized expertise. On the other hand, fluorescence assays offer a user-friendly, portable, and cost-effective alternative with high sensitivity and quick results, particularly when the binding of the analyte causes a specific increase in the probe’s fluorescence. Combining these probes with a carrier platform and a miniaturized optofluidic device presents a promising approach for PFCA monitoring. In this study, a new guanidine BODIPY fluorescent indicator monomer was synthesized, characterized, and incorporated into a molecularly imprinted polymer (MIP) designed for the specific detection of perfluorooctanoic acid (PFOA). The MIP layer was formed on silica core nanoparticles doped with tris(bipyridine)ruthenium(II) chloride, serving as an optical internal reference for calibration-free assays. In combination with an extraction step prior to sample analysis, this system enables selective and reliable detection of PFCAs in surface water samples, minimizing interference from competing substances, matrix effects, and other factors. When integrated into an opto-microfluidic setup, the assay provided a compact, user-friendly detection system capable of detecting micromolar levels of PFOA in under 15 minutes from surface water samples. T2 - ANAKON2025 CY - Leipzig, Germany DA - 10.03.2025 KW - Perfluorooctanoic Acid (PFOA) KW - On-site detection KW - Fluorescence KW - Microfluidics KW - Molecularly Imprinted Polymers PY - 2025 AN - OPUS4-62712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prakash, Swayam T1 - Fluorescence Spectroscopy as an Analytical Tool for Rapid and Sensitive Faecal Pigments Detection: From Fundamentals to Onsite Applications N2 - W.H.O estimated that globally at least 2 billion people use drinking water sources contaminated with faeces [1] and according to UNICEF, most of these faecal detection methods are expensive, time-consuming (18–24 h time to result),[2] and, with few exceptions, not suited for on-site analysis.[3] Hence, there is an urgent need for the development of analytical methods that allow to unequivocally test for drinking water quality directly on-site. Today, microbial detection methods primarily targeting E. coli, the major faecal indicator bacteria, are still the prevalent methods for detecting faecal contamination of drinking and recreational waters. As an alternative, Schlesinger proposed the detection of urobilin (UB), a metabolic degradation product of haemoglobin occurring in all mammals, as faecal indicator pigment (FIP) through enhancement of its weak fluorescence by complexation with Zn2+ in alcoholic media already 120 years ago.[4] However, the major limitation of this method is the only weak enhancement of the intrinsically very weak UB fluorescence in aqueous media, requiring either the use of organic solvents or very sensitive instrumentation to reach the relevant detection limits, hampering the method’s use outside of a laboratory environment.[3] In the present work, we addressed the shortcomings relying on interfacial and supramolecular chemistry as well as materials functionalization, transforming Schlesinger’s approach into a fluorometric ‘drop and detect’ assay using a smartphone coupled to a 3D-printed optical setup as a simple and portable device. A series of silanes were used to functionalize glass fibre paper and tune its hydrophobicity, exploiting the influence of matrix tailoring to enhance binding of the Zn salt used as co-reagent to UB for optimal fluorescence response. Combination of bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane and N-octyltrimethoxysilane with ZnCl2-impregnated test strips showed the best response for sensitive (nano- and sub-nanomolar concentration) smartphone-based FIP detection. The obtained fluorescence sensing results were validated with a benchtop fluorometer. Furthermore, the developed analytical method was successfully applied to the analysis of real water samples, allowing for the first time to test for faecal water contamination directly on site in a very short time of few minutes. T2 - Anakon 2025 CY - Leipzig, Germany DA - 10.03.2025 KW - Faecal contamination KW - Fluorescence KW - Metal complexes KW - Water analysis KW - Optical and chemical sensing PY - 2025 AN - OPUS4-62795 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prakash, Swayam T1 - Photophysical Understanding of Urobilin and its Zinc Complexes for Water Quality Testing N2 - Faecal contaminants in water are considered serious threats for human health, due to the presence of viruses, bacteria and other harmful microorganisms.1 Urobilin (UB) is a well-known faecal pigment and can be used as a marker for faecal matter in water.2 UB is commonly present in the urine of all mammals as the catabolic end product of bilirubin degradation.2 As the only simple chemical approach to its detection, Schlesinger’s test is usually used to enhance the weak fluorescence of UB in alcoholic media by complexation with Zinc.2, 3 The major limitation of this method is the only weak enhancement of the intrinsically weak UB fluorescence in aqueous media.3 This work presents an approach to introduce different Zn salts for improved fluorescence response, where we found a clear dependence of the fluorescence yield of UB-Zn(II) complexes on the counterion of the salt in water. By employing a combination of fluorescence parameters like transition energy, fluorescence intensity, and fluorescence lifetime, a photophysical understanding of the structure and conformation of the UB-Zn(II) complexes responsible for the fluorescence enhancement in water could be gained. The possibilities of developing a sensitive analytical method based on the acquired understanding are also discussed. T2 - Central European Conference on Photochemistry CECP 2024 CY - Bad Hofgastein, Austria DA - 18.02.2024 KW - Water analysis KW - Faecal contamination KW - Metal complexes KW - Fluorescence PY - 2024 AN - OPUS4-59874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Biyikal, Mustafa T1 - Development of a handheld device for the trace detection of explosives N2 - This presentation introduces a new explosives trace detector (ETD), a handheld device developed by True Detection Systems (TDS). Addressing the limitations of current handheld detectors—such as unreliable measurements and cumbersome operation— the new ETD XT-1 integrates advanced sensor technology, including a Lab-on-a-Chip, to deliver high sensitivity and accuracy. Capable of detecting trace levels of substances like TNT, TATP, and ammonium nitrate, the device offers rapid, user-friendly detection through AI/ML-enhanced algorithms. These algorithms enable precise substance identification by analyzing absorption and desorption rates, significantly reducing false positives. The XT-1 has broad applications in security, hazardous material detection, and environmental monitoring. T2 - Photonics Days Berlin Brandenburg CY - Berlin, Germany DA - 09.10.2024 KW - Explosives KW - Trace detection KW - Handheld device KW - Lab-on-a-chip KW - Fluorescence PY - 2024 AN - OPUS4-61433 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - Reaction-based BODIPY dyes as powerful tools in fluorescence sensing applications N2 - The reversible analyte-induced switching between a colourless leuco form of a dye and its coloured all-π-conjugated form is one of the oldest concepts in probe- or indicator-based optical analysis,1 constituting so-called “one-color indicators”.2 In contrast to colour changes in the visible region, for which usually a bond-forming or a non-covalent interaction between a functional group on an indicator and an analyte is responsible, the extraordinarily large shifts of 150–250 nm seen for leuco-to-all-π-conjugated transformation are only possible when the reaction takes place directly at a site that is an intrinsic part of a dye’s π-system; the classic case are triphenylmethane dyes.3 Despite its obvious potential, this approach has not been a very popular area of scientific research for decades, perhaps because it is much more difficult to implement selectivity than by modifying terminal functional groups. However, in recent years, reaction-based fluorescence probes have attracted increasing attention by virtue of their superior sensitivity.4,5 Nowadays, rhodamines and fluoresceins are by far the most prominent groups of reaction-based indicators.5 They are usually switched between a colourless and non-fluorescent and a greenish-yellowish absorbing and yellowish-reddish emitting form. Typically, the coloured and fluorescent form is ionic, while the colourless form is neutral, reactions having mainly be designed to occur at the end groups of the xanthenoid π-system. BODIPY dyes, with their favourable spectroscopic and chemical properties as well as facile wavelength tunability features have only very recently been explored into this direction.6,7 Reaction at the core dipyrrin framework of these dyes led to strong colour and fluorescence modulations with potential applications in materials sciences6 and cell imaging.7 The present contribution will highlight the mechanisms at play and the sensing performance realized so far, and will compare core-reactive approaches to reaction-based signalling that involves π-extension of BODIPYs.8,9 T2 - 11th International Conference on Porphyrins and Phthalocyanines (ICPP-11) CY - Online meeting DA - 26.06.2021 KW - Indicators KW - Fluorescence KW - Sensing KW - BODIPY Dyes PY - 2021 AN - OPUS4-54001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jiang, Shan A1 - Gawlitza, Kornelia A1 - Rurack, Knut T1 - Dual-Fluorescent Nanoparticle Probes Consisting of a Carbon Nanodot Core and a Molecularly Imprinted Polymer Shell N2 - 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. KW - Molecular imprinting KW - Fluorescence KW - Core-shell particles KW - Chlorogenic acid KW - Ratiometric measurement PY - 2021 DO - https://doi.org/10.1007/978-1-0716-1629-1_17 VL - 2359 SP - 195 EP - 208 PB - Springer CY - Humana, New York, NY AN - OPUS4-53336 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tobias, Charlie T1 - Dip-stick coated with Polystyrene-Silica Core-Shell particles for the detection of microbiological fuel contamination N2 - The microbial contamination of fuels by fungi or bacteria presents risks such as corrosion and fuel system fouling, which can produce critical problems in refineries and distribution systems and has a significant economic impact at every phase of the process. Many factors have been cited as responsible for microbial growth, like the presence of water in the storage tanks. Indeed, only 1 % water in a storage system is enough for the growth of microorganisms like bacteria or yeasts, as well as for the development of fungal biomass at the oil/water interface.1 In this work, a rapid test for the accurate determination of genomic DNA from aqueous fuel extracts is presented. The detection is based on the employment of polystyrene-mesoporous silica core-shell particles, on which modified fluorescent molecular beacons are covalently grafted. Those beacons incorporate in the hairpin loop a target sequence highly conserved in all bacteria, corresponding to a fragment of the 16S ribosomal RNA subunit. The designed single-stranded molecular beacon contained fluorescein as an internal indicator and a quencher in its proximity when not hybridized. Upon hybridization in presence of the target sequence, the indicator and the quencher are spatially separated, resulting in fluorescence enhancement. To perform the assay the designed particles were disposed on different glass fiber strips to try to achieve a portable and sensitive rapid test. Assays showed that presence of genomic DNA extracts from bacteria down to 50–70 μg L-1 induces a fluorescence response. The optical read-out was adapted for on-site monitoring by adapting a 3D-printed case on a conventional smartphone, taking advantages of the CMOS detector sensitivity.2 Such embedded assembly allowed to detect genomic DNA in aqueous extracts down to the mg L-1 range and presents an interesting step toward on-site monitoring of fuel contamination. T2 - Europtrode 2021 CY - Warsaw, Poland DA - 28.11.2021 KW - Bacgteria KW - Fungi KW - Rapid test KW - Fluorescence KW - Smartphone KW - Biofouling PY - 2021 AN - OPUS4-53867 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wen, Keqing A1 - Gorbushina, Anna A1 - Schwibbert, Karin A1 - Bell, Jérémy T1 - Microfluidic platform with precisely controlled hydrodynamic parameters and integrated features for generation of microvortices to accurately form and monitor biofilms in flow N2 - 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. KW - Topographical pattern KW - E. coli KW - Fluorescence KW - Bacteria trapping KW - Particle velocimetry PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610450 DO - https://doi.org/10.1021/acsbiomaterials.4c00101 SN - 2373-9878 VL - 10 IS - 7 SP - 4626 EP - 4634 PB - ACS Publ. CY - Washington, DC AN - OPUS4-61045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, Yijuan A1 - Pérez-Padilla, Víctor A1 - Valderrey, Virginia A1 - Bell, Jérémy A1 - Gawlitza, Kornelia A1 - Rurack, Knut T1 - Ratiometric detection of perfluoroalkyl carboxylic acids using dual fluorescent nanoparticles and a miniaturised microfluidic platform N2 - The widespread contamination of soil and water with perfluoroalkyl substances (PFAS) has caused considerable societal and scientific concern. Legislative measures and an increased need for remediation require effective on-site analytical methods for PFAS management. Here we report on the development of a green-fluorescent guanidine-BODIPY indicator monomer incorporated into a molecularly imprinted polymer (MIP) for the selective detection of perfluorooctanoic acid (PFOA). Complexation of PFOA by the indicator, which is mediated by concerted protonation-induced ion pairing-assisted hydrogen bonding, significantly enhances fluorescence in polar organic solvents. The MIP forms as a thin layer on silica nanoparticles doped with tris(bipyridine)ruthenium(II) chloride, which provides an orange emission signal as internal reference, resulting in low measurement uncertainties. Using a liquid-liquid extraction protocol, this assay enables the direct detection of PFOA in environmental water samples and achieves a detection limit of 0.11 µM. Integration into an opto-microfluidic system enables a compact and user-friendly system for detecting PFOA in less than 15 minutes. KW - PFAS KW - Molecular imprinting KW - Microfluidics KW - Fluorescence KW - Onsite assay PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650270 DO - https://doi.org/10.1038/s41467-025-66872-9 SN - 2041-1723 VL - 16 IS - 1 SP - 1 EP - 16 PB - Springer Science and Business Media LLC AN - OPUS4-65027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wen, Keqing A1 - Gorbushina, Anna A1 - Schwibbert, Karin A1 - Bell, Jérémy T1 - A microfluidic platform for monitoring biofilm formation in flow under defined hydrodynamic conditions N2 - Bacterial adhesion on surfaces of medical, water and food applications may lead to infections, water or food spoilage and human illness. In comparison to traditional static and macro flow chamber assays for biofilm formation studies, microfluidic chips allow in situ monitoring of biofilm formation under various flow regimes, have better environment control and smaller sample requirements. In this work, a novel microfluidic platform is developed to investigate biofilm adhesion under precisely controlled bacteria concentration, temperature, and flow conditions. This platform central unit is a single-inlet microfluidic flow cell with a 5 mm wide chamber designed and tested to achieve ultra-homogenous flow in the central area of chamber. Within this area, defined microstructures are integrated that will disturb the homogeneity of the flow, thus changing bacterial adhesion pattern. Here we present the monitoring of bacterial biofilm formation in a microfluidic chip equipped with a microstructure known as micro-trap. This feature is based on a 3D bacteria trap designed by Di Giacomo et al. and successfully used to sequester motile bacteria. At first, fluorescent particles similar in size to Escherichia coli (E. coli) are used to simulate bacteria flow inside the flow cell and at the micro-trap. The turbulences induced by the trap are analyzed by imaging and particle tracking velocimetry (PTV). Secondly, the model strain E. coli TG1, ideal and well described for biofilm studies, is used to analyze biofilm formation in the micro-trap. Therefore, a stable fluorescent strain E. coli TG1-MRE-Tn7-141 is constructed by using Tn7 transposon mutagenesis according to the method described by Schlechter et al. Sequestering of E. coli cells within the micro-trap was followed using epifluorescence microscopy. The novel microfluidic platform shows great potential for assessment of bacterial adhesion under various flow regimes. The performance of structural feature with respect to the generation of turbulences that promote or reduce bacterial adhesion can be systematically examined. The combination of flow analysis and fluorescent strain injection into the microfluidic chip shows that the micro-trap is useful for capturing bacteria at defined positions and to study how flow conditions, especially micro-turbulences, can affect biofilm formation. It represents a powerful and versatile tool for studying the relation between topography and bacteria adhesion. T2 - International Conference on Miniaturized Systems for Chemistry and Life Sciences CY - Katowice, Poland DA - 15.10.2023 KW - Biofilm KW - E. coli KW - Microfluidics KW - Velocimetry KW - Fluorescence PY - 2023 AN - OPUS4-59593 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prakash, Swayam A1 - Mishra, Ashok Kumar T1 - Facile Fluorometric Detection of Faecal Pigments: Challenges and Solutions Concerning Water Quality Testing N2 - AbstractDetection and monitoring of faecal contaminants in water is an important component of water quality testing protocol worldwide. However, a systematic overview of the faecal indicator paradigm, including its fundamentals and challenges in analytical applications, is missing. In particular, with respect to the advantages of using faecal indication pigments (FIP) over faecal indication bacteria (FIB). This discussion is based on two FIPs, Urobilin (UB) and Stercobilin (SB), which can enable rapid and real‐time indication of faecal contaminants in ground/surface water. Novel strategies for enhancing sensitive fluorescence‐based techniques for trace concentration detection have been discussed in detail, with specific reference to understanding their physicochemical properties, photophysics, metal‐ligand complexation, molecular aggregations, thermodynamics, fluorescence response and matrix interferences in aqueous media or environmental samples. The insights provided in this perspective article could inspire procedures by avoiding ambiguities and misinterpretations. KW - Faecal contamination KW - Fluorescence KW - Metal complexes KW - Water analysis KW - Optical and chemical sensing KW - Spectroscopy PY - 2025 DO - https://doi.org/10.1002/asia.202401750 SN - 1861-471X SP - 1 EP - 8 PB - Wiley VHC-Verlag AN - OPUS4-63082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - Advanced Onsite Analysis for Point-of-Need Applications: Innovations for Robust, Reliable, and User-Friendly Detection N2 - The advancement of portable analytical assays has transformed onsite analysis in several areas, including food safety, environmental monitoring and forensics. The SARS-CoV-2 pandemic has fueled a need for rapid, onsite solutions that enable immediate decision making without the need for and use of laboratory infrastructure. The integration of mobile devices with advanced cameras and significant computing power improves the accessibility and usability of these tests. However, many current methods are limited to the detection of single parameters. The next challenge is to develop robust multiplexed assays that can analyze multiple parameters simultaneously with high sensitivity. In this lecture, innovative approaches developed at BAM will be presented with a focus on supramolecular chemistry, luminescence detection, nanomaterials and miniaturization of devices. Examples will include mesoporous nanomaterials, gated indicator systems, imprinted polymers, microfluidic devices, test strips and smartphone-based analytical tools, focusing on two use cases, i.e., the detection of contaminants in surface waters and immunoanalytical explosives detection. T2 - International Conference on Emergin Trends in Materials Chemistry CY - Coimbatore, India DA - 03.04.2025 KW - Onsite analysis KW - Rapid tests KW - Mobile devices KW - Supramolecular chemistry KW - Fluorescence PY - 2025 AN - OPUS4-65434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prakash, Swayam A1 - Bell, Jérémy A1 - Rurack, Knut T1 - Rapid Onsite Detection of Fecal Contamination in Water Using a Portable Fluorometric Assay N2 - Fecal pollution in water poses significant health risks, especially when contaminated sources are used for drinking and food production. Traditional water quality testing methods are expensive, slow, and require skilled personnel, limiting their accessibility. This work addresses these issues by developing a portable fluorometric assay for the detection of the fecal indicator pigment urobilin (UB). The assay uses silane-functionalized glass fiber strips impregnated with zinc chloride, providing a ‘drop-&-detect’ approach with enhanced fluorescence response mediated by the unique complexation properties of ZnCl2 and UB. This approach allows for the detection of UB at sub-nanomolar concentrations in less than 1 min using a 3D-printed setup with miniaturized optical components powered by a smartphone with its camera as a detector. The results validated with a benchtop fluorometer show the effectiveness of this method. The successful application of this userfriendly, rapid, and sensitive assay to real water samples from three rivers and the influx and efflux of a wastewater treatment plant advances field-based water quality monitoring, meets the WHO’s ASSURED criteria, and supports progress toward the global clean water and sanitation goals. KW - Fecal pigment KW - Fluorescence KW - Signal amplification KW - Surface chemistry KW - Water quality testing PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655543 DO - https://doi.org/10.1021/acssensors.5c03922 SN - 2379-3694 VL - 11 SP - 1 EP - 9 PB - American Chemical Society CY - Washington, D.C. AN - OPUS4-65554 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hernández-García, María Amparo A1 - Rurack, Knut A1 - Bell, Jérémy T1 - Rapid fabrication of optical elements for sensing applications using a standard SLA printer N2 - The demand for compact, high-performance optical components has driven the development of increasingly sophisticated and miniaturized optical elements, often requiring complex and costly fabrication methods. In this study, we propose a cost-effective and accessible methodology for the fabrication of lenses and free-form optics using a commercially available stereolithography (SLA) 3D printer. A systematic characterisation of six transparent photopolymer resins was conducted in terms of their spectroscopic, optical, and morphological properties, i.e., surface and dimensional properties. The evaluation encompassed parameters such as transmittance, autofluorescence, refractive index, and surface roughness. A straightforward yet resilient printing and post-treatment protocol was formulated, facilitating the fabrication of optical components with over 80% transmittance, minimal intrinsic fluorescence, and surface quality that is compatible with exacting optical applications. The fabricated components demonstrated excellent dimensional fidelity to digital designs and high reproducibility. To demonstrate the versatility of this approach, aspherical, miniaturized, and freeform lenses were designed and integrated into three fluorogenic sensing systems, including oil (strip-based) and chlorine (microfluidic-based) detection platforms, as well as a smartphone-based SARS-CoV-2 biosensor. The integration of customized 3D-printed optics has been demonstrated to enhance signal collection and readout performance, thereby highlighting the potential of this approach to democratize the rapid prototyping and deployment of miniaturized optical systems. This work represents a significant advancement in the field of additive manufacturing, particularly in relation to the development of functional photonic devices. Furthermore, it opens new prospects for sensor applications in biosensing, microfluidics, imaging, and integrated optics. KW - 3D-printing KW - Free-form KW - Prototyping KW - Optical resin KW - Surface finishing KW - Fluorescence KW - Sensor PY - 2026 DO - https://doi.org/10.37188/lam.2026.024 VL - 7 SP - 1 EP - 19 PB - Light Publishing Group CY - Changchun AN - OPUS4-65555 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Costa, Elena A1 - Climent Terol, Estela A1 - Ast, S. A1 - Weller, Michael G. A1 - Canning, J. A1 - Rurack, Knut T1 - Development of a lateral flow test for rapid pyrethroid detection using antibody-gated indicator-releasing hybrid materials N2 - The employment of type-I pyrethroids for airplane disinfection in recent years underlines the necessity to develop sensing schemes for the rapid detection of these pesticides directly at the point-of-use. Antibody-gated indicator-releasing materials were thus developed and implemented with test strips for lateral-flow assay-based analysis employing a smartphone for readout. Besides a proper matching of pore sizes and gating macromolecules, the functionalization of both the material's outer surface as well as the strips with PEG chains enhanced system performance. This simple assay allowed for the detection of permethrin as a target molecule at concentrations down to the lower ppb level in less than 5 minutes. KW - Lateral flow test KW - Gated hybrid material KW - Fluorescence KW - Smartphone readout device KW - Pyrethroid KW - Pesticide KW - Insecticide KW - SBA-15 KW - Permethrin PY - 2020 DO - https://doi.org/10.1039/d0an00319k SN - 0003-2654 SN - 1364-5528 VL - 145 IS - 10 SP - 3490 EP - 3494 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-50756 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hernández García, María Amparo T1 - SAF-based optical biosensor with 3D-printed free-form optics for targeted explosives immuno-detection N2 - Guaranteeing safety and security of citizens requires a significant effort and innovative tools from national and international agencies and governments, especially when it comes to the field of explosives detection. The need to detect Improvised Explosive Devices (IEDs) and Home-made Explosives (HMEs) at a point of suspicion, has grown rapidly due to the ease with which the precursors can be obtained and the reagents synthesised. The limited availability of immunoanalytical tools for HME detection presents an opportunity for the development of new devices, which enable a rapid detection and recognise the target analyte with high specificity and sensitivity. In this work, we introduce an optical biosensor for highly specific and sensitive HME detection. The immunoassay system is placed in a hydrogel environment permeable to the analyte and transparent to light interrogating the fluorescently labelled antibodies. The readout of the immunoanalytical system is realized with Supercritical Angle Fluorescence (SAF), an advanced microscopy technique. To accomplish this, we made use of recent, commercial high resolution (< 22 µm) Liquid Crystal Display 3D printers to fabricate a parabolic optical element with high refractive index (RI>1.5) and transmission values (>90%) from photo-resin. Aiming at a new generation of sensors, which not only can meet the requirements of trace detection, but can also be used for substance identification, the combination of immunoanalytical recognition with SAF detection offers a modularity and versatility that is principally well suitable for the measurements of target analytes at trace levels. T2 - 8th International conference in Biosensing Technology CY - Seville, Spain DA - 12.05.2024 KW - 3D printing KW - Biosensor KW - Fluorescence KW - Explosives PY - 2024 AN - OPUS4-60561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Climent Terol, Estela A1 - Biyikal, Mustafa A1 - Gröninger, Delia A1 - Weller, Michael G. A1 - Martínez Mánez, R. A1 - Rurack, Knut ED - Climent Terol, Estela T1 - Multiplexed Detection of Analytes on Single Test Strips with Antibody-Gated Indicator-Releasing Mesoporous Nanoparticles N2 - Rapid testing methods for the use directly at apointof need are expected to unfold their true potential especiallywhen offering adequate capabilities for the simultaneousmeasurement of multiple analytes of interest. Considering theunique modularity,high sensitivity,and selectivity of antibody-gated indicator delivery (gAID) systems,amultiplexed assayfor three small-molecule explosives (TATP, TNT,PETN) wasthus developed, allowing to detect the analytes simultaneouslywith asingle test strip at lower ppb concentrations in the liquidphase in < 5min using afluorescence reader or asmartphonefor readout. While the TNT and PETN systems were newlydeveloped here,all the three systems also tolerated harshermatrices than buffered aqueous model solutions.Besidesasingle-track strip,the outstanding modularity of the hybridbiosensor materials in combination with strip-patterningtechnologies allowed us to obtain amultichannel strip inastraightforwardmanner,offering comparable analyticalperformance while allowing to be tailored even more to theusersneed. KW - Multiplexing KW - Explosives detection KW - Gated materials KW - Fluorescence PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-518424 DO - https://doi.org/10.1002/anie.202009000 SN - 1433-7851 SN - 1521-3773 VL - 59 IS - 52 SP - 23862 EP - 23869 PB - Wiley-VCH CY - Weinheim AN - OPUS4-51842 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pérez-Padilla, Víctor A1 - Burnage, Samual C. A1 - Wittwer, Philipp A1 - Valderrey, Virginia A1 - Bell, Jérémy A1 - Gawlitza, Kornelia A1 - Rurack, Knut T1 - Detection of Perfluoroalkylic Acids From Water Using a Guanidine-Based Fluorescent Probe and Microfluidic Droplet Extraction N2 - Perfluoroalkylic acids (PFAAs), a subclass of per- and polyfluoroalkyl substances (PFAS), are stable, widely used industrial compounds posing environmental concerns due to their persistence and toxicity. Regulatory actions and remediation strategies necessitate effective onsite analytical methods for PFAS management. We developed an optical sensing system using a fluorescent probe with a benzoxadiazole core and guanidine receptor in a droplet-based microfluidic assay to detect PFAAs in water samples with low detection limits. The PFAAs binding enhances the probe's fluorescence in organic media through protonation-mediated hydrogen bond-assisted ion pairing, exploiting two complementary supramolecular forces. Direct detection employs a liquid-liquid extraction protocol in the microfluidic device, achieving detection limits for PFOA and PFOS down to ≥0.5 µm, with a dynamic range up to 200 µm for sample volumes <100 µL. HCl/KCl buffering facilitates analyte desalting and phase transfer for quantitation from surface water. Additionally, we developed a method involving a thin polymer layer of the probe and a crosslinker on submicron silica particles for direct detection of PFAAs in water. Our approaches provide sensitive, direct recognition and indication of PFAAs, advancing the field beyond indirect sensing and offering improved background suppression, rapid assay times, and a modular design for targeting other PFAS subclasses. KW - PFAS KW - Fluorescence KW - Microfluidics KW - Droplet Extraction PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-657330 DO - https://doi.org/10.1002/adsr.70145 VL - 5 IS - 3 SP - 1 EP - 13 PB - Wiley-VCH CY - Weinheim AN - OPUS4-65733 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -