1.9 Chemische und optische Sensorik
Filtern
Dokumenttyp
- Zeitschriftenartikel (99)
- Vortrag (71)
- Posterpräsentation (56)
- Beitrag zu einem Tagungsband (6)
- Sonstiges (1)
- Forschungsbericht (1)
Schlagworte
- Fluorescence (47)
- LIBS (29)
- Plasma modeling (26)
- Laser induced plasma (25)
- Plasma diagnostics (20)
- Core-shell particles (17)
- Microfluidics (14)
- Molecularly imprinted polymers (13)
- MIPs (12)
- Sialic acid (10)
- Spectroscopy (10)
- Additive manufacturing (8)
- Laser-induced plasma (8)
- Molecularly Imprinted Polymers (8)
- Roughness (8)
- Multiplexing (7)
- Rapid test (7)
- Cancer (6)
- Signal amplification (6)
- Smartphone (6)
- Vor-Ort-Analytik (6)
- BODIPY (5)
- Fluoreszenz (5)
- Glyphosate (5)
- Image processing (5)
- MamaLoCA (5)
- Molecular imprinting (5)
- Pyrethroids (5)
- Raman spectroscopy (5)
- Schnelltest (5)
- Sensor (5)
- Test strip (5)
- Thermography (5)
- Additive Manufacturing (4)
- Antibiotics (4)
- Antibodies (4)
- BODIPY dyes (4)
- Electron microscopy (4)
- Environment (4)
- Flow cytometry (4)
- Hybrid materials (4)
- Laser metal deposition (4)
- Mikrofluidik (4)
- Nanoparticles (4)
- Optical emission spectroscopy (4)
- Plasma (4)
- Rapid tests (4)
- Sensing (4)
- Tandem MS (4)
- Test strips (4)
- Teststreifen (4)
- Additive Fertigung (3)
- Affinity chromatography (3)
- Air quality (3)
- Analytical Sciences (3)
- Bead-based assay (3)
- Chemical vapor deposition (3)
- Core-Shell Particles (3)
- Core−shell particles (3)
- DPSS laser (3)
- Diclofenac (3)
- Embedded sensor (3)
- Explosives (3)
- Explosives detection (3)
- Fluorescent sensor (3)
- Lateral flow assay (3)
- MIP (3)
- Macrophages (3)
- Mass Spectrometry (3)
- Microfluidic (3)
- Multiplex (3)
- Oil (3)
- Optical sensor (3)
- PFAS (3)
- Plasma physics (3)
- Polyglycerol (3)
- Process control (3)
- Sensors (3)
- Spatial heterodyne spectroscopy (3)
- Thermographie (3)
- Water analysis (3)
- Adulteration (2)
- Air traffic (2)
- Ambient mass spectrometry (2)
- Analytical chemistry (2)
- Anion recognition (2)
- BODIPY dye (2)
- Biofouling (2)
- Biosensors (2)
- Calibration free LIBS (2)
- Charge transfer (2)
- Chemical reactors (2)
- Chlorine (2)
- Cocaine (2)
- Core–shell particles (2)
- Delivery system (2)
- Dip-stick assay (2)
- Direct Energy Deposition (2)
- Drogen (2)
- Electrochemical (2)
- Electron number density (2)
- Embedded system (2)
- Emission line profiles (2)
- Fluorescence sensing (2)
- Fluorescent Probes (2)
- Fluorometric sensing (2)
- Fungi (2)
- Gas sensing (2)
- Gesteuerte Freisetzung (2)
- Glutaraldehyde (2)
- Guanidinium Receptors (2)
- Human papillomavirus (2)
- Image analysis (2)
- Imaging (2)
- Immunoassay (2)
- Immunoassays (2)
- Indikatorfreisetzung (2)
- LMD (2)
- Lab-on-a-chip (2)
- Lab-on-chip (2)
- Laser induced dielectric breakdown (2)
- Laser-Induced Background Spectroscopy (2)
- Laser-Pulver-Auftragschweißen (2)
- Laser-induced breakdown spectroscopy (2)
- Laser-spark (2)
- Lateral Flow Assay (2)
- Lateral Flow Assays (2)
- Lateral flow test (2)
- Mass spectrometry (2)
- Mercury (2)
- Mesoporous materials (2)
- Modeling chemical reactions (2)
- Nerve agents (2)
- PCA (2)
- PH (2)
- Particle characterisation (2)
- Particles (2)
- Permethrin (2)
- Phosphorylated peptides (2)
- Plasma chemistry (2)
- Plasma enhanced chemical vapor deposition (2)
- Plasma processes (2)
- Plasma tomography (2)
- Process monitoring (2)
- Purification (2)
- Raid test (2)
- Reductive amination (2)
- SBA-15 (2)
- SHS (2)
- Sapphire (2)
- Scanning electron microscopy (2)
- Schnelltests (2)
- Sensorik (2)
- Sensorpartikel (2)
- Spatial heterodyne spectrometer (2)
- Spatial information (2)
- Spectrocube (2)
- Sugars (2)
- Temperatures (2)
- Test strip analysis (2)
- Thermal equilibrium (2)
- Thermografie (2)
- Toxic industrial chemicals (2)
- Underwater LIBS (2)
- Water (2)
- Water quality (2)
- Wireless mobile sensor device (2)
- 2,4-D (1)
- 3D image analysis (1)
- 3D-Mikrofluidik (1)
- 3D-printing (1)
- Acoustic Emission (1)
- Acoustic levitation (1)
- Adsorbed microgel particles (1)
- Advanced materials (1)
- Affinity extraction (1)
- Affinity support (1)
- Aggregates (1)
- Agricultural economy (1)
- Airborne (1)
- Aluminum oxide (1)
- Ambient Desorption/Ionization (1)
- Ambient desorption/ionization (1)
- Ambient ionization (1)
- Ambient pressure laser ionization (1)
- Amino acid analysis (1)
- Ammonia (1)
- Ammoniak (1)
- Ammunition (1)
- Amoxicillin (1)
- Amperometry (1)
- Amplification (1)
- Anilinopyridine (1)
- Anion receptors (1)
- Antibody (1)
- Antibody purification (1)
- Antibody-gated indicator delivery (1)
- Antibody-gated indicator delivery systems (1)
- Antibody-gated materials (1)
- Antifouling surface (1)
- Antikörper (1)
- Aptamere (1)
- Aromatic amino acid analysis AAAA (1)
- Aromatic amino acid analysis aaaa (1)
- Atomic (1)
- Autophagy (1)
- BODIPY Dyes (1)
- BODIPY probe (1)
- BODIPYs (1)
- BSA (1)
- BaF (1)
- Bacgteria (1)
- Bacteria (1)
- Batch analysis (1)
- Bead-based assays (1)
- Benzin (1)
- Benzoxadiazole dyes (1)
- Bio-gated hybrid materials (1)
- Biochemische Sensoren (1)
- Bioconjugation (1)
- Biofilm (1)
- Biomarker (1)
- Biosensor (1)
- Bioseparation (1)
- BornAgain simulation (1)
- Boron halides (1)
- Boronic acid (1)
- Bovine serum albumin (1)
- CF LIBS algorithms (1)
- CF-LIBS (1)
- CID (1)
- Caffeine (1)
- Calcite (1)
- Calibration-free LIBS (1)
- Cancer cells (1)
- Cannibal Drug (1)
- Carbamazepine (1)
- Carbon Nanodots (1)
- Carrier (1)
- Cellulose (1)
- Cement (1)
- Cement-based materials (1)
- Characterization (1)
- Charge Transfer (1)
- Charged dyes (1)
- Chemical derivatization (1)
- Chemical warfare agents (1)
- Chemical-hydrodynamic modeling (1)
- Chlor (1)
- Chlorofluorosilanes (1)
- Chlorogenic acid (1)
- Cobaloxime complex (1)
- Cocaine detection (1)
- Collision-induced dissociation (1)
- Colorimetric Test (1)
- Concentration mapping (1)
- Concrete (1)
- Corundum (1)
- Cucurbituril (1)
- Cyanide (1)
- Cyanide detection (1)
- Cyclometalated iridium (III) complexes (1)
- Cytometry (1)
- Cytotoxicity (1)
- DNA (1)
- DOTA (1)
- DPSS-laser (1)
- Dendrimer (1)
- Deuterium (1)
- Deuterium enriched water (1)
- Device embedding (1)
- Devices (1)
- Diesel (1)
- Digital holographic cytometry (1)
- Digital holographic microscopy (1)
- Double-pulse laserinduced breakdown spectroscopy (1)
- Downstream processing (1)
- Drogenanalytik (1)
- Droplets (1)
- Drug delivery (1)
- Dual-color labeling glycan (1)
- Dual-pulse (1)
- Durchflusszytometrie (1)
- Dye loading optimisation (1)
- Dye monomers (1)
- Dye release (1)
- Dyes (1)
- Dyes/pigments (1)
- E. coli (1)
- ELISA (1)
- ESEM (1)
- Electrochemiluminiscence (1)
- Elektrochemie (1)
- Elektrochemilumineszenz (1)
- Emerging pollutants (1)
- Emission spectroscopy (1)
- Emmbedded sensor (1)
- Environmental monitoring (1)
- Equilibrium chemical modeling (1)
- Etofenprox (1)
- Excimers (1)
- Explosiven (1)
- Explosives determination (1)
- Faecal contamination (1)
- Farbstoffe (1)
- Fast Fourier Transform (1)
- Fiber-optic laser-induced breakdown spectroscopy (FO-LIBS) (1)
- Field test (1)
- Fluorescence detection (1)
- Fluorescence sensor (1)
- Fluorescent MIPs (1)
- Fluorescent Urea Receptors (1)
- Fluorescent dye (1)
- Fluorescent dyes (1)
- Fluorescent probes (1)
- Fluorescent sensors (1)
- Fluorezsenz (1)
- Fluorides (1)
- Fluorophores (1)
- Forsterite (1)
- Fourier transform spectroscopy (1)
- Fragmentation (1)
- Fragmentation activation (1)
- Fuel adulteration (1)
- Functional monomers (1)
- Gamma-hydroxybutyric acid (1)
- Gas analysis (1)
- Gas sensor (1)
- Gasoline (1)
- Gated delivery systems (1)
- Gated hybrid material (1)
- Gated hybrid materials (1)
- Gated materials (1)
- Gesteuerten Nanopartikeln (1)
- Glycan (1)
- Glycans (1)
- Grain size (1)
- Grazing incidence small-angle neutron scattering (1)
- Group profile (1)
- Guanidine benzoxadiazole (1)
- Guanidine receptor (1)
- Guanidinium receptors (1)
- HCD (1)
- Hand-held (1)
- Handheld device (1)
- Handheld sensors (1)
- Heat-transfer Measurements (1)
- Heterologous hapten (1)
- High repetition rate (1)
- High repetition-rate (1)
- Holographic microscopy (1)
- Human plasma (1)
- Hydrodynamic model (1)
- Hydrogen reduction (1)
- Hyperbranched polymer (1)
- ICP MS (1)
- IR-Spektroskopie (1)
- IR-spectroscopy (1)
- Igg (1)
- Immunassay (1)
- Immunochemical response optimization (1)
- Immunoglobulins (1)
- Immunoprecipitation (1)
- Immunosensor (1)
- Imprinting (1)
- Indicator displacement assay (1)
- Indicators (1)
- Inductively coupled plasma (1)
- Infrared Thermography (1)
- Insecticide (1)
- Interferometric spectroscopy (1)
- Ion mobility (1)
- Ionmobility spectrometry (1)
- Iron Complex (1)
- Kerosene (1)
- Kokain (1)
- Lab-on-a-Chip (1)
- Lanthanide (1)
- Laser (1)
- Laser ablation (1)
- Laser induced breakdown (1)
- Laser induced dielectric breakdown, Hydrogen reduction (1)
- Laser induced plasma deposition (1)
- Laser metal deposition (LMD) (1)
- Laser-Induced Breakdown Spectroscopy (LIBS) (1)
- Laser-Induced Plasma (1)
- Laser-Pulver-Auftragschweißen (LPA) (1)
- Laser-spark ionization (1)
- Laserauftragschweißen (1)
- Lasers (1)
- Lateral flow assays (1)
- Lateral flow tests (1)
- Linker (1)
- Luminescent lifetime (1)
- Lysosome (1)
- MC-LIBS (1)
- Magnetic Particles (1)
- Magnetic beads (1)
- Magnetophoresis (1)
- MamaLoCa (1)
- Mesoporous particles (1)
- Mesoporous silica (1)
- Metal complexes (1)
- Metal labeling (1)
- Micro-Hydrocyclone (1)
- Microbial (1)
- Microfluidic Chip (1)
- Mikrobiell (1)
- Mikroskopie (1)
- Mixed surface (1)
- Modeling (1)
- Molecular Imprinting (1)
- Molecular analysis (1)
- Molecular dynamics simulations (1)
- Molecular emission (1)
- Molecularly Imprinted Polymer (1)
- Molybdenum (1)
- Molybdenum carbide (1)
- Monitoring (1)
- Multigassensorik (1)
- Multiplexed assay (1)
- Multiplexing detection (1)
- Munition (1)
- NDT (1)
- Nanoparticle formation (1)
- Neutral dyes (1)
- Neutron reflectometry (1)
- Nomaterials (1)
- Nonspecific binding (NSB) (1)
- Oil analysis (1)
- Oil spills (1)
- Oligonucleotide (1)
- Optical Emission Spectroscopy (1)
- Optical detection (1)
- Optical sensing (1)
- Optically active surfaces (1)
- Optics (1)
- Optische Emissionsspektroskopie (1)
- Optische Emissionsspektroskopie (OES) (1)
- Organic-inorganic hybrid composites (1)
- PFOA (1)
- Parameter optimization (1)
- Particle Characterization (1)
- Particle characterization (1)
- Particle size (1)
- Partikeln (1)
- Penicillin (1)
- Perfluorooctanoic Acid (PFOA) (1)
- Periodate oxidation (1)
- Pesticide (1)
- Pesticides (1)
- Pestizid (1)
- Petrol (1)
- Petroleum (1)
- Phenothrin (1)
- Phospholipids (1)
- Phosphonic acids (1)
- Phosphorylated Tyrosine (1)
- Photoinduced Electron Transfer (1)
- Photophysics (1)
- Photopolymerization (1)
- Plasma chemical reactor (1)
- Plasma expansion (1)
- Plasma imaging (1)
- Plasma induced luminescence (1)
- Plasma-induced luminescence (1)
- Pollutant (1)
- Polymer nanolayers (1)
- Polymerwissenschaften (1)
- Portable (1)
- ProMoAM (1)
- Proinflammatory cytokines (1)
- Protein (1)
- Protein a (1)
- Protein hydrolysis (1)
- Protein immobilization (1)
- Protein quantification (1)
- Prozessmonitoring (1)
- Pyrethroid (1)
- Pyrethroids detection (1)
- Quartz (1)
- RF ICP discharge (1)
- Radon reconstruction (1)
- Radon transformation (1)
- Rapid prototyping (1)
- Rapid testing (1)
- Rapid testing methods (1)
- Rare-Earth elements (Tm3+) (1)
- Ratiometric measurement (1)
- Rational design (1)
- Real-time imaging (1)
- Reduction of MoF6 (1)
- Reduction of volatile chlorides and fluorides by hydrogen (1)
- Ring fusion (1)
- SA conjugates (1)
- SAFIA (1)
- SBA-16 (1)
- SDS-PAGE (1)
- SEM (1)
- SEM tilting (1)
- Schallemission (1)
- Schallemissionsanalyse (SEA) (1)
- Scientific communication (1)
- Scientific method (1)
- Scientific rigour (1)
- Scopolamine (1)
- Self-absorption coefficient (1)
- Self-assembled monolayer (SAM) (1)
- Self-assembled monolayers (SAM) (1)
- Sensor Materials (1)
- Sensoren (1)
- Sensory particles (1)
- Shadowgraphy (1)
- Silica (1)
- Silicon halides (1)
- Smartphone readout (1)
- Smartphone readout device (1)
- Sol-gel process (1)
- Solid phase (1)
- Solid-phase extraction (SPE) (1)
- Spatial Heterodyne Spectrometer (1)
- Spatial Heterodyne Spectroscopy (1)
- Spectral enhancement (1)
- Speichel (1)
- Splitting (1)
- Start-up (1)
- Stimulated Raman Spectroscopy (1)
- Sulfide sensing (1)
- Supramolecular Chemistry (1)
- Surface area control (1)
- Surface coating (1)
- Surface group quantification (1)
- Surfactants (1)
- Suspension Array (1)
- TATP (1)
- TEM (1)
- TNT (1)
- Tandem-MS (1)
- Test Streifen (1)
- Test Strip analysis (1)
- Test gas generation (1)
- Thermal model (1)
- Thermodynamic (1)
- Thin films (1)
- Tilting (1)
- Time-of-flight secondary ion mass spectrometry (1)
- Titanium dioxide (1)
- ToF-SIMS (1)
- Trace analysis (1)
- Trace detection (1)
- Type-I pyrethroids (1)
- Tyrosine (1)
- UV/vis spectroscopy (1)
- Ultrasonic acoustic resonator (1)
- Ultrasonic levitation (1)
- Ultrasound (1)
- Urin (1)
- Vacuum Ultraviolet (1)
- Vacuum ultraviolet (VUV) light (1)
- Velocimetry (1)
- Wasser (1)
- X-ray photoelectron spectroscopy (1)
- Zellanalytik (1)
- Zellulose (1)
- agricultural economy (1)
- embedded sensor (1)
- environment (1)
- fluorescence (1)
- gas analysis (1)
- ion optics (1)
- spectroscopy (1)
- transmission mode (1)
- µJ-DPSS laser (1)
- Öl (1)
Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (234)
- 1.9 Chemische und optische Sensorik (234)
- 8 Zerstörungsfreie Prüfung (29)
- 6 Materialchemie (21)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (17)
- 1.5 Proteinanalytik (16)
- 1.8 Umweltanalytik (12)
- P Präsident (12)
- 8.0 Abteilungsleitung und andere (11)
- 9 Komponentensicherheit (11)
Paper des Monats
- ja (3)
Eingeladener Vortrag
- nein (71)
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.
Per- and polyfluoroalkyl substances (PFAS) represent a class of synthetic organofluorine chemicals extensively utilized in the manufacturing of various materials such as firefighting foams, adhesives, and stain- and oil-resistant coatings. In recent years, PFAS have been considered as emerging environmental contaminants, with particular focus on perfluoroalkyl carboxylic acids (PFCAs), the most prevalent type among PFAS. PFCAs are characterized by a fully fluorinated carbon backbone and a charged carboxylic acid headgroup. Notably, they have been designated as Substances of Very High Concern and added to the REACH Candidate List due to their persistence in the environment, non-biodegradability and toxicological effects.
Conventional techniques for the analysis of PFCA, such as GC-MS, HRMS and HPLC-based methods, are laborious, not portable, costly and require skilled personnel. In contrast, fluorescence assays can be designed as easy-to-operate, portable and cost-effective methods with high sensitivity and fast response, especially when analyte binding leads to a specific increase of a probe’s emission. Integration of such probes with a carrier platform and a miniaturized optofluidic device affords a promising alternative for PFCA monitoring.
Here, a novel guanidine BODIPY fluorescent indicator monomer has been synthesized, characterized, and incorporated into a molecularly imprinted polymer (MIP) for the specific detection of perfluorooctanoic acid (PFOA). The MIP layer was formed on tris(bipyridine)ruthenium(II) chloride doped silica core particles for optical internal reference and calibration-free assays. Such system allows selective and reliable detection of PFCA from surface water samples, with minimum interference by competitors, matrix effects and other factors. Integration of the assay into an opto-microfluidic setup resulted in a miniaturized and easy-to-operate detection system allowing for micromolar detection of PFOA in less than 15 minutes from surface water sample.
Optical biosensors often show remarkable performance and can be configured in many ways for sensitive, selective, and rapid measurements. However, the high-quality and advanced optical assemblies required to read out the sensor signals, for example, Total Internal Reflection Fluorescence (TIRF) or Supercritical Angle Fluorescence (SAF) microscopy, which necessitate complex and expensive optical elements. Particularly in optical method development, researchers or developers are often confronted with limitations because conventional manufacturing processes for optical elements can be restrictive in terms of design, material, time, and cost. Modern and high-resolution 3D printing techniques make it possible to overcome these challenges and enable the fabrication of individualized and personalized free-form optical components, which can reduce costs and significantly shorten the prototyping timeline—from months to hours. In this work, we use a modern, high-resolution (< 22 µm) commercial Liquid Crystal Display (LCD)-based 3D printer, for which we spectroscopically and physically characterized commercial photo-resins printable with the LCD technique in the first step (Figure 1). The aim was not only to produce a printed element with a high surface quality that mitigates the inner filter effects caused by attenuation (high optical density (OD) due to reflection and scattering), but also to select a material with a high refractive index (RI>1.5) and high transmission values (>90% transmittance) in the visible to near-infrared spectral range (approx. 450 – 900 nm) that exhibits little or no autofluorescence. Using a selection of suitable resins, lenses and free-form optical elements were manufactured for comparison with standard glass or plastic counterparts.
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.
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.
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.
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.
Luminescence lifetimes are an attractive analytical method for detection due to its high sensitivity and stability. Iridium probes exhibit luminescence with long excited-state lifetimes, which are sensitive to the local environment. Perfluorooctanoic acid (PFOA) is listed as a chemical of high concern regarding its toxicity and is classified as a “forever chemical”. In addition to strict limits on the presence of PFOA in drinking water, environmental contamination from industrial effluent or chemical spills requires rapid, simple, accurate, and cost-effective analysis in order to aid containment. Herein, we report the fabrication and function of a novel and facile luminescence sensor for PFOA based on iridium modified on gold surfaces. These surfaces were modified with lipophilic iridium complexes bearing alkyl chains, namely, IrC6 and IrC12, and Zonyl-FSA surfactant. Upon addition of PFOA, the modified surfaces IrC6-FSA@Au and IrC12-FSA @Au show the largest change in the red luminescence signal with changes in the luminescence lifetime that allow monitoring of PFOA concentrations in aqueous solutions. The platform was tested for the measurement of PFOA in aqueous samples spiked with known concentrations of PFOA and demonstrated the capacity to determine PFOA at concentrations >100 μg/L (240 nM).
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.
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.
Superparamagnetic hybrid polystyrene-core silica-shell beads have emerged as promising alternatives to traditional in flow cytometry-based competitive antibody assays [1]. These materials consist of a polystyrene core and a silica shell, in which magnetic nanoparticles are embedded, facilitating the handling and retention in tests. The outer silica surface allows for easy modification through silane chemistry, allowing the attachment of antibodies, or other molecules of interest. Ochratoxin A (OTA), a mycotoxin that can be found in grain products, coffee, cacao, or grapes, was chosen as the main target analyte to detect [2]. In this study, previously in house produced anti-OTA antibodies [3] were attached to the surface of the particles and the whole system was used as detection entity. In a first approach, the system was used for the development of a competitive cytometry assay using an OTA-fluorescein (OTA-F) adduct as competitor and marker. In this assay the fluorescence emitted by the OTA-F competitor on the surface of the particle was detected at a wavelength of 518 nm using a 533/30.H filter and was correlated to the forward scatter (FSC) to distinguish it from the excess of competitor still in solution. Under optimised conditions, the final assay showed a limit of detection of 0.03 nM. In a second approach, a simplified ready-to-inject fluidic system was built based on a laser (488 nm) and a photomultiplier detector to measure the signal of competitor still in solution. The competition step was carried out in a vial and the whole mixture was injected into the fluidic system. To avoid signal scattering, the particles were separated in-line using a magnet and only the OTA-F competitor still in solution was detected, reaching a limit of detection of 1.2 nM. With the aim to reduce user manipulation, the final assay is still under development for in-line incubation during the competitive step.
In particular, the rapid development of lateral flow assays as indispensable tools for everyone to contain the SARS-CoV-2 pandemic has fuelled the global demand for analytical tests that can be used outside dedicated laboratories. In addition to their use in medical diagnostics, rapid tests and assays have become increasingly important in various fields such as food safety, security, forensics, and environmental management. The advantage is obvious: taking the assay directly to the sample minimizes the time between suspicion and decision-making, allowing faster action. Especially today, when mobile communication devices with powerful computing capabilities and built-in cameras are ubiquitous, more people than ever before around the world have the basic skills to operate a powerful detector at their fingertips. This sets the stage for a much wider use of analytical measurements in terms of prognosis and prevention, enabling professional laypersons in particular.
However, current strip-based systems are primarily focused on single parameter analysis, whether it is SARS-CoV-2 biomarkers, blood glucose levels, or lead concentrations in water samples. Industrial applications of such methods also often still rely on single-parameter assays, requiring multiple runs even for a limited number of key parameters. Overcoming these limitations depends on developing low-number multiplexing strategies that ensure robustness, reliability, speed, ease of use, and sensitivity.
This lecture will give an overview of several generic approaches developed in recent years to address these challenges. It will highlight how the synergy of supramolecular (bio)chemistry, luminescence detection, hybrid (nano)materials and device miniaturization can result in powerful (bio)analytical assays that can be used at a point-of-need.1-5 Selected examples will introduce key aspects of such systems that include tailored signaling mechanisms and recognition elements, materials functionalization and device integration, including hybrid nanomaterials, gated indicator release systems, strip modification, and smartphone-based analysis.
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.
With the help of the EXIST research transfer the startup True Detection System (TDS) will develop a portable and easy-to-use handheld device based on chemical-optical sensors that can detect the smallest traces of various explosives and markers (e.g. TNT, C4, ANFO, TATP, DMDNB, etc.) and pure salts (e.g. potassium nitrate) reliably and without major cross-sensitivities. The device has been developed over the last 10 years at the Federal Institute for Material Research and Testing (BAM) in cooperation with an SME. Within the next 18 months, a laboratory prototype will now be converted into a commercial device.
PFAS Sensors
(2023)
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.
Silica materials are popular in biomedical applications as composites and drug delivery platforms due to their low toxicity and biocompatibility. Mesoporous silica nanoparticles are attractive drug delivery systems based on their porous silica framework with high surface area. In the preparation of mesoporous silica frameworks, most commonly, MCM-41, the efficient removal of the template responsible for introducing porous networks, cetyltrimethyl ammonium bromide (CTAB), is a critical step due to the template’s high toxicity in the environment and human health. In this work, we present a new one-pot approach of introducing challenging antibiotics within a silica framework without the need of toxic templates, but instead using micelle formation by an antibacterial agent. We demonstrate that micelles formed by cetylpyridinium chloride (CPC), a known antibacterial agent, entrap antibiotics such as rifampicin and ciprofloxacin. Extensive NMR studies elucidate the precise localisation of the antibiotic within the CPC micelle. Ciprofloxacin is placed between the outer and palisade region while rifampicin is located further into the hydrophobic CPC micelle core. In both cases, the formation of the silica framework can be built around the CPC-antibiotic loaded micelles. The resulting silica nanoparticles show loading of both CPC and antibiotic agents, porosity and dual antibacterial release upon disruption of the micelle within the silica framework. The design not only provides a strategy of a therapeutic design to form porous frameworks but also highlights the potential of precise antibiotic dose and release in nanoparticle systems.
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.
Microbial contamination of fuels by fungi or bacteria poses risks such as corrosion and fuel system fouling, which can lead to critical problems in refineries and distribution systems and has a significant economic impact at every stage of the process. Many factors have been cited as being responsible for microbial growth, like the presence of water in the storage tanks. In fact, only 1 % water in a storage system is sufficient for the growth of microorganisms like bacteria or yeasts, as well as for the development of fungal biomass at the oil/water interface.
This work presents a rapid test for the accurate determination of genomic DNA from aqueous fuel extracts. The detection is based on the use of polystyrene-mesoporous silica core-shell particles onto which modified fluorescent molecular beacons are covalently grafted. These beacons contain 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 developed particles were deposited on different glass fibre strips to obtain a portable and sensitive rapid test. The assays showed that the presence of genomic DNA extracts from bacteria down to 50–70 μg L–1 induced a fluorescence response. The optical read-out was adapted for on-site monitoring by fitting a 3D-printed case to a conventional smartphone, taking advantages of the sensitivity of the CMOS detector. Such embedded assembly enabled the detection of genomic DNA in aqueous extracts down to the mg L–1 range and represents an interesting step toward on-site monitoring of fuel contamination.
Immunoassays, based on the recognition and capture of analytes by highly selective antibodies, are now used extensively in all areas of diagnostics, but the challenge is to further integrate them into online sensors. To improve the transition from laboratory immunoassays to immunosensors, we have developed a complete flow system, based on a microfluidic core flow cell to enable automated detection of one of the most commonly used immunoassay substrates, TMB, by chronoamperometry. The architecture and fluidic optimisation of the system showed that a specially designed 3D flow cell allows higher flow rates (500 μL min−1) than a standard enlarged microfluidic channel (50 μL min−1) resulting in a significantly shorter detection time of 30 seconds per sample and making the system more robust against interferences due to bubble formation in the chip. The electrochemical measurements showed an improved signal-to-noise ratio (SNR) and thus higher sensitivity for a model immunoassay for diclofenac (SNR = 59), compared to the analytical performance of a conventional laboratory microplate-based assay with optical detection (SNR = 19). In general, this system facilitates the conversion of any conventional immunoassay into an immunosensor with automatic and continuous detection.
Rapid tests and assays to be used outside of a laboratory for non-trained personal and also at a point of need are becoming increasingly important in areas such as health, food, security, or the environment. Specially on that regard, paper-based sensors are emerging as a new class of devices because they fulfil the requisites of the "World Health Organization" to be ASSURED: affordable, sensitive, specific, user-friendly, rapid and robust, equipment free and deliverable to end-users. The physical, chemical and mechanical properties of cellulose or glass fiber paper in combination with the facility of preparation are making these materials of great interest while looking for cost-efficient and green alternatives for device production technologies. To improve the sensitivity of these systems, a particularly promising approach is the employment of gated indicator delivery systems using preorganized nanoscopic solid structures incorporated on paper strips to produce an exponential amplification of the detectable signal. Having in mind these concepts, several examples of (bio)gated materials incorporated into sensing membranes will be presented for the detection of small organic molecules, having fluorescence or electrochemiluminescence signal as output signal. Compared with fluorescence, it has been demonstrated that the non-optical excitation has significantly reduced the background signal, and with the help of a portable potentiostat in combination with a home-made 3D-printed case fitted onto a smartphone, the sensitivity of the sensing system has been improved tremendously, from the lower ppb range (fluorescence) to the lower ppt range. With this study, the applicability of ECL detection on paper strips in combination with gated indicator-releasing materials has been demonstrated for the first time, presenting a novel synergistic match. Considering the modularity of the system developed, the platform technology potential is obvious, promising expansion of the general concept to many other analytes, applications and scenarios.