Wissenschaftliche Artikel der BAM
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- Antibody-gated indicator delivery (1)
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- 1.9 Chemische und optische Sensorik (6) (entfernen)
Vor dem Hintergrund der einzigartigen Modularität, hohen Empfindlichkeit und Selektivität von Antikörper‐gesteuerten Indikatorfreisetzungssystemen (gAID‐Systemen) wurde hier ein Multiplex‐Assay für drei organische Explosivstoffmoleküle (TATP, TNT, PETN) entwickelt, der es erlaubt, die Analyten gleichzeitig in flüssiger Phase mit einem einzelnen Teststreifen und einem Fluoreszenzlesegerät bzw. Smartphone als Detektor in Konzentrationen bis in den unteren ppb‐Bereich in <5 min nachzuweisen. Alle drei Systeme, darunter die hier neu entwickelten Systeme für TNT und PETN, tolerieren zudem nicht nur gepufferte wässrige Modelllösungen, sondern auch komplexere Matrices. Neben einem konventionellen Teststreifen mit einem Kanal erlaubte uns die Anwendung von Wachsdrucktechnologie das Herstellen von mehrkanaligen Streifen mit vergleichbarer analytischer Leistungsfähigkeit, was das enorme Potenzial der modular aufgebauten, hybriden Biosensormaterialien im Hinblick auf eine für den Endanwender maßgeschneiderte Vor‐Ort‐Analytik unterstreicht.
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 theusersneed.
Antibody-gated indicator delivery (gAID) systems based on mesoporous silica nano- and microparticle scaffolds are a promising class of materials for the sensitive chemical detection of small-molecule analytes in simple test formats such as lateral flow assays (LFAs) or microfluidic chips. Their architecture is reminiscent of drug delivery systems, only that reporter molecules instead of drugs are stored in the voids of a porous host particle. In addition, the pores are closed with macromolecular “caps” through a tailored “gatekeeping” recognition chemistry so that the caps are opened when an analyte has reacted with a “gatekeeper”. The subsequent uncapping leads to a release of a large number of indicator molecules, endowing the system with signal amplification features. Particular benefits of such systems are their modularity and adaptability. With the example of the immunochemical detection of type-I pyrethroids by fluorescent dye-releasing gAID systems, the influence of several tuning modes on the optimisation of such hybrid sensory materials is introduced here. In particular, different mesoporous silica supports (from nano- and microparticles to platelets and short fibres), different functionalisation routes and different loading sequences were assessed. The materials’ performances were evaluated by studying their temporal response behaviour and detection sensitivity, including the tightness of pore closure (through the amount of blank release in the absence of analyte) and the release kinetics. Our results indicate that the better the paratope-accommodating Fab region of the antibody “cap” fits into the host material's pore opening, the better the closing/opening mechanism can be controlled. Because such materials are well-suited for LFAs, performance assessment included a test-strip format besides conventional assays in suspension. In combination with dyes as indicators and smartphones for read-out, simple analytical tests for use by untrained personnel directly at a point-of-need such as an aeroplane cabin can be devised, allowing for sensitivities down to the μg kg−1 range in <5 min with case-required selectivities.
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.
Transparent dispersions of hydrophobic SrF2 :Eu3+ nanoparticles in cyclohexane with up to 20% europium were obtained by fluorolytic sol-gel synthesis followed by Phase transfer into cyclohexane through capping with sodium dodecylbenzenesulfonate (SDBS). The particles were characterized by TEM, XRD and DLS as spherical objects with a diameter between 6 and 11 nm in dry state. 1H-13CP MAS NMR experiments revealed the binding of the anionic sulfonate head group to the particle surface. The particles show bright red luminescence upon excitation of the aromatic capping agents, acting as antennas for an Energy transfer from the benzenesulfonate unit to the Eu3+ centers in the particles. This synthesis method overcomes the current obstacle of the fluorolytic sol-gel synthesis that transparent dispersions can be obtained directly only in hydrophilic solvents. To demonstrate the potential of such hydrophobized alkaline-earth fluoride particles, transparent luminescent organic-inorganic composites with 10% SrF2 :Eu3+ embedded into polyTEGDMA, polyBMA, poly-BDDMA and polyD3MA, respectively, were prepared, endowing the polymers with the luminescence features of the nanoparticles.
Spatial heterodyne spectroscopy (SHS) is a novel spectral analysis technique that is being applied for Raman spectroscopy of minerals. This paper presents the theoretical basis of SHS and its application for Raman measurements of calcite, quartz and forsterite in marble, copper ore and nickel ore, respectively. The SHS measurements are done using a broadband (518–686 nm) and resolving power R ≈ 3000 instrument. The spectra obtained using SHS are compared to those obtained by benchtop and modular dispersive spectrometers. It is found that SHRS performance in terms of resolution is comparable to that of the benchtop spectrometer and better than the modular dispersive spectrometer, while the sensitivity of SHRS is worse than that of a benchtop spectrometer, but better than that of a modular dispersive spectrometer. When considered that SHS components are small and can be packaged into a handheld device, there is interest in developing an SHS-based Instrument for mobile Raman spectroscopy. This paper evaluates the possibility of such an application.