1,721,398 research outputs found
Dual detection of the explosives TATP (triacetone triperoxide) and TNT (trinitrotoluene) using antiboby-gated mesoporous silicia materials
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Integration of novel specific gated hybrid materials into versatile platforms for advanced sensing applications
No full textPhotophysical Understanding of Urobilin and its Zinc Complexes for Water Quality Testing
No full textFaecal 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
Hybrid Core-Shell Particles in Diagnostic Applications - a versatile platform for multiplexed cytometric bead assays
No full textMultiplexed bead-based array formats play an increasingly important role in analytical laboratories. Due to the high surface-to-volume ratio, fast reaction kinetics and modular assay design, these sensor formats are applied in clinical diagnostic, drug development and classical biosensors with great success.
As the spherical platform, researchers utilize micron sized particles made from polymeric or silica material. Such beads are commercially available from vendors such as BD or Luminex. However, we have encountered several problematic issues which accompany these platforms: first, bigger sized beads, which are required for particle handling reasons, are difficult to prepare with high monodispersity - a key requirement for cytometric application. Second, plain beads, made from either polymer or silica, have each several disadvantages such as inferior scattering properties in case of silica or limited flexibility for coupling strategies in the case of latex beads.
In order to overcome this problem, we have developed a versatile core-shell (CS) platform which consists of a polymeric core with a structurally controlled silica shell. In our approach, the core building block can be easily prepared with high yields and high monodispersity in a dispersion polymerization from approximately 500 nm to 1.3 µm. Then, silica is coated in a classical sol-gel process to protect the core with a stable yet modifiable surface (see SEM image in Figure 1, platform). Here, we combine ideal scattering properties and easy preparation of the polymeric core with the chemical flexibility of a silica surface. Moreover, the additional shell domain adds density to the composite, which makes particle handling feasible also for nanometer sized beads.
In this contribution we present proof-of-principle results of competitive immunoassays with fluorescence detection using our CS beads – each performed in mix-and-read fashion without washing steps. All sizes are applicable in cytometric read-out which and can be used for size encoding (see Set 1 to 3 in Figure 1, size encoding). However, further multiplexing for a set of at least 20 parameters can be achieved by swelling hydrophobic dyes into the core. To the same time, precise tuning of the surface with mixed silane layers allowed us to improve the selectivity towards small molecules in competitive immunoassays significantly (see example in Figure 1, Application). We believe that our platform allows researchers to gain access to superior assay performance in combination with a low-threshold approach for the synthesis of the spherical platform
Preparation of core-shell microparticles for single particle detection in suspension arrays
No full textFluorescence Spectroscopy as an Analytical Tool for Rapid and Sensitive Faecal Pigments Detection: From Fundamentals to Onsite Applications
No full textW.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
Handgerät für den mobilen Einsatz zur Detektion von Sprengstoffspuren
No full textMithilfe des EXIST-Forschungstransfers wird ein tragbares und leicht zu bedienendes Handgerät auf der Basis von chemisch-optischen Sensoren entwickelt, welches kleinste Spuren von verschiedensten Sprengstoffen und Markern (z.B. TNT, C4, ANFO, TATP, DMDNB etc.) und reine Salze (z. B. Kaliumnitrat) sicher und ohne größere Querempfindlichkeiten detektieren kann. Das Gerät wurde in den letzten 10 Jahren bei der Bundesanstalt für Materialforschung und -prüfung (BAM) entwickelt und wird von der 2024 ausgegründeten Firma Noxoon GmbH in ein kommerzielles Gerät überführt.
Die Vorteile des Handgeräts sind die hohe Selektivität, die hohe Sensitivität, die schnelle Detektion in wenigen Sekunden bis zur Ergebnisanzeige sowie der schnelle und das geringe Gewicht des Gerätes von 900 g.
Neben den Vorteilen findet sich auch zahlreiche Alleinstellungsmerkmale in der Benutzung des Gerätes. So können z.B.
- reine Salze
- Sprengstoffe in Gegenwart von Wasser
- Sprengstoffe und Drogen in versiegelten Briefumschlägen detektiert werden.
Ein besonderes Alleinstellungsmerkmal ist, dass eine Reinigung des Handgeräts nach Messungen von stark kontaminierten Proben nicht notwendig ist.
Für den deutschsprachigen bzw. europäischen Raum existiert noch kein vergleichbares Gerät.
Das kommerzielle Gerät soll ab 2025 auf den Markt gebracht werden und wird einen wichtigen Beitrag zur öffentlichen Sicherheit und zum Umweltschutz leisten
Development of a Rapid and Sensitive Fluorometric Detection Method for Urobilin Analysis for On-site Water Quality Assessment
No full textThe 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
Dual-fluorescent sialic acid-imprinted polymer nanoparticles for staining of glycans on cancerous cells
No full textCancer is a leading cause of death worldwide, and its early detection and resultant treatment contributes significantly to patient recovery and survival. Detection is currently based on magnetic resonance imaging and computed tomography, methods that are expensive, while processing of the results is time-consuming1. There is a need for low-cost cancer detection techniques that give conclusive results in the shortest time possible. When equipped with a reporter function, molecularly imprinted polymers (MIPs) targeting tumor markers on cancerous cells may provide a cheaper solution for imaging-based cancer detection. Thin MIP layers immobilized on particle platforms are ideal in this regard, because a fluorescence reporter can be integrated into the particle core and/or MIP shell and such core/shell nanoparticles show faster response times and increased selectivity in comparison to bulk MIPs.
Changes in sialylation patterns of cell surface glycans indicate malignancy2. Here, we present the development of MIPs that target sialic acid-terminated glycans (SA MIPs), prepared as a thin layer on a polystyrene core/silica shell nanoparticle platform. The MIP particles contain fluorescent emitters and can be applied in fluorescence imaging of malignant tumors. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) are used for structural characterization. Binding capacity of the MIPs to target glycans and competing sugars is also evaluated and compared to that of the corresponding non-imprinted polymer particles (NIP)
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