Dip Sticks Embedding Molecular Beacon-Functionalized Core–Mesoporous Shell Particles for the Rapid On-Site Detection of Microbiological Fuel Contamination

Abstract

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.

Combining Electrochemiluminescence Detection with Aptamer‐Gated Indicator Releasing Mesoporous Nanoparticles Enables ppt Sensitivity for Strip‐Based Rapid Tests

“…Having established the sensing behaviour in solution, we moved towards applicability and incorporated the hybrid particles with modified glass fibre strips. Based on previous work in which we have shown that the chemical functionalization of a test strip matrix can significantly improve assay performance,[ 27a , 43 ] we also went through several matrix tailoring cycles by sterically adsorbing or covalently anchoring PEG and N ‐alkyldiethanolamine moieties on the fibres to arrive at the best material used here. Whereas the PEG moieties preserve the stability of the sensing material MMRAA in the paper matrix and facilitate the transport of Ru(bpy) 3 2+ due to a reduction of the electrostatic interaction of the positively charged dye with a net negatively charged silanol‐ and silanolate‐expressing surface of the glass fibre paper, the N ‐alkyldiethanolamine groups enhance the ECL signal of the dye.…”

Streifenschnelltest mit ppt‐Empfindlichkeit durch Kombination von Elektrochemilumineszenz‐Detektion mit Aptamer‐gesteuerter Indikatorfreisetzung aus mesoporösen Nanopartikeln

“…Nachdem wir das Nachweisverhalten in Lösung etabliert hatten, unternahmen wir den nächsten Schritt in Richtung Anwendung und integrierten die Hybridpartikel in modifizierte Glasfaserstreifen. Basierend auf früheren Arbeiten, in denen wir gezeigt haben, dass die chemische Funktionalisierung einer Teststreifenmatrix die Assayleistung signifikant verbessern kann, [27a,43] wurde die Matrix in mehreren Zyklen durch die sterische Adsorption oder kovalente Verankerung von PEG‐ und N‐Alkyldiethanolamin‐Einheiten an den Fasern optimiert, um zum besten hier verwendeten Material zu gelangen. PEG‐Einheiten bewahren die Stabilität des Sensormaterials MMRAA in der Papiermatrix und ermöglichen den Transport von Ru(bpy) 3 2+ durch eine Verringerung der elektrostatischen Wechselwirkung des positiv geladenen Farbstoffs mit einer netto negativ geladenen Silanol‐ bzw.…”

Generalized Analysis Approach of the Profile Roughness by Electron Microscopy with the Example of Hierarchically Grown Polystyrene–Iron Oxide–Silica Core–Shell–Shell Particles

“…In particular, micrometer‐sized beads are well suited for the quantitative detection of analytes of interest by single particle‐based (bio)analytical methods because of their rapid reaction kinetics and the requirement of small sample volumes, an area of application we became interested in over the past years. [ 10–14 ] A very promising material combination for single particle‐based assays is achieved by merging the benefits of polystyrene (PS) and silica (SiO 2 ) particles in a core–shell particle format. [ 12,15,16 ]…”

“…In particular, micrometer-sized beads are well suited for the quantitative detection of analytes of interest by single particle-based (bio)analytical methods because of their rapid reaction kinetics and the requirement of small sample volumes, an area of application we became interested in over the past years. [10][11][12][13][14] A very promising material combination for single particle-based assays is achieved by merging the benefits of polystyrene (PS) and silica (SiO 2 ) particles in a core-shell particle format. [12,15,16] Besides equipping CS particles with optical or electrochemical features and grafting (bio)chemical units to their outer surface that drive many of the developments in the field, two less explicit aspects gained increasing attention recently, surface morphology and its impact on functional performance [10,17,18] as well as magnetic properties, strongly facilitating handling and processibility [19,20] especially in view of automated workflows.…”