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- ItemRapid isolation and identification of pneumonia associated pathogens from sputum samples combining an innovative sample preparation strategy and array-based detection(Washington : American Chemical Society, 2019) Pahlow, Susanne; Lehniger, Lydia; Hentschel, Stefanie; Seise, Barbara; Braun, Sascha D.; Ehricht, Ralf; Berg, Albrecht; Popp, Jürgen; Weber, KarinaWith this study, an innovative and convenient enrichment and detection strategy for eight clinically relevant pneumonia pathogens, namely, Acinetobacter baumannii, Escherichia coli, Haemophilus influenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae is introduced. Bacteria were isolated from sputum samples with amine-modified particles exploiting pH-dependent electrostatic interactions between bacteria and the functionalized particle surface. Following this, an asymmetric polymerase chain reaction as well as subsequent stringent array-based hybridization with specific complementary capture probes were performed. Finally, results were visualized by an enzyme-induced silver nanoparticle deposition, providing stable endpoint signals and consequently an easy detection possibility. The assay was optimized using spiked samples of artificial sputum with different strains of the abovementioned bacterial species. Furthermore, actual patient sputum samples with S. pneumoniae were successfully analyzed. The presented approach offers great potential for the urgent need of a fast, specific, and reliable isolation and identification platform for important pneumonia pathogens, covering the complete process chain from sample preparation up to array-based detection within only 4 h.With this study, an innovative and convenient enrichment and detection strategy for eight clinically relevant pneumonia pathogens, namely, Acinetobacter baumannii, Escherichia coli, Haemophilus influenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae is introduced. Bacteria were isolated from sputum samples with amine-modified particles exploiting pH-dependent electrostatic interactions between bacteria and the functionalized particle surface. Following this, an asymmetric polymerase chain reaction as well as subsequent stringent array-based hybridization with specific complementary capture probes were performed. Finally, results were visualized by an enzyme-induced silver nanoparticle deposition, providing stable endpoint signals and consequently an easy detection possibility. The assay was optimized using spiked samples of artificial sputum with different strains of the abovementioned bacterial species. Furthermore, actual patient sputum samples with S. pneumoniae were successfully analyzed. The presented approach offers great potential for the urgent need of a fast, specific, and reliable isolation and identification platform for important pneumonia pathogens, covering the complete process chain from sample preparation up to array-based detection within only 4 h.
- ItemDistinction of nucleobases - A tip-enhanced Raman approach(Frankfurt, M. : Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2011) Treffer, R.; Lin, X.; Bailo, E.; Deckert-Gaudig, T.; Deckert, V.The development of novel DNA sequencing methods is one of the ongoing challenges in various fields of research seeking to address the demand for sequence information. However, many of these techniques rely on some kind of labeling or amplification steps. Here we investigate the intrinsic properties of tip-enhanced Raman scattering (TERS) towards the development of a novel, label-free, direct sequencing method. It is known that TERS allows the acquisition of spectral information with high lateral resolution and single-molecule sensitivity. In the presented experiments, single stranded adenine and uracil homopolymers were immobilized on different kinds of substrates (mica and gold nanoplates) and TERS experiments were conducted, which demonstrated the reproducibility of the technique. To elucidate the signal contributions from the specific nucleobases, TERS spectra were collected on single stranded calf thymus DNA with arbitrary sequence. The results show that, while the Raman signals with respect to the four nucleobases differ remarkably, specific markers can be determined for each respective base. The combination of sensitivity and reproducibility shows that the crucial demands for a sequencing procedure are met.
- ItemTowards multiple readout application of plasmonic arrays(Frankfurt, M. : Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2011) Cialla, D.; Weber, K.; Böhme, R.; Hübner, U.; Schneidewind, H.; Zeisberger, M.; Mattheis, R.; Möller, R.; Popp, J.In order to combine the advantages of fluorescence and surface-enhanced Raman spectroscopy (SERS) on the same chip platform, a nanostructured gold surface with a unique design, allowing both the sensitive detection of fluorescence light together with the specific Raman fingerprint of the fluorescent molecules, was established. This task requires the fabrication of plasmonic arrays that permit the binding of molecules of interest at different distances from the metallic surface. The most efficient SERS enhancement is achieved for molecules directly adsorbed on the metallic surface due to the strong field enhancement, but where, however, the fluorescence is quenched most efficiently. Furthermore, the fluorescence can be enhanced efficiently by careful adjustment of the optical behavior of the plasmonic arrays. In this article, the simultaneous application of SERS and fluorescence, through the use of various gold nanostructured arrays, is demonstrated by the realization of a DNA detection scheme. The results shown open the way to more flexible use of plasmonic arrays in bioanalytics.
- ItemTowards Bacteria Counting in DI Water of Several Microliters or Growing Suspension Using Impedance Biochips(Basel : MDPI, 2020) Kiani, Mahdi; Tannert, Astrid; Du, Nan; Hübner, Uwe; Skorupa, Ilona; Bürger, Danilo; Zhao, Xianyue; Blaschke, Daniel; Rebohle, Lars; Cherkouk, Charaf; Neugebauer, Ute; Schmidt, Oliver G.; Schmidt, HeidemarieWe counted bacterial cells of E. coli strain K12 in several-microliter DI water or in several-microliter PBS in the low optical density (OD) range (OD = 0.05–1.08) in contact with the surface of Si-based impedance biochips with ring electrodes by impedance measurements. The multiparameter fit of the impedance data allowed calibration of the impedance data with the concentration cb of the E. coli cells in the range of cb = 0.06 to 1.26 × 109 cells/mL. The results showed that for E. coli in DI water and in PBS, the modelled impedance parameters depend linearly on the concentration of cells in the range of cb = 0.06 to 1.26 × 109 cells/mL, whereas the OD, which was independently measured with a spectrophotometer, was only linearly dependent on the concentration of the E. coli cells in the range of cb = 0.06 to 0.50 × 109 cells/mL.
- ItemModified bibenzimidazole ligands as spectator ligands in photoactive molecular functional Ru-polypyridine units? Implications from spectroscopy(Cambridge : RSC, 2014) Meyer-Ilse, J.; Bauroth, S.; Bräutigam, M.; Schmitt, M.; Popp, J.; Beckert, R.; Rockstroh, N.; Pilz, T.D.; Monczak, K.; Heinemann, F.W.; Rau, S.; Dietzek, B.The photophysical properties of Ruthenium-bipyridine complexes bearing a bibenzimidazole ligand were investigated. The nitrogens on the bibenzimidazole-ligand were protected, by adding either a phenylene group or a 1,2-ethandiyl group, to remove the photophysical dependence of the complex on the protonation state of the bibenzimidazole ligand. This protection results in the bibenzimidazole ligand contributing to the MLCT transition, which is experimentally evidenced by (resonance) Raman scattering in concert with DFT calculations for a detailed mode assignment in the (resonance) Raman spectra.
- ItemRuthenium(II)-bis(4'-(4-ethynylphenyl)-2,2':6', 2''-terpyridine) - A versatile synthon in supramolecular chemistry. Synthesis and characterization(Warsaw : Central European Science Journals, 2011) Siebert, R.; Schlütter, F.; Winter, A.; Presselt, M.; Görls, H.; Schubert, U.S.; Dietzek, B.; Popp, J.A homoleptic ethynyl-substituted ruthenium(II)-bisterpyridine complex representing a versatile synthon in supramolecular chemistry was synthesized and analyzed by NMR spectroscopy, mass spectrometry and X-ray diffractometry. Furthermore, its photophysical properties were detailed by UV/Vis absorption, emission and resonance Raman spectroscopy. In order to place the results obtained in the context of the vast family of ruthenium coordination compounds, two structurally related complexes were investigated accordingly. These reference compounds bear either no or an increased chromophore in the 4̀-position. The spectroscopic investigations reveal a systematic bathochromic shift of the absorption and emission maximum upon increasing chromophore size. This bathochromic shift of the steady state spectra occurs hand in hand with increasing resonance Raman intensities upon excitation of the metal-to-ligand charge-transfer transition. The latter feature is accompanied by an increased excitation delocalization over the chromophore in the 4̀-position of the terpyridine. Thus, the results presented allow for a detailed investigation of the electronic effects of the ethynyl substituent on the metal-to-ligand charge-transfer states in the synthon for click reactions leading to coordination polymers.
- ItemEffect of novel quercetin titanium dioxide-decorated multi-walled carbon nanotubes nanocomposite on Bacillus subtilis biofilm development(Basel : MDPI, 2018) Raie, Diana S.; Mhatre, Eisha; El-Desouki, Doaa S.; Labena, Ahmed; El-Ghannam, Gamal; Farahat, Laila; Youssef, Tareq; Fritzsche, Wolfgang; Kovács, ÁkosThe present work was targeted to design a surface against cell seeding and adhering of bacteria, Bacillus subtilis. A multi-walled carbon nanotube/titanium dioxide nano-power was produced via simple mixing of carbon nanotube and titanium dioxide nanoparticles during the sol-gel process followed by heat treatment. Successfully, quercetin was immobilized on the nanocomposite via physical adsorption to form a quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite. The adhesion of bacteria on the coated-slides was verified after 24 h using confocal laser-scanning microscopy. Results indicated that the quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite had more negativity and higher recovery by glass surfaces than its counterpart. Moreover, coating surfaces with the quercetin-modified nanocomposite lowered both hydrophilicity and surface-attached bacteria compared to surfaces coated with the multi-walled carbon nanotubes/titanium dioxide nanocomposite.
- ItemModified powder-in-tube technique based on the consolidation processing of powder materials for fabricating specialty optical fibers(Basel : MDPI AG, 2014) Auguste, J.-L.; Humbert, G.; Leparmentier, S.; Kudinova, M.; Martin, P.-O.; Delaizir, G.; Schuster, K.; Litzkendorf, D.The objective of this paper is to demonstrate the interest of a consolidation process associated with the powder-in-tube technique in order to fabricate a long length of specialty optical fibers. This so-called Modified Powder-in-Tube (MPIT) process is very flexible and paves the way to multimaterial optical fiber fabrications with different core and cladding glassy materials. Another feature of this technique lies in the sintering of the preform under reducing or oxidizing atmosphere. The fabrication of such optical fibers implies different constraints that we have to deal with, namely chemical species diffusion or mechanical stress due to the mismatches between thermal expansion coefficients and working temperatures of the fiber materials. This paper focuses on preliminary results obtained with a lanthano-aluminosilicate glass used as the core material for the fabrication of all-glass fibers or specialty Photonic Crystal Fibers (PCFs). To complete the panel of original microstructures now available by the MPIT technique, we also present several optical fibers in which metallic particles or microwires are included into a silica-based matrix.
- ItemTopUp SERS substrates with integrated internal standard(Basel : MDPI, 2018) Patze, Sophie; Hübner, Uwe; Weber, Karina; Cialla-May, Dana; Popp, JürgenSurface-enhanced Raman spectroscopy (SERS) is known as a molecular-specific and highly sensitive method. In order to enable the routine application of SERS, powerful SERS substrates are of great importance. Within this manuscript, a TopUp SERS substrate is introduced which is fabricated by a top-down process based on microstructuring as well as a bottom-up generation of silver nanostructures. The Raman signal of the support material acts as an internal standard in order to improve the quantification capabilities. The analyte molecule coverage of sulfamethoxazole on the surface of the nanostructures is characterized by the SERS signal evolution fitted by a Langmuir–Freundlich isotherm.
- ItemResonance Raman Spectro-Electrochemistry to Illuminate Photo-Induced Molecular Reaction Pathways(Basel : MDPI, 2019) Zedler, Linda; Krieck, Sven; Kupfer, Stephan; Dietzek, BenjaminElectron transfer reactions play a key role for artificial solar energy conversion, however, the underlying reaction mechanisms and the interplay with the molecular structure are still poorly understood due to the complexity of the reaction pathways and ultrafast timescales. In order to investigate such light-induced reaction pathways, a new spectroscopic tool has been applied, which combines UV-vis and resonance Raman spectroscopy at multiple excitation wavelengths with electrochemistry in a thin-layer electrochemical cell to study [RuII(tbtpy)2]2+ (tbtpy = tri-tert-butyl-2,2′:6′,2′′-terpyridine) as a model compound for the photo-activated electron donor in structurally related molecular and supramolecular assemblies. The new spectroscopic method substantiates previous suggestions regarding the reduction mechanism of this complex by localizing photo-electrons and identifying structural changes of metastable intermediates along the reaction cascade. This has been realized by monitoring selective enhancement of Raman-active vibrations associated with structural changes upon electronic absorption when tuning the excitation wavelength into new UV-vis absorption bands of intermediate structures. Additional interpretation of shifts in Raman band positions upon reduction with the help of quantum chemical calculations provides a consistent picture of the sequential reduction of the individual terpyridine ligands, i.e., the first reduction results in the monocation [(tbtpy)Ru(tbtpy•)]+, while the second reduction generates [(tbtpy•)Ru(tbtpy•)]0 of triplet multiplicity. Therefore, the combination of this versatile spectro-electrochemical tool allows us to deepen the fundamental understanding of light-induced charge transfer processes in more relevant and complex systems.