419 results
Search Results
Now showing 1 - 10 of 419
- ItemBiochemical Characterization of Mouse Retina of an Alzheimer's Disease Model by Raman Spectroscopy(Washington, DC : ACS Publications, 2020) Stiebing, Clara; Jahn, Izabella J.; Schmitt, Michael; Keijzer, Nanda; Kleemann, Robert; Kiliaan, Amanda J.; Drexler, Wolfgang; Leitgeb, Rainer A.; Popp, JürgenThe presence of biomarkers characteristic for Alzheimer's disease in the retina is a controversial topic. Raman spectroscopy offers information on the biochemical composition of tissues. Thus, it could give valuable insight into the diagnostic value of retinal analysis. Within the present study, retinas of a double transgenic mouse model, that expresses a chimeric mouse/human amyloid precursor protein and a mutant form of human presenilin 1, and corresponding control group were subjected to ex vivo Raman imaging. The Raman data recorded on cross sections of whole eyes highlight the layered structure of the retina in a label-free manner. Based on the Raman information obtained from en face mounted retina samples, a discrimination between healthy and Alzheimer's disease retinal tissue can be done with an accuracy of 85.9%. For this a partial least squares-linear discriminant analysis was applied. Therefore, although no macromolecular changes in form of, i.e., amyloid beta plaques, can be noticed based on Raman spectroscopy, subtle biochemical changes happening in the retina could lead to Alzheimer's disease identification. ©
- 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.
- ItemPresent and future of surface-enhanced Raman scattering(Washington, DC : ACS Publications, 2020) Langer, Judith; de Aberasturi, Dorleta Jimenez; Aizpurua, Javier; Alvarez-Puebla, Ramon A.; Auguié, Baptiste; Baumberg, Jeremy J.; Bazan, Guillermo C.; Bell, Steven E.J.; Boisen, Anja; Brolo, Alexandre G.; Choo, Jaebum; Cialla-May, Dana; Deckert, Volker; Fabris, Laura; Faulds, Karen; de Abajo, F. Javier García; Goodacre, Royston; Graham, Duncan; Haes, Amanda J.; Haynes, Christy L.; Huck, Christian; Itoh, Tamitake; Käll, Mikael; Kneipp, Janina; Kotov, Nicholas A.; Kuang, Hua; Le Ru, Eric C.; Lee, Hiang Kwee; Li, Jian-Feng; Ling, Xing Yi; Maier, Stefan A.; Mayerhöfer, Thomas; Moskovits, Martin; Murakoshi, Kei; Nam, Jwa-Min; Nie, Shuming; Ozaki, Yukihiro; Pastoriza-Santos, Isabel; Perez-Juste, Jorge; Popp, Juergen; Pucci, Annemarie; Reich, Stephanie; Ren, Bin; Schatz, George C.; Shegai, Timur; Schlücker, Sebastian; Tay, Li-Lin; Thomas, K. George; Tian, Zhong-Qun; Van Duyne, Richard P.; Vo-Dinh, Tuan; Wang, Yue; Willets, Katherine A.; Xu, Chuanlai; Xu, Hongxing; Xu, Yikai; Yamamoto, Yuko S.; Zhao, Bing; Liz-Marzán, Luis M.The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.
- ItemRapid Colorimetric Detection of Pseudomonas aeruginosa in Clinical Isolates Using a Magnetic Nanoparticle Biosensor(Washington, DC : ACS Publications, 2019) Alhogail, Sahar; Suaifan, Ghadeer A.R.Y; Bikker, Floris J.; Kaman, Wendy E.; Weber, Karina; Cialla-May, Dana; Popp, Jürgen; Zourob, Mohammed M.A rapid, sensitive, and specific colorimetric biosensor based on the use of magnetic nanoparticles (MNPs) was designed for the detection of Pseudomonas aeruginosa in clinical samples. The biosensing platform was based on the measurement of P. aeruginosa proteolytic activity using a specific protease substrate. At the N-terminus, this substrate was covalently bound to MNPs and was linked to a gold sensor surface via cystine at the C-terminus of the substrates. The golden sensor appears black to naked eyes because of the coverage of the MNPs. However, upon proteolysis, the cleaved peptide–MNP moieties will be attracted by an external magnet, revealing the golden color of the sensor surface, which can be observed by the naked eye. In vitro, the biosensor was able to detect specifically and quantitatively the presence of P. aeruginosa with a detection limit of 102 cfu/mL in less than 1 min. The colorimetric biosensor was used to test its ability to detect in situ P. aeruginosa in clinical isolates from patients. This biochip is anticipated to be useful as a rapid point-of-care device for the diagnosis of P. aeruginosa-related infections.
- ItemStatistical Analysis of Scanning Fluorescence Correlation Spectroscopy Data Differentiates Free from Hindered Diffusion(Washington, DC : Soc., 2018-7-20) Schneider, Falk; Waithe, Dominic; Lagerholm, B. Christoffer; Shrestha, Dilip; Sezgin, Erdinc; Eggeling, Christian; Fritzsche, MarcoCells rely on versatile diffusion dynamics in their plasma membrane. Quantification of this often heterogeneous diffusion is essential to the understanding of cell regulation and function. Yet such measurements remain a major challenge in cell biology, usually due to low sampling throughput, a necessity for dedicated equipment, sophisticated fluorescent label strategies, and limited sensitivity. Here, we introduce a robust, broadly applicable statistical analysis pipeline for large scanning fluorescence correlation spectroscopy data sets, which uncovers the nanoscale heterogeneity of the plasma membrane in living cells by differentiating free from hindered diffusion modes of fluorescent lipid and protein analogues.
- ItemRapid detection of the aspergillosis biomarker triacetylfusarinine C using interference-enhanced Raman spectroscopy(Berlin ; Heidelberg : Springer, 2020) Pahlow S.; Orasch T.; Žukovskaja O.; Bocklitz T.; Haas H.; Weber K.Triacetylfusarinine C (TAFC) is a siderophore produced by certain fungal species and might serve as a highly useful biomarker for the fast diagnosis of invasive aspergillosis. Due to its renal elimination, the biomarker is found in urine samples of patients suffering from Aspergillus infections. Accordingly, non-invasive diagnosis from this easily obtainable body fluid is possible. Within our contribution, we demonstrate how Raman microspectroscopy enables a sensitive and specific detection of TAFC. We characterized the TAFC iron complex and its iron-free form using conventional and interference-enhanced Raman spectroscopy (IERS) and compared the spectra with the related compound ferrioxamine B, which is produced by bacterial species. Even though IERS only offers a moderate enhancement of the Raman signal, the employment of respective substrates allowed lowering the detection limit to reach the clinically relevant range. The achieved limit of detection using IERS was 0.5 ng of TAFC, which is already well within the clinically relevant range. By using an extraction protocol, we were able to detect 1.4 μg/mL TAFC via IERS from urine within less than 3 h including sample preparation and data analysis. We could further show that TAFC and ferrioxamine B can be clearly distinguished by means of their Raman spectra even in very low concentrations. © 2020, The Author(s).
- ItemDiscrimination between pathogenic and non-pathogenic E. coli strains by means of Raman microspectroscopy(Berlin ; Heidelberg : Springer, 2020) Lorenz B.; Ali N.; Bocklitz T.; Rösch P.; Popp J.Bacteria can be harmless commensals, beneficial probiotics, or harmful pathogens. Therefore, mankind is challenged to detect and identify bacteria in order to prevent or treat bacterial infections. Examples are identification of species for treatment of infection in clinics and E. coli cell counting for water quality monitoring. Finally, in some instances, the pathogenicity of a species is of interest. The main strategies to investigate pathogenicity are detection of target genes which encode virulence factors. Another strategy could be based on phenotypic identification. Raman spectroscopy is a promising phenotypic method, which offers high sensitivities and specificities for the identification of bacteria species. In this study, we evaluated whether Raman microspectroscopy could be used to determine the pathogenicity of E. coli strains. We used Raman spectra of seven non-pathogenic and seven pathogenic E. coli strains to train a PCA-SVM model. Then, the obtained model was tested by identifying the pathogenicity of three additional E. coli strains. The pathogenicity of these three strains could be correctly identified with a mean sensitivity of 77%, which is suitable for a fast screening of pathogenicity of single bacterial cells. [Figure not available: see fulltext.]. © 2020, The Author(s).
- ItemPlasmon induced deprotonation of 2-mercaptopyridine(Cambridge : Royal Society of Chemistry, 2020) Singh P.; Deckert-Gaudig T.; Zhang Z.; Deckert V.Surface plasmons can provide a novel route to induce and simultaneously monitor selective bond formation and breakage. Here pH-induced protonation, followed by plasmon-induced deprotonation of 2-mercaptopyridine was investigated using surface- and tip-enhanced Raman scattering (SERS and TERS). A large difference in the deprotonation rate between SERS and TERS will be demonstrated and discussed with respect to hot-spot distribution. © 2020 The Royal Society of Chemistry.
- ItemCharacterisation of Methicillin-Resistant Staphylococcus aureus from Alexandria, Egypt(Basel : MDPI, 2023) Monecke, Stefan; Bedewy, Amira K.; Müller, Elke; Braun, Sascha D.; Diezel, Celia; Elsheredy, Amel; Kader, Ola; Reinicke, Martin; Ghazal, Abeer; Rezk, Shahinda; Ehricht, RalfThe present study aims to characterise clinical MRSA isolates from a tertiary care centre in Egypt’s second-largest city, Alexandria. Thirty isolates collected in 2020 were genotypically characterised by microarray to detect their resistance and virulence genes and assign them to clonal complexes (CC) and strains. Isolates belonged to 11 different CCs and 14 different strains. CC15-MRSA-[V+fus] (n = 6), CC1-MRSA-[V+fus+tir+ccrA/B-1] (PVL+) (n = 5) as well as CC1-MRSA-[V+fus+tir+ccrA/B-1] and CC1153-MRSA-[V+fus] (PVL+) (both with n = 3) were the most common strains. Most isolates (83%) harboured variant or composite SCCmec V or VI elements that included the fusidic acid resistance gene fusC. The SCCmec [V+fus+tir+ccrA/B-1] element of one of the CC1 isolates was sequenced, revealing a presence not only of fusC but also of blaZ, aacA-aphD and other resistance genes. PVL genes were also common (40%). The hospital-acquired MRSA CC239-III strain was only found twice. A comparison to data from a study on strains collected in 2015 (Montelongo et al., 2022) showed an increase in fusC and PVL carriage and a decreasing prevalence of the CC239 strain. These observations indicate a diffusion of community-acquired strains into hospital settings. The beta-lactam use in hospitals and the widespread fusidic acid consumption in the community might pose a selective pressure that favours MRSA strains with composite SCCmec elements comprising mecA and fusC. This is an unsettling trend, but more MRSA typing data from Egypt are required.
- ItemSuperelasticity of Plasma- and Synthetic Membranes Resulting from Coupling of Membrane Asymmetry, Curvature, and Lipid Sorting(Weinheim : Wiley-VCH, 2021) Steinkühler, Jan; Fonda, Piermarco; Bhatia, Tripta; Zhao, Ziliang; Leomil, Fernanda S. C.; Lipowsky, Reinhard; Dimova, RumianaBiological cells are contained by a fluid lipid bilayer (plasma membrane, PM) that allows for large deformations, often exceeding 50% of the apparent initial PM area. Isolated lipids self-organize into membranes, but are prone to rupture at small (<2–4%) area strains, which limits progress for synthetic reconstitution of cellular features. Here, it is shown that by preserving PM structure and composition during isolation from cells, vesicles with cell-like elasticity can be obtained. It is found that these plasma membrane vesicles store significant area in the form of nanotubes in their lumen. These act as lipid reservoirs and are recruited by mechanical tension applied to the outer vesicle membrane. Both in experiment and theory, it is shown that a “superelastic” response emerges from the interplay of lipid domains and membrane curvature. This finding allows for bottom-up engineering of synthetic biomaterials that appear one magnitude softer and with threefold larger deformability than conventional lipid vesicles. These results open a path toward designing superelastic synthetic cells possessing the inherent mechanics of biological cells.