Filters

2020 - 20212

More filters

2021 - 20222
Reset filters

Settings

Author: Cialla-May, Dana × Author: Popp, Jürgen × Author: Weber, Karina × End date: 2024 × Start date: 2020 × WGL Institute: IPHT ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Raman Signal Enhancement Tunable by Gold-Covered Porous Silicon Films with Different Morphology
    (Basel : MDPI, 2020) Agafilushkina, Svetlana N.; Žukovskaja, Olga; Dyakov, Sergey A.; Weber, Karina; Sivakov, Vladimir; Popp, Jürgen; Cialla-May, Dana; Osminkina, Liubov A.
    The ease of fabrication, large surface area, tunable pore size and morphology as well surface modification capabilities of a porous silicon (PSi) layer make it widely used for sensoric applications. The pore size of a PSi layer can be an important parameter when used as a matrix for creating surface-enhanced Raman scattering (SERS) surfaces. Here, we evaluated the SERS activity of PSi with pores ranging in size from meso to macro, the surface of which was coated with gold nanoparticles (Au NPs). We found that different pore diameters in the PSi layers provide different morphology of the gold coating, from an almost monolayer to 50 nm distance between nanoparticles. Methylene blue (MB) and 4-mercaptopyridine (4-MPy) were used to describe the SERS activity of obtained Au/PSi surfaces. The best Raman signal enhancement was shown when the internal diameter of torus-shaped Au NPs is around 35 nm. To understand the role of plasmonic resonances in the observed SERS spectrum, we performed electromagnetic simulations of Raman scattering intensity as a function of the internal diameter. The results of these simulations are consistent with the obtained experimental data
  • Thumbnail Image
    Item
    Surface enhanced Raman spectroscopy-based evaluation of the membrane protein composition of the organohalide-respiring Sulfurospirillum multivorans
    (Chichester [u.a.] : Wiley, 2021) Cialla-May, Dana; Gadkari, Jennifer; Winterfeld, Andreea; Hübner, Uwe; Weber, Karina; Diekert, Gabriele; Schubert, Torsten; Goris, Tobias; Popp, Jürgen
    Bacteria often employ different respiratory chains that comprise membrane proteins equipped with various cofactors. Monitoring the protein inventory that is present in the cells under a given cultivation condition is often difficult and time-consuming. One example of a metabolically versatile bacterium is the microaerophilic organohalide-respiring Sulfurospirillum multivorans. Here, we used surface enhanced Raman spectroscopy (SERS) to quickly identify the cofactors involved in the respiration of S. multivorans. We cultured the organism with either tetrachloroethene (perchloroethylene, PCE), fumarate, nitrate, or oxygen as electron acceptors. Because the corresponding terminal reductases of the four different respiratory chains harbor different cofactors, specific fingerprint signals in SERS were expected. Silver nanostructures fabricated by means of electron beam lithography were coated with the membrane fractions extracted from the four S. multivorans cultivations, and SERS spectra were recorded. In the case of S. multivorans cultivated with PCE, the recorded SERS spectra were dominated by Raman peaks specific for Vitamin B12. This is attributed to the high abundance of the PCE reductive dehalogenase (PceA), the key enzyme in PCE respiration. After cultivation with oxygen, fumarate, or nitrate, no Raman spectral features of B12 were found. © 2020 The Authors. Journal of Raman Spectroscopy published by John Wiley & Sons Ltd