@article{BlockMayWetzeletal.2023,
  author    = {Block, Franziska and May, Alexander and Wetzel, Katharina and Adels, Klaudia and Elbers, Gereon and Schulze, Margit and Monakhova, Yulia},
  title     = {What is the best spectroscopic method for simultaneous analysis of organic acids and (poly)saccharides in biological matrices: Example of Aloe vera extracts?},
  series = {Talanta Open},
  volume    = {7},
  journal   = {Talanta Open},
  number    = {Art. No. 100220},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {2666-8319},
  doi       = {10.1016/j.talo.2023.100220},
  pages     = {1 -- 9},
  year      = {2023},
  abstract  = {Several species of (poly)saccharides and organic acids can be found often simultaneously in various biological matrices, e.g., fruits, plant materials, and biological fluids. The analysis of such matrices sometimes represents a challenging task. Using Aloe vera (A. vera) plant materials as an example, the performance of several spectro-scopic methods (80 MHz benchtop NMR, NIR, ATR-FTIR and UV-vis) for the simultaneous analysis of quality parameters of this plant material was compared. The determined parameters include (poly)saccharides such as aloverose, fructose and glucose as well as organic acids (malic, lactic, citric, isocitric, acetic, fumaric, benzoic and sorbic acids). 500 MHz NMR and high-performance liquid chromatography (HPLC) were used as the reference methods. UV-vis data can be used only for identification of added preservatives (benzoic and sorbic acids) and drying agent (maltodextrin) and semiquantitative analysis of malic acid. NIR and MIR spectroscopies combined with multivariate regression can deliver more informative overview of A. vera extracts being able to additionally quantify glucose, aloverose, citric, isocitric, malic, lactic acids and fructose. Low-field NMR measurements can be used for the quantification of aloverose, glucose, malic, lactic, acetic, and benzoic acids. The benchtop NMR method was successfully validated in terms of robustness, stability, precision, reproducibility and limit of detection (LOD) and quantification (LOQ), respectively. All spectroscopic techniques are useful for the screening of (poly)saccharides and organic acids in plant extracts and should be applied according to its availability as well as information and confidence required for the specific analytical goal. Benchtop NMR spectroscopy seems to be the most feasible solution for quality control of A. vera products.},
  language  = {en}
}
@article{OezsoyluAliaziziWagneretal.2024,
  author    = {{\"O}zsoylu, Dua and Aliazizi, Fereshteh and Wagner, Patrick and Sch{\"o}ning, Michael Josef},
  title     = {Template bacteria-free fabrication of surface imprinted polymer-based biosensor for E. coli detection using photolithographic mimics: Hacking bacterial adhesion},
  series = {Biosensors and Bioelectronics},
  volume    = {261},
  journal   = {Biosensors and Bioelectronics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1873-4235 (eISSN)},
  doi       = {10.1016/j.bios.2024.116491},
  pages     = {11 Seiten},
  year      = {2024},
  abstract  = {As one class of molecular imprinted polymers (MIPs), surface imprinted polymer (SIP)-based biosensors show great potential in direct whole-bacteria detection. Micro-contact imprinting, that involves stamping the template bacteria immobilized on a substrate into a pre-polymerized polymer matrix, is the most straightforward and prominent method to obtain SIP-based biosensors. However, the major drawbacks of the method arise from the requirement for fresh template bacteria and often non-reproducible bacteria distribution on the stamp substrate. Herein, we developed a positive master stamp containing photolithographic mimics of the template bacteria (E. coli) enabling reproducible fabrication of biomimetic SIP-based biosensors without the need for the "real" bacteria cells. By using atomic force and scanning electron microscopy imaging techniques, respectively, the E. coli-capturing ability of the SIP samples was tested, and compared with non-imprinted polymer (NIP)-based samples and control SIP samples, in which the cavity geometry does not match with E. coli cells. It was revealed that the presence of the biomimetic E. coli imprints with a specifically designed geometry increases the sensor E. coli-capturing ability by an "imprinting factor" of about 3. These findings show the importance of geometry-guided physical recognition in bacterial detection using SIP-based biosensors. In addition, this imprinting strategy was employed to interdigitated electrodes and QCM (quartz crystal microbalance) chips. E. coli detection performance of the sensors was demonstrated with electrochemical impedance spectroscopy (EIS) and QCM measurements with dissipation monitoring technique (QCM-D).},
  language  = {en}
}
@article{AdelsMonakhova2024,
  author    = {Adels, Klaudia and Monakhova, Yulia},
  title     = {Low-field NMR spectroscopic study of e-cigarettes: Is determination of only nicotine and organic carrier solvents possible?},
  series = {Microchemical Journal},
  volume    = {203},
  journal   = {Microchemical Journal},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1095-9149},
  doi       = {10.1016/j.microc.2024.110859},
  pages     = {9 Seiten},
  year      = {2024},
  abstract  = {Electronic cigarettes (e-cigarettes) have become popular worldwide with the market growing exponentially in some countries. The absence of product standards and safety regulations requires urgent development of analytical methodologies for the holistic control of the growing diversity of such products. An approach based on low-field nuclear magnetic resonance (LF-NMR) at 80 MHz is presented for the simultaneous determination of key parameters: carrier solvents (vegetable glycerine (VG), propylene glycol (PG) and water), total nicotine as well as free-base nicotine fraction. Moreover, qualitative and quantitative determination of fourteen weak organic acids deliberately added to enhance sensory characteristics of e-cigarettes was possible. In most cases these parameters can be rapidly and conveniently determined without using any sample manipulation such as dilution, extraction or derivatization steps. The method was applied for 37 authentic e-cigarettes samples. In particular, eight different organic acids with the content up to 56 mg/mL were detected. Due to its simplicity, the method can be used in routine regulatory control as well as to study release behaviour of nicotine and other e-cigarettes constituents in different products.},
  language  = {en}
}