Suchergebnisse

A new soft ionization device for mass spectrometry is presented using the flexible microtube plasma under controlled atmospheric conditions. The controlled atmosphere flexible microtube plasma consists of the plasma source itself connected to a gas chromatograph and a mass spectrometer using a borosilicate glass cross piece. Controlled atmosphere, for example, nitrogen and/or an oxygen mixture, is introduced to the system to create a clean ionization environment. Reproducibility issues are discussed, and solutions are presented manipulating the gas flow in the cross piece. A proof of concept is shown using a ketone mixture introduced to the mass spectrometer to optimize atmospheric conditions. Furthermore, application of the presented device for the sensitive and nonfragmenting ionization of volatile organic biomarkers relevant for cancer is carried out. Sample treatment for human saliva is described, and relevant candidate biomarkers are measured in the saliva matrix, showing a very good ionization efficiency and neglectable matrix effects with limits of detection below 80 ppt. ; This project received funding from the European Union's Horizon 2020 research and innovation program under grant agreement 810686 and under the Marie Sklodowska-Curie grant agreement number 840743.

Reactive oxygen and nitrogen species (RONS) play a central role in the immune system and on disease progression and therefore are important in the therapeutic abilities of the atmospheric pressure plasma jet (APPJ) [1]. In addition to RONS, the APPJ induces an electric field (IEF) on the biological cells. It can be inferred that it is the combination of IEF and RONS and not just RONS that gives the APPJ its unique therapeutic abilities, such as selectively treating cancer [2]. In the case of helium APPJ it was found that the addition of oxygen impurities allowed for more effective treatment of cancer cells [3]. Putting it all together, the hypothesis is that the addition of oxygen causes higher IEF on cancerous cells causing electroporation and the introduction of RONS in the cells causing apoptosis. In this abstract a two-dimensional axi-symmetric model is developed [4] for the description of a capillary helium plasma jet with and without the presence of oxygen admixtures and their interaction with a dielectric surface placed normal to the jet axis. The results in Figure 1 show that He/O2 plasma jets generates higher IEF in comparison to the pure He plasma jet. Furthermore, the peak of the IEF on the dielectric surface is on the axis of symmetry for He/O2 plasma jets and off the axis of symmetry for pure He plasma jet. This project has received funding from the European Union's Horizon 2020 research and innovation programme under agreement No. 810686. References [1] D. B. Graves, Phys. Plasmas, 21, 080901 (2014) [2] J. Van der Paal, C. Verheyen, E. C. Neyts and A. Bogaerts, Sci. Rep., 7, 39526 (2017) [3] S. J. Kim, T. H. Chung, S. H. Bae and S. H. Leem, Appl. Phys. Lett., 97, 023702 (2010) [4] C. Lazarou, C. Anastassiou, I. Topala, A. S. Chiper, I. Mihaila, V. Pohoata and G. E. Georghiou, Plasma Sources Sci. Technol., 27, 105007 (2018) ; International Workshop on Plasma for Cancer Treatment (IWPCT 2019), April 1-3, 2019 Antwerp, Belgium