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Photoctive Nanofiber Membranes for Oxygen Sensing
Ludačka, Pavel ; Mosinger, Jiří (advisor) ; Lang, Kamil (referee)
In this work, luminescent oxygen sensors based on the quenching of porphyrin sensor molecules encapsulated in a nanofibrous polymer matrix prepared by electrospinning were prepared and studied. The prepared sensors were characterized using electron microscopy, absorption and emission spectra, including time-resolved emission spectra. The sensitivity of the sensors was optimized in different polymer matrices, concentrations of porphyrin sensor molecules, and the thickness of the nanofibrous sensor layer. Furthermore, the photogeneration of singlet oxygen and the resulting antibacterial properties of the sensor nanofiber membrane were demonstrated. Key words Photoactive, nanofiber, oxygen, singlet oxygen, optical sensor
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Photoactive chlorophyll nanoparticles
Ludačka, Pavel ; Mosinger, Jiří (advisor) ; Lang, Kamil (referee)
Photoactive sulfonated and non-sulfonated polystyrene nanoparticles (NPs) with encapsulated THF extract from spinach (Spinacia oleracea) were prepared. The preparation of NPs is based on a simple nanoprecipitation method that uses the same solvent (THF) to dissolve the sulfonated or non-sulfonated polystyrene nanofiber membrane and for the extraction itself. Based on spectral and HPLC analysis, it was found that the THF extract and NPs contain chlorophyll a, chlorophyll b, β-carotene and lutein. Time-resolved spectroscopy shows that the extract is a potent source of singlet oxygen O2(1 g) thank to the photosensitizer chlorophyll. The photogeneration of O2(1 g) is partially suppressed by the carotenoids in the extract, which quench O2(1 g). To reduce the quenching effect of carotenoids, it is possible to use dilute extract or pre-irradiated samples with visible light because of carotenoids rapid breakup. A strong photooxidative and antibacterial effect of NPs prepared from an extract generating O2(1 g) was demonstrated on chemical substrates and Escherichia coli. The photoactivity of NPs is initiated by visible light. Key words Chlorophyll, photosensitizer, nanoparticle, singlet oxygen
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