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Gold nano systems for the detection of molecules using surface-enhanced Raman scattering (SERS)
Benešová, Markéta ; Bernatová,, Silvie (referee) ; Skoumalová, Petra (advisor)
This diploma thesis was focused on the production and use of gold nanosystems to enhance Raman scattering. Metal nanoparticles, when interacting with electromagnetic radiation, form so-called localized plasmons, which can enhance Raman scattering. SERS (surface-enhanced Raman scattering) is a non-destructive analytical technique used in this work to measure the concentration and chemical changes in the rhodamine B molecule. Rhodamine B was subjected to photocatalytic degradation using two types of photocatalysts before measurement: TiO2-(H) and TiO2-(H)-Ag. The quantitative dependence of rhodamine B photodegradation on the presence of photocatalysts in a given period time was sought using photodegradation processes. The results of measurements using the SERS method were compared with the results obtained by UV-VIS spectroscopy. From the measured data, it was found that the photocatalysts significantly accelerate the photodegradation processes, because the Raman signal of rhodamine B decreased, while the signal decrease was most pronounced for the catalyst with added TiO2-(H)-Ag, less prominent but still statistically significant signal decrease was observed for the TiO2-(H) catalyst. In the control sample without the addition of photocatalyst, no decrease in signal was observed. In the next phase of the thesis, a sandwich immunoassay was designed that uses SERS to detect E. coli bacteria or other specific microorganisms in the sample. The first component of the sandwich immunoassay is gold nanoparticles, which carry a so-called Raman reporter, which has a clear Raman response in the spectrum, and gold nanoparticles amplify this signal, and antibodies, thanks to which the particles specifically bind to the microorganism. Another component is either gold layered slides or magnetic nanoparticles, which are modified with antibodies and serve to immobilize microorganisms. This system can be a fast and very accurate way to identify a given microorganism in a sample.
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Measurement of resonant properties of plasmonic nanostructures in transmission and reflection mode of far-field spectroscopy
Klement, Robert ; Brzobohatý, Oto (referee) ; Šikola, Tomáš (advisor)
Far-field optical spectroscopy allows for measurement of plasmonic resonances on metallic nanostructures of various shapes and sizes when illuminated by continuous light. Employing dark-field microscopy makes it possible to measure scattering on a localised plasmon excited on a single, isolated nanostructure. For the purpose of these measurements an apparatus based on commercial dual microscope system Nanonics has been put together. Experiments carried out during work on this thesis have shown a great sensitivity of the apparatus in its present form, allowing to measure a plasmonic resonance of a single nanoparticle. Proposed improvements of the apparatus should lead to even greater sensitivity and precision of measurements in the near future.
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Gold nano systems for the detection of molecules using surface-enhanced Raman scattering (SERS)
Benešová, Markéta ; Bernatová,, Silvie (referee) ; Skoumalová, Petra (advisor)
This diploma thesis was focused on the production and use of gold nanosystems to enhance Raman scattering. Metal nanoparticles, when interacting with electromagnetic radiation, form so-called localized plasmons, which can enhance Raman scattering. SERS (surface-enhanced Raman scattering) is a non-destructive analytical technique used in this work to measure the concentration and chemical changes in the rhodamine B molecule. Rhodamine B was subjected to photocatalytic degradation using two types of photocatalysts before measurement: TiO2-(H) and TiO2-(H)-Ag. The quantitative dependence of rhodamine B photodegradation on the presence of photocatalysts in a given period time was sought using photodegradation processes. The results of measurements using the SERS method were compared with the results obtained by UV-VIS spectroscopy. From the measured data, it was found that the photocatalysts significantly accelerate the photodegradation processes, because the Raman signal of rhodamine B decreased, while the signal decrease was most pronounced for the catalyst with added TiO2-(H)-Ag, less prominent but still statistically significant signal decrease was observed for the TiO2-(H) catalyst. In the control sample without the addition of photocatalyst, no decrease in signal was observed. In the next phase of the thesis, a sandwich immunoassay was designed that uses SERS to detect E. coli bacteria or other specific microorganisms in the sample. The first component of the sandwich immunoassay is gold nanoparticles, which carry a so-called Raman reporter, which has a clear Raman response in the spectrum, and gold nanoparticles amplify this signal, and antibodies, thanks to which the particles specifically bind to the microorganism. Another component is either gold layered slides or magnetic nanoparticles, which are modified with antibodies and serve to immobilize microorganisms. This system can be a fast and very accurate way to identify a given microorganism in a sample.
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Measurement of resonant properties of plasmonic nanostructures in transmission and reflection mode of far-field spectroscopy
Klement, Robert ; Brzobohatý, Oto (referee) ; Šikola, Tomáš (advisor)
Far-field optical spectroscopy allows for measurement of plasmonic resonances on metallic nanostructures of various shapes and sizes when illuminated by continuous light. Employing dark-field microscopy makes it possible to measure scattering on a localised plasmon excited on a single, isolated nanostructure. For the purpose of these measurements an apparatus based on commercial dual microscope system Nanonics has been put together. Experiments carried out during work on this thesis have shown a great sensitivity of the apparatus in its present form, allowing to measure a plasmonic resonance of a single nanoparticle. Proposed improvements of the apparatus should lead to even greater sensitivity and precision of measurements in the near future.
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