Photoinduced Synthesis of Fluorescent Gold Nanoclusters in Polymer Films
Hänninen, Jussi (2021)
Hänninen, Jussi
2021
Master's Programme in Science and Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2021-02-22
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202102192158
https://urn.fi/URN:NBN:fi:tuni-202102192158
Tiivistelmä
Nanoclusters (NCs) are a class of fluorescent material that consists of a few to a few hundreds of atoms. NCs have a diameter smaller than 2 nm, which is comparable to the Fermi wavelength of electrons. In this size, continuous energy levels of material become discrete, and the material exhibits fluorescence properties. Synthesis of NCs is difficult because they tend to aggregate to larger nonfluorescent nanoparticles. Thus, protecting agents are required to prevent aggregation. These agents include thiol compounds, proteins, glass, and polymers.
This work aims to photo-synthesize gold NCs (AuNCs) in two widely used polymers, bisphenol A polycarbonate (BPA-PC) and biodegradable polyvinyl alcohol (PVA). Synthesis routes were developed for polymer films containing photoinitiator and gold salt of required concentrations and thicknesses. Next, films were exposed to a low-power LED with a wavelength of 365 nm (for BPA-PC) and 405 nm (for PVA), leading to the formation of bright fluorescent AuNCs.
The growth of fluorescence was studied using a custom-made fluorescence microscope. Fluorescence spectroscopy showed broad emission spectra peaked at 486 nm (excited with 386 nm) for BPA-PC and 530 nm (excited with 490 nm) for PVA. The chemical properties of the films were studied with differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The thermal properties of films changed after AuNCs were synthesized in the film. FTIR measurements on as formed AuNCs display small changes in the chemical structures of the polymers. All the results were analyzed and compared to previous studies found in the literature.
In this work, fluorescent AuNCs were successfully synthesized in BPA-PC and PVA films. The previous report of AuNCs synthesis in BPA-PC film with this method has not been published. This method potentially allows the use of AuNCs in different applications example authenticity marking, imaging, and medicine. The main problem is still how to produce polymer film containing photoinitiator and gold salt on an industrial scale.
This work aims to photo-synthesize gold NCs (AuNCs) in two widely used polymers, bisphenol A polycarbonate (BPA-PC) and biodegradable polyvinyl alcohol (PVA). Synthesis routes were developed for polymer films containing photoinitiator and gold salt of required concentrations and thicknesses. Next, films were exposed to a low-power LED with a wavelength of 365 nm (for BPA-PC) and 405 nm (for PVA), leading to the formation of bright fluorescent AuNCs.
The growth of fluorescence was studied using a custom-made fluorescence microscope. Fluorescence spectroscopy showed broad emission spectra peaked at 486 nm (excited with 386 nm) for BPA-PC and 530 nm (excited with 490 nm) for PVA. The chemical properties of the films were studied with differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The thermal properties of films changed after AuNCs were synthesized in the film. FTIR measurements on as formed AuNCs display small changes in the chemical structures of the polymers. All the results were analyzed and compared to previous studies found in the literature.
In this work, fluorescent AuNCs were successfully synthesized in BPA-PC and PVA films. The previous report of AuNCs synthesis in BPA-PC film with this method has not been published. This method potentially allows the use of AuNCs in different applications example authenticity marking, imaging, and medicine. The main problem is still how to produce polymer film containing photoinitiator and gold salt on an industrial scale.