Date of Award
12-2011
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Legacy Department
Chemistry
Committee Chair/Advisor
McNeill, Jason
Committee Member
Stuart , Steven
Committee Member
Kholodenko , Arkady
Committee Member
Dominy , Brian
Abstract
Energy transport in conjugated polymers is the combination of energy transfer and exciton diffusion. There is considerable ongoing research in this field, converging to develop better organic photovoltaics, polymer light emitting diodes (PLEDs) and organic solar cells, to name a few. One way these phenomena can be explored is by doing solution dependent studies on conjugated polymer nanoparticles. With experiments on CP dots in an aqueous solution and the addition of a water miscible organic solvent in varying concentrations, dynamics occurring in the folding process can be better understood, and also exciton and fluorescence quenching properties can be extracted as a function of nanoparticle collapse. Steady state and time resolved fluorescence measurements were taken for two types of CP dots in bulk solution under varying solvent environments, including quantum yield, photobleaching and reversible photobleaching. The time-domain technique of time-correlated single photon counting (TCSPC) was used to determine excited state lifetimes and fluorescent decay traces. Simulating the TCSPC data provides insight on the relative number of quenchers that are observed by the polymer in each environment. In addition, single molecule fluorescence spectroscopy measurements were done on CP dots under varying solvent vapor atmospheres. Using the phenomenon of energy transfer, we have proven that doping the singlet oxygen photosensitizer tetraphenylporphyrin (TPP) into our conjugated polymer nanoparticles acts as an efficient and powerful photosensitizer for photodynamic therapy. The nanoparticles exhibit highly efficient collection of excitation light due to the large excitation cross-section of the polymer. A quantum efficiency of 0.5 was determined. Extraordinarily large cross-sections for two-photon absorption were found which is promising for near infrared multiphoton photodynamic therapy, and gel electrophoresis of DNA after irradiation in the presence of CP dots indicated extensive purine base and backbone DNA damage.
Recommended Citation
Grimland, Jennifer, "SINGLE PARTICLE AND ENSEMBLE SPECTROSCOPY OF CONJUGATED POLYMER NANOPARTICLES AND THEIR DEVELOPMENT FOR PHOTODYNAMIC THERAPY" (2011). All Dissertations. 867.
https://open.clemson.edu/all_dissertations/867