Development of a multi-wavelength fluorescence lifetime system for monitoring photosynthesis activities

• Main Authors: Lan, Pei-Xuan, 藍培軒
• Other Authors: Chen, Yi-Chun
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/esanan

碩士 === 國立交通大學 === 影像與生醫光電研究所 === 106 === Green algae is one of the most important source of biomass and biofuel. It has been known that culture condition, especially illumination light, decides photosynthesis efficiency hence the yield of biomass in green algae. Conventional instruments to monitor photosynthesis activities measure Chlorophyll a fluorescence intensity. However, as a very complex system, it is difficult to quantitatively identify photosynthesis reactions based on Chlorophyll a fluorescence intensity solely. In this thesis, I developed a nanosecond-resolved multi-wavelength fluorescence lifetime system, and applied this fluorescence lifetime system to study photosynthesis activities of green algae in vivo. In my lifetime system, the wavelength of illumination light excites different light-absorbing pigments in photosynthesis, therefore provides information on their corresponding pathways. Then, the state of each pathway can be evaluated by fluorescence lifetime in combination with fluorescence intensity. In my study, a multi-die light-emitting diode (LED) was used as the light source. The LED was modulated at radio frequency by signals from a field-programmable gate array (FPGA). I designed a switching circuit to address individual die on the multi-wavelength multi-die LED. This system was applied to measure Chlorophyll a signals of green algae in vivo. In the experiments, I changed either the wavelength or the intensity of activation light that excited Chlorophyll a, and I observed different fluorescence lifetime components and different dynamic decay curve of fluorescence intensity under different light condition. Related non-photochemical quenching pathways was discussed in this thesis.