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Title: | 新型光感物質BMVC之特性分析及其光動力抑菌作用 Characteristics of a novel photosensitizer BMVC and its application on microbial photoinactivation |
Authors: | Min-Tzu Lo 羅敏慈 |
Advisor: | 黃慶璨 |
Keyword: | BMVC,G+C含量,光動力治療, BMVC,G+C content,photodynamic therapy, |
Publication Year : | 2008 |
Degree: | 碩士 |
Abstract: | 光動力療法 (photodynamic therapy) 係利用光感物質 (photosensitizer) 經特定波長光源激發後所產生之單態氧 (singlet oxygen) 與自由基造成菌體傷害;臨床上已被大量應用在毒殺癌細胞,作為微生物防治方亦具有顯著效果。本研究將探討本身為螢光探針的BMVC (3, 6-bis(1-methyl- 4-vinylpyridinium)carbazole diiodide),經過特定波長光源激發後的光動力作用之抑菌效果;及其作為光感物質的特性分析。結果顯示,BMVC 引起之光動力作用可抑制革蘭氏陽性菌 Staphylococcus aureus 與 Micrococcus luteus,且殺菌效果隨光感物質濃度與照光劑量增加而增強,作用於革蘭氏陰性菌Escherichia coli則需提高光感物質濃度與照光劑量達 10 倍以上才具有毒殺效果,即 BMVC 可作為光感物質進行光動力抑菌作用。當BMVC與不同G+C含量之 DNA 結合時,吸收與螢光光譜會有差異,除螢光強度增強,最大放射波長 (emission wavelength) 會出現紅移 (red-shift) 現象,故此螢光探針亦可發展出光動力診斷 (photodynamic diagnosis) 的用途。由蒲朗克定律 (planck law) 可知光波波長與能量的關係;故本研究以光化學角度探討光譜差異性與光動力抑菌作用的關係。由於BMVC與AT的結合力比GC好,分子結構穩定的情況下將減少電子發生內部轉換的機會,即相同的電子濃度被激發,能有越多電子躍遷至激發單重態 (excited singlet state),接著釋放能量發散螢光回到基態;亦可經由系統間跨越 (intersystem crossing) 至激發三重態 (excited triplet state) 後,再透過能量轉移產生單態氧。實驗結果亦證實,BMVC 引起之光動力作用對於毒殺低G+C含量的 Staphylococcus aureus 的效果,比高G+C含量的 Micrococcus luteus 更為顯著。本研究之 BMVC 除本身所具有的螢光標定性,可區分不同結構之 DNA,亦可作為光感物質發展光動力治療,應用於微生物防治更具潛力。 Photodynamic therapy (PDT) utilizes a nontoxic photosensitizer upon irradiation with an appropriate wavelength in the presence of oxygen, then generating cytotoxic reactive oxygen species to inactivate cancer cells as well as microorganisms. The goal of this study is to investigate the role of a novel fluorescence probe BMVC (3, 6-bis(1-methyl-4- vinylpyridium)carbazole diiodide) in the photodynamic inactivation against bacteria. BMVC showed more significant phototoxicity against Gram positive Staphylococcus aureus and Micrococcus luteus than Gram negative Escherichia coli. The fluorescence intensity of BMVC was much higher when interacting with DNA, and increased with increasing of AT to GC ratio. In addition, the emission maximum appeared red-shift in the presence of GC. The BMVC-mediated photodynamic inactivation showed more significant efficacy against low G+C content Staphylococcus aureus than high G+C content Micrococcus luteus. The difference can be attributed to the stable structures of BMVC-AT complex, resulting in better efficacy against low G+C content Gram positive bacteria. The quenching by NaN3, a specific quencher to singlet oxygen, did not complete neutralize the BMVC-mediated photodynamic inactivation against Staphylococcus aureus and Micrococcus luteus, indicating that the photodynamic action of BMVC mixed with the formation of both free radicals and singlet oxygen. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/41034 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 微生物學科所 |
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