Halobacterium salinarum的紫膜（purple membrane，PM）是由細菌視紫質（bacteriorhodopsin，BR）和脂質所構成。由於BR受光激發後會產生跨PM膜的質子梯度，因此可利用此特性產生光電流；此外因為PM穩定性極佳，可於基材上平整貼附，所以可作為檢驗平台。為了進一步了解BR的光電與貼附特性，將PM以生物親和作用塗覆於導電ITO玻璃上，製作生物晶片；其間以循環伏安法（cyclic voltammetry，CV）來探討晶片的逐層塗覆與PM貼覆，並利用和奈米金或量子點（quantum dot）的結合分別以光散射及螢光分析來檢測PM的貼附與修飾，或甚至調整其光電響應。
藉由CV的分析，可發現逐層塗覆會使晶片的CV圖逐漸扭曲變形，氧化和還原峰降低且電阻值上升，證實PM塗覆成功。此外，光散射的分析顯示僅有可和奈米金結合的PM晶片具有光散射訊號，且再進一步以銀染強化可使其光散射訊號增強且更均勻，此可作為未來快速檢驗PM塗覆的平台。之後，量測塗覆上奈米金之PM晶片之光電流，可發現奈米金會對PM之光電響應產生影響，未來希望可用此特性將PM做為一偵測平台。再者同時使用可發射出綠色螢光的量子點及藍光照射，可使BR在被光激發後很快地由M態回至B態，造成PM膜內受光激發所產生的質子梯度不會逸散至電解液中，而得以取得穩定的連續光電流響應，此和以往PM的脈衝式光電流訊號截然不同，可應用於光能電池的開發，而之後也會繼續探討量子點、PM在不同pH值下之交互作用關係。

Purple membrane (PM) of Halobacterium salinarum is constituted of bacteriorhodopsin (BR) and lipid. Upon photoexcitation by green light, BR produces a proton gradient across PM, which can be applied to generate photocurrents. Furthermore, PM is very stable and can be two-dimensionally attached to substrates so it can be used as a sensing platform. To elucidate the photocurrent and attachment properties of PM, monolayer PM photoelectric biochips were prepared by avidin/biotin bioaffinity immobilization of PM onto ITO glass and analyzed for the layer-by-layer coating by cyclic voltammetry (CV) as well as by light-scattering analysis through nanogolds. In addition, fluorescence analyses were performed to confirm the biotinylation of PM. Finally, nanogolds and quantum dots (QDs) were each applied to regulate the photocurrent of PM chips.
The CV analysis results confirmed the successful coating of PM with the evidence of gradual distortion of the scanned spectra arising from the reduction of both oxidation and reduction peaks, which were caused by increasing resistance during the layer-by-layer coating. In addition, light scattering was observed only on PM chips attached with nanogolds and both the intensity and uniformity of the scattering signals were further augmented by silver enhancement. Therefore, light scattering can be employed as a rapid test platform to check the PM coating. Moreover, the photocurrents of PM chips changed significantly when nanogolds were attached on, suggesting that a PM-based sensing chip could be developed in the near future.
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Finally, the blue-light illumination of PM chips attached with green fluorescent QDs yielded stable continuous photocurrents, which were utterly different from the usual pulse signals of PM chips, implying the retainment of the pumped protons within the membrane possibly due to the acceleration of transforming the photoexcited BR from the M state back to the ground B state by the green light. The finding suggests the potential of BR for solar cell development.

余安棣，“製備具高度方向性Bacteriorhodopsin生物光電晶片”，國立台灣科技大
學化學工程研究所碩士論文 (2009)
陳逸航，“定向性細菌視紫質晶片之光電與二倍頻響應探討”，國立台灣科技大
學化學工程研究所碩士論文 (2010)
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