紫膜(purple membrane, PM)為Halobacterium salinarum細胞膜的一部份，其內部的細菌視紫質(bacteriorhodopsin, BR)受光激發後可產生光電流響應。本研究結合液滴塗覆法及微流體塗覆二種方式進行PM於基材上的塗覆，探討不同塗覆方法及不同架橋對PM晶片製備的影響，並以AFM及微分光電流響應進行分析。所使用架橋包括活化avidin (activated avidin, OA)、氧化石墨烯(graphene oxide, GO)及GO-OA複合物。其中以GO作為架橋製備PM晶片時，所得到光電流響應在所有PM晶片製程中為最小的光電流響應。對於OA架橋，以微流塗覆OA後再分別以液滴塗覆法或微流塗覆b-PM後，所得到光電流響應分別約為1000 nA/cm2及600 nA/cm2。對於GO-OA複合架橋，以微流體塗覆GO-OA複合物後再分別以液滴塗覆法及微流體塗覆b-PM，所得到光電流響應分別約為1267 nA/cm2及1017 nA/cm2。而以液滴塗覆法分別先塗覆OA及GO-OA複合物後，再以液滴塗覆法塗覆b-PM，所得到光電流響應分別約為1462 nA/cm2及1511 nA/cm2，表示GO加入OA架橋中有助於b-PM的貼附，以及雙重液滴塗覆法的製程具有較好b-PM塗覆效果。另外，探討剪應力流場對使用雙重液滴塗覆法製程及以OA或GO-OA複合物為架橋所製備PM晶片的影響。對於OA架橋，以高流速清洗後可達到接近單層b-PM貼附；而以GO-OA複合物為架橋所製備的PM晶片經由低流速清洗後，即可達到幾乎完全覆蓋填滿、單一方向且單層貼附的b-PM，此單一方向為ITO/EC-CP定向，單層b-PM的覆蓋率可由21 %增加至91 %。以微分光電流響應分析，可得知ITO/EC-CP定向之單層b-PM所貢獻的光電流響應約為75 %，而另外25 %的光電流響應則是由疊層b-PM所提供。此外，此單層、高覆蓋率及單一方向貼附之PM晶片具有良好的重複檢測穩定度，經由30次微分光電流響應檢測後其光電流響應仍然維持不變，並可進行後續的biotin-E. coli抗體固定化及E. coli的微流體檢測。

Purple membrane (PM) is a cellular component of Halobacterium salinarum containing bacteriorhodopsin, which generates photoelectric responses after being excited by light. In this study, either drop-casting or microfluidics-based fabrication was employed to prepare PM chips with different linkers to investigate the effect of fabrication methods and linkers on the chip characteristics. Both AFM analysis and the measurement of differential photocurrents generated by PM chips were conducted to evaluate the fabrications. Three different linkers were investigated, including activated avidin (OA), graphene oxide (GO) and GO-OA complex. The PM chips fabricated with GO as the linker yielded the lowest photocurrent. On the OA linker fabricated on substrates with microfluidics, the subsequent coating of biotinylated PM (b-PM) by drop-casting and with microfluidics resulted in the production of 1000 nA/cm2 and 600 nA/cm2 photocurrent densities, respectively. On the other hand, the coating of b-PM on the microfluidics-fabricated GO-OA linker by drop-casting and with microfluidics yielded 12670 nA/cm2 and 1017 nA/cm2 photocurrent densities, respectively. For double drop-casting processes, 1462 nA/cm2 and 1511 nA/cm2 were achieved by drop-casting b-PM on drop-casted OA and GO-OA linkers, respectively. These results suggest the addition of GO in linkers facilitated b-PM coating and the processes with double drop-casting resulted in the best b-PM fabrication. Furthermore, we investigated the effect of shear flow in microfluidics on the PM chips prepared by drop-casting both the linker and b-PM. For the OA linker, a near monolayer of b-PM was achieved at a high flow rate. However, a slow shear flow was sufficiently enough for the GO-OA linker to produce a monolayer of b-PM with full coverage and uniform orientation (ITO/EC-CP) on substrates. The monolayer coverage of b-PM on substrates was increased from 21% to 91% with the slow shear flow over the PM chips prepared with double drop-casting and the GO-OA linker. In addition, the photocurrent analysis indicated that the as-prepared PM chip maintained its photoelectric activity after 30 repetitive measurements and concluded that 75% and 25% of the chip photocurrent were attributed to the monolayer and stacks of PM, respectively. The use of the as-prepared PM chip to immobilize anti-Escherichia coli antibodies and to subsequently detect E. coli was also demonstrated.

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