開發高靈敏度之液晶感測器以應用於癌症生物標記CA-125之無標記免疫偵測

Liquid-Crystal-Based Biosensor Having Ultrahigh Sensitivity for Label-Free Immunodetection of the Cancer Biomarker CA-125

蘇慧汶(Hui-Wen Su)

指導教授 ： 李偉 ； 李孟娟

國立交通大學/光電學院/影像與生醫光電研究所/碩士(2014年)

https://doi.org/10.6842/NCTU.2014.00201

摘要

現行之傳統免疫檢測皆須使用螢光或酵素標記之抗體進行待測物之辨識，其檢測過程相當耗時，且用於標記之試劑有危害環境的風險。相較之下，液晶生物感測器具無標記、快速、低汙染之優點，然而其感測之穩定度與靈敏度仍略顯不足。本論文提出改善液晶免疫檢測技術之方法，開發出超高靈敏度之液晶免疫感測器。由實驗結果顯示，相較於液晶5CB，以高折射率液晶做為感測材料，於偵測相同濃度之待測物時，能造成較顯著的光學紋理。此外，本研究透過紫外光修飾感測器之配向層，使待測物更易吸附於配向層表面，進而提高液晶免疫檢測之再現性與靈敏度。我們將此項液晶免疫檢測技術實際應用於癌症生物標記CA-125之篩檢，透過液晶材料的選擇與感測器表面的修飾，可降低CA-125偵測極限至10 pg/ml。此外，我們亦對此免疫檢測技術的專一性進行測試，結果顯示在非專一性抗體的作用下，CA-125免疫複合體無法形成，故液晶分子維持在未被擾動的垂直配向。最後，本研究比較了螢光免疫檢測與液晶免疫檢測之靈敏度，螢光免疫檢測之偵測極限為4–5 μg/ml，較本研究所開發之液晶免疫偵測極限高。我們預期未來可將此項技術推廣到其他種類癌症生物標記的免疫偵測，實際應用於臨床癌症篩檢。

關鍵字

液晶 ； 免疫檢測 ； 生物標記CA-125

並列摘要

Conventional label-based immunoassay is time-consuming, and the labeling reagent may result in environmental pollution. In comparison, liquid crystal (LC)-based biosensor is rapid, label-free, and poses lower environmental risk, but its stability and sensitivity remains to be improved. In this work, we proposed two approaches to enhance the sensitivity of LC-based immunodetection. Using liquid crystals of high birefringence as the sensing element, a more significant phase retardation, and thus higher sensitivity, in the presence of biomolecules was observed under a crossed polarized microscope compared to 5CB, a type of liquid crystal commonly studied in LC-based immunoassay. In addition, we applied UV irradiation to the alignment layer to introduce hydrophilic functional groups, which allowed for more stable binding of the analyte. With a liquid crystal of high birefringence and modified alignment layer, the detection limit of LC-based immunoassay for the cancer biomarker CA-125 was lowered to 0.01 ng/ml. In the presence of non-specific antibodies, which were unable to complex with the CA125 antigen and disrupt LC alignment significantly, the orientation of LCs remained homeotropic, suggesting that LC-based immunodetection is specific and sensitive to the formation of immunocomplexes. Finally, we compared the sensitivity of LC-based immunoassay with an array-based fluorescence immunoassay, which has a detection limit of 4-5 μg/ml CA-125, significantly higher than that of LC-based immunoassay. It is expected that the highly sensitive LC-based immunodetection can be applied in the detection of a wider range of biomarker proteins, with the potential of replacing conventional immunoassays used in clinical cancer screening.

並列關鍵字

liquid crystal ； immunodetection ； biomarker CA-125

參考文獻

[41] 洪翠禪，《材料表面的冷電漿聚合及表面接枝聚合水膠在生物醫學的應用》，碩士論文，大同大學材料工程學系(所)，民國96年。

[43] 邱士晉，《不同比率混合之雙溶劑於混合矽烷溶液中對可調預傾角液晶盒》，碩士論文，國立成功大學光電科學與工程研究所，民國97年。

[39] 謝雅玉，《用於微晶片之聚雙甲基矽氧烷基材表面穩定化學修飾》，碩士論文，國立成功大學化學系專班，民國93年。

[38] 黃佳瑩，《發展新表面修飾技術應用於改善生物感測器之功效與專一性》，碩士論文，國立清華大學生物資訊與結構生物研究所，民國101年。

[15] 林家鴻，《非標定式阻抗分析免疫感測器於Enrofloxacin藥物的檢測》，碩士論文，國立中興大學生物產業機電工程學系所，民國96年。