利用電場操控蛋白質佈植於高靈敏度之微懸臂樑生化感測器

Abstract

微懸臂樑生化感測器主要結合了光學、微機電和流體系統三種技術，即是當生物分子薄膜形成在微懸臂樑表面時，用光槓桿原理偵測微懸臂樑的彎曲。此感測器的優點在靈敏度高、不需螢光標記、可偵測小分子反應的訊號、將來有平行化檢測的潛力且靠半導體製程大量製造節省成本。 本實驗在此感測器之研究領域，首次利用蛋白質等電位點的概念結合電場操控技術，希望達成操控蛋白質佈植的功能。本研究設計了三組實驗，分別在淨電荷帶正電之免疫球蛋白G1(IgG1)吸附於微懸臂樑表面時通入-10V、0V和+10V不同的電壓。實驗結果顯示-10V形成的電場的確可以吸引更多的蛋白質在吸附微懸臂樑表面，造成較大的彎曲量；相反的，+10V形成的電場的確可以排斥蛋白質避免吸附在微懸臂樑表面，造成較小的彎曲量。本實驗成功地做到了利用電場吸引和排斥蛋白質，證實可用電場決定蛋白質附著於微懸臂樑表面的密度，更可連續量測微懸臂樑的彎曲量，了解整段免疫檢測的過程。 本研究期望吸引的功能將來可應用在蛋白質晶片上，減少低濃度珍貴蛋白的使用量，另一方面當醫療產業大量製造蛋白質晶片時，可減少檢測用蛋白質的使用量。期望排斥的現象將來可應用在多個反應區的選擇性佈植，可將每個反應區附著上不同的檢測用蛋白。 現今生物醫學的發展不斷進步與許多創新技術的開發息息相關，其中最重要的莫過於人類對於微奈米尺度下科學和技術的掌握，而微機電技術正是切入這些問題核心的好方法，我們也用此技術發展微懸臂樑生化感測器。

It is becoming gradually obvious that the high-throughput recognition and quantification of bio-molecules are of great importances in biomedical detection and disease diagnosis. With the growing interest and fast development in bio-nanotechnology, bio-sensing tools have been moving towards miniaturization, high sensitivity, and great promise in low-cost as well. A novel electric field-manipulated biosensor of label-free biomolecular recognition based on the nano-mechanics transduction in a micro-fabricated cantilever has been developed. Use of inherent protein charge not in an isoelectric point state is proven to be driven in an electric field, commonly seen in electrophoreses processes. Several electric field-manipulated experiments were conducted between the electrodes of -10V, +10V, and no voltage applications. It was found that the sensing area of the electrode with -10 volt was collectively deposited with the net positive protein IgG1 in a buffer solution of pH ~ 5. The significant surface stresses arise in sensing area as a negative electrode, while most proteins are, in contrast, repelled out of the sensing area applied in positive electrode. With the protein isoelectric point characteristics, the attraction and repulsion of proteins have been demonstrated in manipulation under electric fields across the electrodes with the device sensing element. In protein attraction demonstration, the device is capable of highly sensitive antigen detection by collecting most antibodies in a far dilute concentration. In addition, both use of attraction and repulsion in manipulation show the potential of selective deposition and local repulsion in specific sensing surface among multiple disparate sensing agents.