Detection of Anti-epileptic Drug Valproic Acid by Piezoresistive Microcantilever Biosensor with Electric Field Enhanced Probing Protein Immobilization

隨著近年來社會走向高齡化的趨勢下，對於生醫檢測晶片的需求也日漸增大，對此，本研究建立於微奈米機電系統技術平台下發展生醫感測晶片，並以一個跨領域的整合式系統，具有可攜式、微型化、低成本、高靈敏度、少量檢體、免螢光標記、快速檢測的優勢，以改善傳統大型且高成本的量測設備，研究探討電場操控蛋白質佈植之壓阻微懸臂梁感測系統，對於抗癲癇藥物丙戊酸(Valproic acid)的藥物監測，由於此為常用的藥物，且藥物在血液內濃度過高會導致不良反應(ADR)，因此可見藥物監測之重要性。 以壓阻式微懸臂梁發展免螢光標定之生物感測器，生物訊號以力學基礎轉換成電阻訊號做為量測生物濃度的辨識，測量前與自組裝分子(SAM)鍵結後，再與辨識元蛋白(Probing protein)接合固定後，便可量測藥物的反應量。而生物感測器由於在固定辨識元蛋白不良時，造成測量藥物的反應量較小而不易辨認。本研究利用控制不同酸鹼值的溶液環境使辨識元蛋白帶正電性，以電場操控之技術提升辨識元蛋白於壓阻式微懸臂梁感測表面的固定效率，藉此提升藥物測量的反應量。並在上流道設計增加銦錫氧化物(ITO)導電薄膜，結合微懸臂梁內的壓阻作為一對電極成為具有電場操控之微懸臂梁生物感測器。運用電場操控辨識元蛋白質高效率佈植，討論不同電壓下對辨識元蛋白固定後量測丙戊酸(Valproic acid)之影響，實驗成功在電壓60 V下提升辨識元蛋白固定效率後提高測量丙戊酸(Valproic acid)反應3倍之多，而在藥物濃度監測中，在電壓30 V與60 V下成功的定性與定量分析出丙戊酸(Valproic acid)濃度50 ~ 500 μg/mL。 本研究利用電場操控辨識元蛋白之技術，增加辨識元蛋白之固定效率，在此情況下可提升測量的反應量，換個角度看，在同樣的反應量下可減少辨識元蛋白檢體的濃度，以降低生物樣品浪費，對於壓阻式微懸臂梁生物感測器上發展策略性之規劃。Therapeutic drug monitoring is a growing issue to measure specific drugs at timed intervals in order to maintain a relatively constant concentration of the medication in the bloodstream. Recognition and quantification of bio-molecules are irreplaceable in biomedical tests and disease diagnosis. This study focus on the piezoresistive microcantilever biosensor embedded with electrodes for manipulation and enhancement of probing protein immobilization onto sensing surfaces. The electrically protein-manipulated, nanomechanics-based biosensor is featured with significant reduction of usage in probing biomaterials, low production cost and high sensistivity; in addition, real-time detection provide immediate and efficient cares for patients at home or bedside point of care. Connecting ITO conductive film and piezoresisitive film in microcantilever, to fabricate a biosensor that is capable of manipulating electric field. Based on changes in electrical charges of the protein in different solution environments, the approach in this study enhanced the immobilization efficiency of probing protein onto the surfaces of microcantilever by applying electric field. As expected, most charged proteins distributed in solution are effectively attracted onto the sensing gold within electric field in high voltage. Under the influence of electric field, the experiment successfully increased the effectiveness of probing protein immobilization by 3 times in which the microcantilever was used in real-time measurement of Valproic acid drug, and its deflection indicates a proportional concentration amount of antigen-antibody interaction. The Valproic acid drug concentration of 50~500 μg/mL has been demonstrated by using this microcantilever biosensor with manipulating electric field