利用壓阻式微懸臂梁感測器偵測血清中抗癲癇藥丙戊酸

Abstract

近年來，罹患癲癇的人數逐漸增加，也使得抗癲癇藥物的需求相對成長。然而，統計發現更多病患由於缺乏完善的檢測而發生藥物不良反應。藥物治療監測系統可用來解決藥物不良反應的問題，因為此系統可以適當控制藥物濃度在50-100μg/ml的有效治療範圍。當病患的血中藥物濃度超過監測濃度範圍時，會使病患有中毒的反應；若濃度低於監測範圍，則會使藥物無法對病患發揮療效。目前常見的藥物監測系統主要是以螢光標定為基礎，例如：螢光偏極免疫分析法以及氣相色譜法–質譜法聯用等。但由於需要螢光標定的關係，這些方法都較為耗時，檢測結果有賴操作者的判斷，並且需要複雜的運作機器。本研究成功設計開發出一微懸臂梁，可用於量測有效治療濃度範圍內的抗癲癇藥物─丙戊酸，實驗中我們選用了50, 100, 200以及500 μg/ml的濃度進行量測。由於蛋白質在pH值低於其pI值的溶液中帶正電；在高於其pI值的溶液中帶負電，因此實驗中所使用之磷酸鹽緩衝溶液的pH值介於抗體與抗原的pI值之間 (4.8-5.6), 使抗體與抗原帶不同電性而結合。最後為了驗證此為懸臂梁能應用於臨床檢測，本研究以分別含50%以及100%的胎牛血清環境進行藥物檢測並成功分析出其對應的表面應力分別為0.48 以及 0.24 N/m，經過計算得到解離常數為80。此外，將相同樣本以微懸臂梁和螢光偏極免疫分析法進行量測，得到相符的結果，驗證此晶片確實能取代傳統儀器之分析。壓阻式微懸臂梁擁有微型化、低成本、免螢光標記等優勢，未來配合後端電路整合即可使其在醫院以外地方也能進行檢測，達到居家照護的功效。

The number of seizures patients in the world has been increasing from year to year. This makes the consumption of anti-epileptic drugs increase accordingly. Moreover, the number of adverse drug reactions will consequently rise due to lack of careful monitoring. Therapeutic drug monitoring (TDM) is the key answer to solve this problem, since TDM system using valproic acid drug can be used to treat seizure at concentration around 50-100 μg/ml. Recent methods used for detecting TDM on patients are mainly label-based methods, fluorescence polarization immunoassays (FPIA). Unfortunately, those methods are dependent on labels, which mean that they are time consuming, operator dependant and also heavily dependent on complicated machinery. Therefore, the demand for rapid analysis is becoming significant for TDM particularly for seizures patients. In this research, microcantilever biosensor is expected to answer those challenges. In this study, a piezoresistive microcantilever biosensor was designed to detect the valproic acid drug concentration in a suitable therapeutic range, such as 50, 100, 200 and 500 μg/ml. Since proteins are positively charged in solutions at pH values below their isoelectric point (pI) value and negatively charged above their pI value, phosphate buffer saline (PBS) was prepared at a pH value between antibody (Ab) and antigen (Ag) pI values (4.8-5.6) so as to activate Ab and Ag. In order to determine the suitability of this microcantilever biosensor in clinical settings, detection in 50% and pure fetal bovine serum (FBS) was also conducted, resulting the surface stress value 0.48 and 0.24 N/m, respectively. The value of dissociation constant (KD) was 80. The comparison and limitation result to the conventional method (FPIA) was conducted on PBS and serum buffer. Those values give a promising result for microcantilever biosensor to be further developed on the wireless point-of-care system.