新穎多晶矽奈米線場效電晶體於人類血清攝護腺特異抗原之免標定即時偵測

Abstract

應用場效電晶體 (field-effect transistor, FET) 偵測生物分子，在疾病診斷與預防醫學等領域為一門具有發展潛力之新穎科技。在此研究中，我們主要利用簡單且價格低廉的半導體製程技術製作奈米線場效電晶體，藉由側壁蝕刻技術 (sidewall spacer technology) 取代傳統昂貴的電子束微影 (E-beam lithography) 製作多晶矽奈米線場效電晶體作為生物感測器，運用其即時偵測、免標定且高敏感度等特性，用於偵測人類血清中的攝護腺特異抗原 (prostate-specific antigen, PSA)。我們首先利用自組裝技術將3-aminopropyltriethoxysilane (APTES) 修飾於silicon oxide表面，接上glutaraldehyde作為連結之後，再與所要偵測之抗原相對應的抗體鍵結，在適當的pH值以及離子強度之下，結合微流道系統，其偵測極限可達5 fg/mL。由於血清中的成分極為複雜，含有高濃度的鹽類及其他干擾因子，為了將此系統應用到人類血清之中，我們發展了一套標準作業流程來處理真實檢體以維持去鹽血清在適當的pH值及離子強度，並且利用Tween 20修飾在奈米線上排除血清中非特異性的靜電吸附以達到醫療診斷上之應用。在未來的應用上，此新穎多晶矽奈米線場效電晶體在監控癌症及預後追蹤上皆為極具發展潛 力之偵測平台。

The application for disease diagnosis and recurrence prevention of high-sensitive field-effect transistor devices in detecting the biomolecules is a novel and developing technology. In this research, we used poly-silicon nanowire field-effect transistor (poly-Si NWFET) as biosensor which was fabricated by employing the sidewall spacer technique instead of expensive E-beam lithography method. The sidewall spacer technique has the advantages of simplicity and low-cost, comparing to the current commercial semiconductor process. By using these novel devices which exhibited characteristics of real-time, label-free and ultrahigh-sensitive, we could detect prostate-specific antigen (PSA) in human serum in this thesis. We firstly modified 3-aminopropyltriethoxysilane (APTES) on the silicon oxide surface followed by glutaraldehyde functionalized, and the PSA antibodies were immobilized on the aldehyde terminal. While PSA were prepared in the buffers maintaining appropriate pH values and ionic strength, the results indicated that the sensor could detect trace PSA which was down to 5 fg/mL in a micro-fluidic channel. Since serum proteome is very complex containing high levels of salts and other interfering compounds, we hereby developed a standard operating procedure for real sample pretreatment to keep a proper pH and ionic strength of the desalted serum, and also utilized Tween 20 serving as the passivation agent by surface modification on the nanowire to reduce non-specific binding for medical diagnostic applications. The novel poly-silicon nanowire field-effect transistor as diagnostic platform for monitoring cancer therapy and predicting the risk of early biochemical relapse is potential and developed in the future.