以電漿共振及漸逝波引發散射效應為基礎之陣列偵測生物晶片

Abstract

經過DNA修飾的金屬奈米粒子可用來作為偵測特定DNA序列的分子探針，目前已有多種策略可用來設計微陣列生物晶片。我們知道當金屬奈米粒子被佈植在金膜表面上時，SPR共振角會隨著奈米粒子的種類，數量，以及分佈情況而改變。另一方面，金屬奈米粒子本身對光的散射或吸收行為也會因為上述因素而有所不同。這意味著如果我們先將玻璃基材表面鍍上金膜，再以金屬奈米粒子作為生物分子的標定手段，理論上我們應該可以同時讀到兩種訊號，一種是由金屬奈米粒子本身所發出的散射光訊號。另一種是因等效介電常數變化所引起的反射光訊號。本文嘗試利用這兩種訊號，作為設計以電漿共振為理論基礎的微陣列生物晶片系統，並提出一種建立在奈米粒子所引起的散射頻譜及反射頻譜變化情形的陣列偵測生物晶片架構。此架構基本上透過三種原理來運作： (1).利用透射，我們可以取得晶片在空間上的資訊，做為爾後晶片影像分析及訊號補償的基礎。 (2).接著透過菱鏡偶合的方式，我們可以取得晶片在反射頻譜上的訊號。 (3).最後再透過漸逝波的激發，我們可以觀察到由金屬奈米粒子所發出的散射訊號。 在實驗方法上，透射訊號可以利用掃描器取得，反射訊號則是採用菱鏡偶合的架構實現，而散射訊號目前暫時是以光波導的方式作初步的調查。實驗的初步成果，目前已可利用透射影像對反射影像作空間上的校正，並進而將反射頻譜的訊號整合成整合式影像。散射訊號的實驗，目前也已成功的觀察到由漸逝波所激發的金屬奈米粒子散射行為，可以在濃度低至14.6pM的情況下，量測粒徑40nm的奈米金粒子所發出的散射訊光。本文所提出之架構初步證實在理論上應屬可行，若成功將可取代傳統的螢光染料，成為更靈敏、可靠的生物晶片平台。但真正的實用化仍需更進一步的努力方能實現。

DNA-modified metallic nanoparticles can be used as probes molecules to detect the specific DNA sequences, many hybridization strategies can be used to design the microarray. We know that when the metallic nanoparticles immobilize on the metal surface, the SPR angle will changing with the type, number, and distribution of the nanoparticles. In another hand, the scatter and the absorption behavior of the nanoparticles will also changing with the situation describing above. That means if we plating metal on the glass substrates and use the metallic nanoparticle as our labeling method, we may read the same chip by two total different mechanisms, one is the scattered signals caused by the nanoparticles itself and the other is the reflected signals caused by the changing dielectric constant of effective medium. We attempt to design a new microarray system based on plasmon resonance, and propose a new array detecting structure that can read the information contained in a chip both through the SPR spectrum and the evanescent wave induced scatter. (1).By transmission, we can get the spacial information that can used to perform the griddling in the following procedure. (2).Through the prism coupling, we can get the reflected signal of the chip. (3).Through the excitation of evanescent wave, we can get the scattered signal emitted from the metallic nanoparticles. About the experimental method, the transmission signals can get from the scanner, the reflecting signals were obtained from the Kretschmann mode, and the investigations on scatter signals so far were performed by wave guide coupling method. About the preliminary achievement, we have successfully aligned the reflecting images by the scanned images, and can further integrate the streaming reflecting images into the integrated image. About the scattering signals experiment, we already can observe the evanescent wave induced scattering through the wave guide coupling method, under this structure, we can detect the scattered signal from the 14.6pM 40nm gold nanoparticles. Therefore the proposed structure of this thesis has been proved possible preliminarily. If the structure works, it may replace the conventional fluorescent labeling method and becomes a more sensitivity, reliable biochip platform. But the practical realization still needs more efforts to achieve.