以介電濕潤及絕緣介電泳研發微粒子親合生物感測晶片

Abstract

於本論文中，我們應用絕緣介電泳和介電濕潤理論，設計一簡易的蛋免疫感測裝置。基於微粒子具有表面積對體積比大，且可接上不同官能基，以接續其他化學反應的特性，我們將抗原接於微米級的聚苯乙烯球。由於抗原及抗體間有極強大的親合力，抗原和帶有螢光基團的抗體會結合，進一步行偵測蛋白質的實驗。我們藉介電濕潤造成液珠親疏水性改變的現象驅動液珠，將抗原及抗體混合直到反應平衡。當帶有螢光基團的蛋白質與接有卵白素的聚苯乙烯球結合後，利用絕緣介電泳驅動微粒子；在試片授予適當頻率和電壓時，微粒子便會極化並趨向電場梯度小的區域，而達成集中的目的。此目的在於增加螢光訊號的強度，以便降低偵測極限，使微流體生物晶片可偵測的蛋白質濃度低於傳統免疫分析可偵測的濃度。藉由將低濃度抗體集中附著於固體上，螢光訊號將增長為原先的3*106倍。而可被偵測的濃度可低達1 pg/mL，偵測時間約為5分鐘。

Here, we present a simple microfluidic affinity-based immunosensor according to principles of electrowetting-on-dielectric (EWOD) and insulator dielectrophoresis (iDEP). We labeled biotin with polystyrene beads which are able to not only perform various chemical characteristics by labeling different functional groups, but also offer an increased surface area for antibodies or antigens to immobilize on. Due to the affinity between biotin and streptavidin, they bound to each other forming biotin-strptavidin-transducer. We can further detect streptavidin by fluorescence. We used EWOD force, changing the wettability of a dielectric solid surface, to move droplets. Furthermore, mixing biotin-labeled polystyrene beads and streptavidin until the reaction achieved equilibrium. With appropriate electric field and frequency, microbeads can be concentration to low electric field region due to the difference of dielectric properties. The purpose of this concentration step was to enlarge the fluorescence signal of analtye and decrease the detection limit of it. With this immunosensor, we can detect lower concentration of analyte than conventional immunosensor. Concentration of streptavidin from dilute solution onto the solid phase was demonstrated, with signal gains of ~3*106 possible. The calibration curve was obtained for concentrations down to 1 pg/mL, for an incubation time of 5 minutes in our immunosensor system.