整合氣泡閥門與奈米流道預濃縮器的生物標記物檢測方法

A new biomarker detection method by integration of oscillating-bubble valves with nanofluidic preconcentrator

鄧志宗(Chih-Zong Deng)

指導教授 ： 沈弘俊

國立臺灣大學/工學院/應用力學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201601817

摘要

本研究成功開發了一種新型檢測方法，整合了預濃縮機制(preconcentration mechanism)、聲學激發震盪的氣泡閥門(acoustically excited oscillating-bubble valve)、以及布朗運動檢測(Brownian motion detection)。首先，利用微影製程技術，製作出微米級流道，再將此兩條流道中間，舖以多孔性奈米材料Nafion，作為離子選擇性薄膜(ion-selective membrane)，其中微米級流道上設計有兩對凹槽，當流體通入微流道時，因為表面張力與微流道本身材料之疏水特性，微型氣泡將會生成於凹槽中。
本研究之生物樣本為C反應蛋白(C-reactive protein, CRP)，是一種研究上常使用的非特異性的反應蛋白。實驗時，先將修飾於335 nm螢光奈米粒子(fluorescent sphere)的anti-CRP與不同濃度的CRP混合後，通入微流道中，再施加電位差於Nafion的兩端，以產生濃度極化效應(Ion Concentration Polarization, ICP)，此時一端為離子富集區(ion enrichment region)，另一端為離子空乏區(ion depletion region)，接者在空乏區一側施加偏壓，便可利用第二種電滲流 (electroosmosis of the second kind)，使空乏區之高電壓側產生濃縮區塊(preconcentration plug)，此時因為流道的特殊設計，濃縮區塊會穩定的停滯在流道特定位置的腔體內。濃縮區塊產生後，啟動事前黏附在晶片上的壓電片(piezoelectric transducer)，調整至適當的振幅及特定的頻率後，於流道凹槽裡位於濃縮區塊兩側的氣泡對，將因為壓電片震動產生特定的共振頻率，而快速膨脹，直到可以完全阻擋流道，進而捕捉濃縮區塊。之後，由於無電位差及壓力差，流體呈現靜止狀態，此時以粒子追蹤測速儀(Particle Tracking Velocimetry, PTV)量測螢光粒子的布朗運動速度，並進行分析。當anti-CRP因與CRP有專一性而互相鍵結，螢光粒子的布朗運動速度會因為粒子變大而減緩，而布朗運動速度降低的程度可作為待測樣本濃度高低的依據。
此種感測技術可廣泛應用在蛋白質或是病毒感測，可以達到快速、價格低廉、且可及時(real-time)感測。此研究成功地可以量測低濃度之CRP，再利用預濃縮機制，可達到極低偵測極限(0.105 ng/ml)的效果。

關鍵字

布朗運動 ； 氣泡閥門 ； 粒子追蹤測速儀 ； C反應蛋白 ； 生物感測技術

並列摘要

In this study, we demonstrate a new integrated detection method to achieve ultra-low detection limit and high sensitivity. This technique used via electrokinetic trapping (EKT)-based nanofluidic preconcentration mechanism, Brownian diffusion and oscillating trapped bubbles. The geometry-trapped bubbles can be triggered to oscillate at resonance frequency by acoustic wave. This acoustically excited oscillating bubble valves haves several advantages: (1) simple fabrication (one layer compareds to multiple-layer of pneumatic valve), (2) perfect channel-blocking channel perfectly (without leakage problem), (3) multiple valves which can be selectively turn off easily. For immunoassay, the oscillated bubbles grew rapidly to block the microchannel and led to trap preconcentrated antigen plug and antibody-coated nanobeads. The antigen concentration can be quantitatively analyzed by real-time measurement of the immunobeads Brownian diffusion. The test sample is C-reactive protein (CRP) which), CRP is a risk indicator of coronary heart disease and atherosclerosis. The level of CRP increases also response to inflammation, infection and tumor etc. This biomarker is widely used to predict coronary events
In conclusions, we developed an integrated biosensor that can haveachieve sample preconcentrating, sample collecting, and sample concentration sensing. The concentrating factor can reach up to 〖~10〗^6 〖~10〗^6 and the sample plug can be trapped by bubble valves after collecting. Thus, an ultra-sensitive (as low as 0.105 ng/ml) and fast (10 minutes) immunoassay can be achieved.

並列關鍵字

preconcentrator ； oscillating microbubble ； nanofluidic ； immunoassay ； C-reactive protein ； Brownian mtion ； micro-Particle Tracking Velocimetry (μ-PTV)

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