以聚吡咯修飾矽奈米線陣列應用於生物感測器

Abstract

本研究證實可利用一低成本銀輔助無電鍍蝕刻(Electroless metal deposition, EMD)製備高密度且垂直之單晶矽奈米線陣列。其方式簡單，可在常壓、大氣與水相條件下，不需外加任何形式能量，即能製備矽奈米線陣列。本研分為兩部分探討，第一部分為銀輔助無電鍍蝕刻製備最佳參數之矽奈米線陣列；第二部分為聚吡咯(Polypyrrole, PPy)對最佳化參數之矽奈米線進行表面改質，固定交聯劑戊二醛(Glutaraldehyde, GA)、架接生物分子牛血清蛋白(Bovine serum albumin，BSA)與偵測硫酸鋅(Zinc sulfate，ZnSO4)。

第一部分探討不同銀觸媒大小對合成奈米線之影響，並以銀觸媒輔助無電鍍蝕刻方法找出最佳參數之矽奈米線陣列。由實驗結果顯示，本研究最佳化預沉積銀觸媒為蝕刻3 min。預沉積時間太短，銀顆粒較為密集，導致無法蝕刻出奈米線；預沉積時間過長，銀之樹枝狀太大，使形成的奈米線之間距較大。此外，使用4.6 M氫氟酸和0.5 M過氧化氫混合溶液輔助蝕刻奈米線陣列探討最佳化預沉積銀觸媒參數於不同蝕刻時間，對矽奈米線成長之影響，其結果顯示，矽奈米線之長度與蝕刻時間有成正比之趨勢。而在X光繞射分析儀(XRD)分析下，在2θ=69o，有一較明顯衍生峰，其屬於Si(400)，由不同蝕刻時間比較，55 min之蝕刻時間為最佳參數，而且得知奈米線成長的方向與矽基板相同，證實本研究利用金屬無電鍍蝕刻之方法可製作出單晶矽奈米線陣列。

第二部分為利用聚吡咯對最佳化參數之矽奈米線進行表面改質，並將批覆性均勻性較好之試片進行生物固定化以及鋅離子偵測。由實驗結果得知，改質時間為48 hr可得到較均勻聚吡咯薄膜於矽奈米線陣列表面。另外，由其他分析結果證實聚吡咯確實披覆在矽奈米線陣列表面並觀測到有助於之後做生物分子之架接(grafting)之N－H stretching吸收峰；改質後之試片與戊二醛(Glutaraldehyde, GA)作交聯作用，由FTIR分析中，N - H峰值明顯下降，表示聚吡咯之胺官能基與戊二醛之醛基作鍵結。接著架接牛血清蛋白(Bovine serum albumin, BSA)，其 N - H 與 C＝O之吸收峰值增強，表示GA與BSA具有化學鍵結；另外，鋅之偵測部分，從XRD、FTIR與EDS分析結果，可得到有鋅與硫酸鋅之訊號，且濃度偵測達0.1 mM，表示本研究之創新表面改質為一新穎且具有可行性的方法；未來，若將此系統發展成一生物感測器，不僅可以用來偵測及定量環境中的重金屬含量，同時也能用來偵測血液中的金屬含量。

A simple and low in cost approach to generate silicon nanowires (SiNWs) of single-crystalline, well-aligned, and large area has been synthesized via a silver assisted electroless metal method. The aims of this study are divided into two sections, (1) effect of the different size silver catalyst in the fabrication of silicon nanowires (SiNWs) array via EMD method and (2) polypyrrole conductive polymer was used to modify SiNW arrays, and immobilized BSA with glutaraldehyde cross-linking. The results show that the best of silver catalyst size in the fabrication of SiNW arrays was 3min.When the pre-deposition times of silver catalyst are too short or too long, SiNW arrays could not be formed in this study. When pre-deposition time is too short, the silver particles were more dense lead to SiNW arrays has been not synthesized. When pre-deposition time is too long, too much silver dendrite was fabricated lead to larger spacing.

Large-area ordered single crystal SiNW arrays on p-type (100) silicon wafer without the use of a template were prepared in a hydrofluoric acid and (HF / H2O2) solution at 50oC by silver assisted electroless etching (pre-deposition silver catalyst for etching 3min). The result showed that highly dominant peak at 69° is belong to (400) silicon plane which can be explained equally by preferential etching along [100] directions. The linear relationship of SiNW arrays could be adjusted by controlling the immersion time.

On the other hand, polypyrrole conductive polymer treatment was confirmed to be an effective precursor to the introduction of amine functionalities onto the SiNW arrays surface, to enhance their biocompatibility. The results show that the best immersion time of PPy modifying SiNW arrays was 48hr. The amine (NH2) functional groups were incorporated on the SiNW arrays surface by FTIR analysis. The glutaraldehyde (GA) was used to cross-link the amino (NH-) functional groups with bovine serum albumin (BSA) onto the PPy-SiNW arrays surface. In addition, the bovine serum albumin (BSA) detection Zn signal was investigated by FTIR, energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) measurements. The results demonstrate Zn signal could be detected. The lower concentration of ZnSO4 at 0.1 mM also could be detected. Therefore, these results demonstrate that the induction of amino groups onto SiNW arrays surface, using polypyrrole conductive polymer treatment, is an novelty, effective and reliable method which could be expected to have favourable applications in biosensor.