The fabrication of Au-Ni coaxial nanorod arrays with applying in biosensor and tissue engineering

Abstract

In this research, a novel method of fabrication for the growth of Au-Ni coaxial nanorod arrays using AAO templates was investigated. A thin Au film was deposited on one side of the AAO template by sputtering, which was used as the electrode for further electroforming of the Ni nanorods. Nickel nanorods were then electroformed into the nanochannels of the AAO template. Sodium hydroxide solution was then used for etching off the alumina of the AAO template to form a Ni nanorod array. The immersion gold (IG) method was used for forming an Au shell that wrapped each individual Ni nanorod. The average diameter of the synthesized Ni nanorods was estimated to be 100-150 nm. After the IG process, the average thickness of the additive Au shell was about 50-100 nm. Since the height of the synthesized coaxial nanorod was around 30m, the aspect ratio was calculated to be 100-140. Compared to the already reported Au nanorod arrays having an aspect ratio of only around 20, our Au–Ni nanorod array could provide an enhanced effective sensing area. A two-dimensional magnetic force was employed as the actuating source to drive the patterned Au–Ni coaxial nanorod array to move in both x and y directions. Because of the ferromagnetic characteristics of the Ni core, the 2-D movement of the Au–Ni nanorod array could be manipulated by the magnetic force.

The proposed Au-Ni coaxial nanorod arrays were further used for the fabrication of high sensitivity glucose biosensors. Actual glucose measurements revealed that the proposed biosensing scheme could operate in a linear range of 27.5 μM-27.5 mM with a high sensitivity of 778.2 μA mM−1 cm−2. Long-term stability of the proposed device was confirmed through 30-day investigation; Biocompatibility of the proposed Au–Ni coaxial nanorod array was confirmed through the culture of endothelial cells (ECs) on the array surface. Preliminary investigation of the influences of the array stiffness in terms of its height on cell morphology and cell division were conducted. The cell culture results indicate that the cell expanded more on the higher nanorod array. The Au–Ni coaxial nanorod array will be further investigated for effective induction of stem cell differentiation.

本研究提出一種新的高深寬比金鎳同軸奈米柱製程，其製程為先製作陽極氧化鋁膜(AAO)做為模板 接著於 AAO 其中一側濺鍍金薄膜做為電鑄製程之電極，再利用奈米電鑄技術 將金屬鎳沈積於奈米孔洞中 接著以氫氧化鈉蝕刻氧化鋁，形成金屬鎳奈米柱陣列，最後再以浸金(IG)之方法使金沉積於每根鎳奈米柱表面，而製作出高深寬比磁性金鎳同軸奈米柱陣列；鎳奈米柱之平均直徑約為 100-150nm，而經過浸金處理後之金殼厚度可控制在 50-100 nm，又同軸奈米柱之高度可達 30 μm，所以其深寬比可達 100-140 之範圍內，對比於一般金奈米柱之深寬比僅 20，本研究所提出之金鎳同軸奈米柱可以提供更多的有效感測面積；因金鎳同軸奈米柱是屬於磁性材料，所以可藉由兩方向的電磁致動系統使金鎳同軸奈米柱作動。

本研究進一步將所製作之金金鎳同軸奈米柱陣列應用於製作葡萄糖感測器，藉由實際的葡萄糖檢測之結果顯示，本研究所提出之生物感測器之感測線性範圍為 27.5 μM-27.5 mM，並且具有極高的靈敏度 778.2 μA mM−1 cm−2，且其在長時間穩定性測試之結果可達 30 天之久；本研究接著將內皮細胞培養於金鎳同軸奈米柱上，證實金鎳同軸奈米柱陣列確實有生物相容性之特點，並發現金鎳同軸奈米柱之高低差異導致之柔軟度差異，可引導細胞之不同型態生長與分生，實驗結果發現內皮細胞對於較高之奈米柱陣列有較佳的貼附形態且有較佳之增生分化效果，因此可藉由控制金鎳同軸奈米柱之高低調控細胞之型態及增生分化，未來可將幹細胞培養於不同柔軟度之金鎳同軸奈米柱上，並進一步研究及探討以本研究之金鎳同軸奈米柱陣列誘導幹細胞分化成特定之組織細胞。