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多孔硅生物化学表面修饰研究
Study of Biochemical Surface Modification of Porous Silicon
【作者】 王庆元；
【导师】 李怀祥；
【作者基本信息】 山东师范大学 ， 物理化学， 2011， 硕士
【摘要】 本实验研究包括以下几个内容:1.多孔硅电极制备及其检测抗坏血酸的研究本实验通过电化学阳极氧化方法制备多孔硅,并用多孔硅作为研究电极对抗坏血酸进行检测。通过LK-2005型电化学工作站测定塔菲尔曲线、线性扫描曲线来进行分析电压,电流,pH与抗坏血酸浓度之间的关系。实验研究表明同一电压下电流随着抗坏血酸浓度的增大而增大。随着抗坏血酸浓度的增大,塔菲尔曲线整体往正电位方向平移。在抗坏血酸溶液浓度为1.0g/L条件下测得电流值随着pH的减小而逐渐增大,但不成良好线性关系。多孔硅电极表面修饰一层银与未修饰的多孔硅对同一浓度的抗坏血酸测量塔菲尔曲线比较,修饰后的电极在相同浓度和电位情况下电流明显的增大。2.生物功能化的多孔硅对尿素溶液的检测研究用3-氨基丙基三乙氧基硅烷（APTS）对多孔硅表面进行处理,在780℃通入Ar气的条件下对其高温退火,使多孔硅表面形成大量的氨基基团,使其作为前躯体,通过共价键结合的方法,能够很好的固定生物分子,然后用尿素酶进行处理并对0.4×10-3mol/L～8.0×10-3mol/L范围内不同浓度的尿素溶液进行检测。经过研究发现生物功能化的多孔硅对尿素溶液具有良好的传感性和可重复检测性。3.多孔硅复合酶电极对葡萄糖溶液传感的研究多孔硅（PS）具有纳米级尺寸,大比表面积,生物兼容性的特点为固定生物分子提供了有利的条件。本文采用光电化学腐蚀的方法,制备出新鲜的多孔硅,并将3-氨基丙基三乙氧基硅烷（APTS）共价结合到多孔硅表面实现其生物功能化。通过戊二醛（Gluta）交联的方式将葡萄糖氧化酶（GOD）固定到生物功能化多孔硅上,形成GOD-Gluta-APTS-PS复合结构并用作电化学测量的工作电极。铂金和饱和甘汞电极分别作辅助电极和参比电极。通过测量还原电流对数与电极电势的关系以及计时电流曲线,对10×10-6—55×10-6 mol dm-3浓度范围的葡萄糖水溶液进行测量分析,发现还原电流与葡萄糖溶液在在一范围内有线性响应关系。制成的多孔硅酶复合电极间隔5天重复使用1次,20天能保持性能基本不变。
【Abstract】 This experimental study includes the following contents:1. Electrochemical detection of ascorbic acid by porous silicon electrode Porous silicon prepared by electrochemical anodic oxidation and modified through biofunctionalization surfaces has been used to detect ascorbic acid. The relationship between ascorbic acid concentration and voltage, current, pH has been analyzed, respectively, by measuring Tafel curve, linear sweep curves with electrochemical workstation LK-2005. Experimental studies have shown that current increases with the concentration of ascorbic acid at a given voltage, Tafel curves shift toward positive potential with increase of ascorbic acid concentration. The current increases with decrease of pH values, but there was not a goog linear relationship. Surface modification of porous silicon has been conducted by silver layer and the modified electrode showed greater current than non-modifited electrode at same ascorbic acid concentration and same potential from the measurement of Tafel curve.2.Biological function of porous silicon on the biological sensing of urea solutionA unique electrode based on aminopropyl-triethoxysilane （ APTS）-coated porous silicon（PS） substrate has been fabricared and used as a urea-sensitive electrode after urease immobilization. PS substrate was formed by electrochemical anodization in an etching solution composed of HF and ethanol. APTS layer was formed on the PS surface by coating and heating at 780℃in argon atmosphere. Urease immobilization was carried out by immersing the APTS/PS in urease solution. The immobilized system gives linear response for concentrations of urea ranging in values between 3.6×10-3 and 8.0×10-3 mol dm-3 , studied with voltammetry. The surface of biofunctionized porous silicon has thus provided a suitable environment for urease with 15 days retention of its activity. The molecular structure on the PS surface was characterized with Fourier-transform infrared （FTIR） technique. The change in the surface morphology has been studied by scanning electron microscopy and it is observed that the immobilized system has successfully retained urease. The eleperimental results showed that porous silicon with biofunctionalization surfaces could give a good sensitivity and repeatability to detect urea solution.3. porous silicon enzyme electrode biosensors solution of Glucose.Porous siicon（PS） is provided with characteristics of nanometer size, large specific surface and bio-compatibility. Photoelectrochemical etching technique has been used to prepare a porous silicon substrate which then modified by aminopropyl-triethoxysilane（APTS） to realize biofunctionalization of the surface. Glucose oxidase（GOD） immobilization was carried out by glutaraldehyde（Gluta） cross-linking to the porous silicon and to form GOD-Gluta-APTS-PS composite structure. The GOD-Gluta-APTS-PS structure was used as working electrode mou nted in a measuring cell sealed by an O-ring. A saturated calomel electrode（SCE） and platinum dish was used as reference electrode and counter electrode, respectively. Chrononamperemeter and logarithmic current-popential measurements were performed to detect a glucose solution. Under the selected conditions,the enzyme composite electreode offered a liner response in the glucose concentration range of 10×10-6—55×10-6 mol dm-3. The sensor remained good response after 20 days through 5 days interval measurements.