表面形貌对螺旋线形跨尺度电化学葡萄糖传感器性能的影响

2014-09-02 09:23景蔚萱等
分析化学 2014年8期

景蔚萱等

摘要将键合金丝以螺旋方式紧密绕制在光纤纤芯上,用水浴法在其表面合成氧化锌纳米线,再将葡萄糖氧化酶物理吸附在纳米线上,得到了螺旋线形跨尺度葡萄糖酶电极。提取了该跨尺度结构及相应酶电极的表面形貌,表征了该批酶电极的电化学性能。结果表明,氧化锌纳米线的合成参数对跨尺度结构的表面形貌、葡萄糖氧化酶的固定效果、跨尺度电化学葡萄糖传感器的性能有显著影响; 关键词跨尺度结构; 表面形貌; 葡萄糖生物传感器; 循环伏安法; 计时电流法

1引言

以葡萄糖氧化酶(Glucose oxidase,GOD)和电极表面之间直接电子转移为特点的跨尺度电化学葡萄糖传感器已广泛应用于医药、生物、食品加工、环境监测等领域\[1~4\],其工作电极由微米级基底电极和纳米级基质材料组成\[5\]。氧化锌(ZnO)纳米线的比表面积大、抗氧化能力强、无毒性、生物兼容性好,经常用作基质材料\[6\]。为了批量制备跨尺度电化学葡萄糖传感器,除了研究GOD和葡萄糖之间的电化学行为外,还需对合成参数、跨尺度结构的表面形貌、GOD的吸附效果进行量化表征。

跨尺度电化学葡萄糖传感器基底电极以平面形(沉积有Au膜的平面基底、ITO(Indium tin oxides)导电玻璃等)\[7, 8\]和圆柱形结构(Au或Ag丝、玻碳电极等)\[9~11\]居多,其电极面积需进一步增大。基底电极上ZnO纳米线薄膜的比表面积、表面形貌直接影响GOD的固定效果,但是其比表面积难于测量\[12\],而表面形貌大多采用扫描电子显微镜(Scanning electron microscopy,SEM)的直接测量法,测量参数有限、表征数据单一、表征结果不完整\[13, 14\]。合成参数决定ZnO纳米线薄膜的表面形貌,进而导致不同的GOD固定效果,最终影响该类传感器的高精度、批量制备,因此需要建立这些影响因素之间的定量关系。

本研究在前期工作\[15\]的基础上, 制备了一批基于ZnO纳米线的螺旋线形跨尺度工作电极,对其结构及固定GOD前后的表面形貌进行了定量表征,对酶电极性能进行了电化学测试,初步建立了合成参数表面形貌GOD固定效果跨尺度葡萄糖传感器性能之间的定量关系。

22螺旋线形跨尺度工作电极的制备

螺旋线形跨尺度电化学葡萄糖传感器包括螺旋线形跨尺度工作电极、Ag/AgCl 参比电极、Pt对电极,其工作电极的制备包括微米级圆柱螺旋线的绕制和ZnO纳米线的合成。将双模光纤在丙酮中浸泡5 min,抽出光纤纤芯;将Au丝一端用环氧树脂固定在光纤纤芯一端,再手工紧密绕制在光纤纤芯上,形成轴向长度为3 mm的Au螺旋线;用环氧树脂将Au螺旋线另一端固定在光纤纤芯上,并留出电极引线;用无水乙醇超声清洗Au螺旋线组件,并在真空干燥机中干燥。

水浴法合成ZnO纳米线的工艺参数包括生长液和种子层溶液Zn2+浓度、生长时间和合成温度等。在6个Au螺旋线表面沉积1 mmol/L ZnO种子层,并于150 ℃退火10 min;再重复上述沉积和退火步骤两次。将沉积有ZnO种子层的6个Au螺旋线分别放入Zn2+浓度为0, 25, 50, 75, 100和125 mmol/L的生长液中, 并于90 ℃下保持25 h,取出后用去离子水超声清洗5 min后, 在室温下干燥,得到6种Au螺旋线形跨尺度结构,见图1(a);将螺旋线形跨尺度结构分别浸入40 mg/mL GOD溶液, 并保持30 min,取出后在室温下干燥;用去离子水冲洗多余的GOD,得到6种螺旋线形跨尺度工作电极。

23螺旋线形跨尺度结构及工作电极的表征

基于SEM图像和滤波、线边缘提取、拟合等MATLAB图像处理算子提取出固定GOD前后螺旋线形跨尺度结构的轮廓边缘,据此得到其几何参数(螺距、螺旋角和外廓直径)和表面形貌的特征参数。在粗糙表面的特征参数中,均方根粗糙度Ra(Roughness)是随机变量的2阶矩,描述表面高度相对于中线的波动程度;偏斜度Sk(Skewness)是随机变量的3阶矩,反映表面上凸起和凹坑相对于高斯分布的对称程度;峭度Ku(Kurtosis)是随机变量的4阶矩,表明各点高度相对于高斯分布的分散程度;相关长度ξ(Correlation length)反映轮廓上各点高度之间相关性的范围。

24螺旋线形跨尺度葡萄糖传感器的电化学测试

在0, 1, 2, 3, 4, 5和6 mmol/L葡萄糖溶液中用循环伏安法分析螺旋线形跨尺度葡萄糖传感器的氧化还原能力,扫描电压为

Symbolm@@ 02~08 V,扫描速率50 mV/s;用计时电流法确定螺旋线形跨尺度葡萄糖传感器的灵敏度、线性范围、检出限和MichaelisMenten常数,其中工作电极相对参比电极的偏压为+08 V,且每隔一定时间往50 mL PBS溶液中边搅拌边加入100 μL 025 mol/L葡萄糖溶液,搅拌速度为400 r/min。

332电流时间响应由图3c的电流时间响应曲线可得到图3d的葡萄糖浓度与响应电流平均值的散点图,据此可求出相应传感器的灵敏度、线性范围及检出限; 根据LineweaverBurk方程并结合电流时间响应曲线可计算出MichaelisMenten常数, 结果见表2。显然,生长液Zn2+浓度及跨尺度结构表面形貌对传感器的灵敏度及检出限有显著影响,而对其线性范围和MichaelisMenten常数影响不大。当生长液Zn2+浓度分别为25, 50, 100和125 mmol/L时,传感器的灵敏度越来越减小;生长液Zn2+浓度75 mmol/L所对应的灵敏度要小于100 mmol/L; 生长液Zn2+浓度0 mmol/L对应的灵敏度略差于75 mmol/L;表面形貌导致的不同GOD固定效果是灵敏度产生上述变化的原因。

生长液Zn2+浓度为0, 25, 50, 75和100 mmol/L时所对应的最低检出限相差不大,而125 mmol/L对应的检出限明显大于其它5组。这是因为当生长液Zn2+浓度为125 mmol/L时,重结晶现象最明显,只在ZnO纳米结构的顶面吸附有GOD,且还产生了酶堆积,故其表面有效吸附的GOD最少。4结论

在手工绕制的金螺旋线表面用水浴法合成了ZnO纳米线,并在其上物理吸附GOD,得到了螺旋线形跨尺度电化学葡萄糖传感器的工作电极。初步建立了ZnO纳米线的合成参数生长液Zn2+浓度螺旋线形跨尺度结构的表面形貌GOD固定效果螺旋线形跨尺度电化学葡萄糖传感器性能之间的定量关系。研究结果不但有助于螺旋线形跨尺度葡萄糖传感器的批量制备,还可显著提高其测量精度。

2CHEN HuiJuan, ZHU JianJun, YU Meng Chinese J Anal Chem, 2013, 41(8): 1243-1248

陈慧娟, 朱建君, 余 萌 分析化学, 2013, 41(8): 1243-1248

3Cash K J, Clark H A Trends Mol Med, 2010, 16(12): 584-593

4Mahshid S S, Mahshid S, Dolati A, Ghorbani M, Yang L X, Luo S L, Cai Q Y J Alloys Compd, 2013, 554(25): 169-176

5Arya S K, Saha S, RamirezVick J E, Gupta V, Bhansali S, Singh S P Anal Chim Acta, 2012, 737(6): 1-21

6Jiang P, Zhou J J, Fang H F, Wang C Y, Wang Z L, Xie S S Adv Funct Mater, 2007, 17(8): 1303-1310

7Kim J Y, Jo S Y, Sun G J, Katoch A, Choi S W, Kim S S Sens Actuators, B, 2014, 192: 216-220

8LI LiHua, CAI ZiYou, HUANG YongHong, LI YongChong, ZHANG WeiDe Chinese J Anal Chem, 2012, 40(5): 778-781

李利花, 蔡自由, 黄勇红, 李永冲, 张伟德 分析化学, 2012, 40(5): 778-781

9Pan D W, Chen J H, Yao S Z, Nie L H, Xia J J, Tao W Y Sens Actuators, B, 2005, 104: 68-74

10Syed M U A, Omer N, Magnus W, Bengt D Sens Actuators, B, 2010, 145(2): 869-874

11Qiu C C, Wang X, Liu X Y, Hou S F, Ma H Y Electrochim Acta, 2012, 67: 140-146

12Ahmad R, Tripathy N, Kim J M, Hahn Y B Sens Actuators, B, 2012, 174: 195-201

13Qurashi A, Hossain M F, Faizc M, Tabetc N, Alamd M W, Reddy N K J Alloys Comp, 2010, 503(2): L40-L43

14Zhong G, Kalam A, AlShihri A S, Su Q M, Li J, Du G H Mater Res Bull, 2012, 47(6): 1467-1470

15JING WeiXuan, ZHOU Fan, CHEN LuJia, QI Han, JIANG ZhuangDe, WANG Bing, NIU LingLing Chem J Chinese Universities, 2014, 35(3): 493-498

景蔚萱, 周 帆, 陈路加, 齐 含, 蒋庄德, 王 兵, 牛玲玲 高等学校化学学报, 2014, 35(3): 493-498

AbstractZinc oxide nanowires were hydrothermally synthesized on the surface of an Au cylindrical spiral formed by manually spiraling an Au fiber around an optical fiber core, glucose oxidase was immobilized on these nanowires by physical adsorption, and then a spirally hierarchical structurebased glucose enzymatic electrode was obtained The surface morphologies of the spirally hierarchical structures and corresponding enzymatic electrodes were extracted, and the electrochemical performances of the enzymatic electrodes were characterized It was concluded that the synthesizing parameters of zinc oxide nanowires significantly affected the surface morphologies and glucose oxidase immobilization on the spirally hierarchical structures, and further the performances of related glucose sensors With Zn2+ concentration of the growth solution set at 25 mmol/L, the roughness of surface morphology was determined to be 010 μm and correlation length 029 μm, resulting in a better immobilization of glucose oxidase upon zinc oxide nanowires In this case the sensitivity of the glucose sensor was determined to be 215 μA/(mmol/L·cm2), the linear range was 0-450 mmol/L, the low detection limit was 920 μmol/L and MichaelisMenten constant was 368 mmol/L The results not only benefit the batch production of the spirally hierarchical structurebased enzymatic electrodes, but also significantly improve the performances of the glucose sensors

KeywordsHierarchical structure; Surface morphology; Glucose biosensor; Cyclic voltammetry; Amperometric response

在手工绕制的金螺旋线表面用水浴法合成了ZnO纳米线,并在其上物理吸附GOD,得到了螺旋线形跨尺度电化学葡萄糖传感器的工作电极。初步建立了ZnO纳米线的合成参数生长液Zn2+浓度螺旋线形跨尺度结构的表面形貌GOD固定效果螺旋线形跨尺度电化学葡萄糖传感器性能之间的定量关系。研究结果不但有助于螺旋线形跨尺度葡萄糖传感器的批量制备,还可显著提高其测量精度。

2CHEN HuiJuan, ZHU JianJun, YU Meng Chinese J Anal Chem, 2013, 41(8): 1243-1248

陈慧娟, 朱建君, 余 萌 分析化学, 2013, 41(8): 1243-1248

3Cash K J, Clark H A Trends Mol Med, 2010, 16(12): 584-593

4Mahshid S S, Mahshid S, Dolati A, Ghorbani M, Yang L X, Luo S L, Cai Q Y J Alloys Compd, 2013, 554(25): 169-176

5Arya S K, Saha S, RamirezVick J E, Gupta V, Bhansali S, Singh S P Anal Chim Acta, 2012, 737(6): 1-21

6Jiang P, Zhou J J, Fang H F, Wang C Y, Wang Z L, Xie S S Adv Funct Mater, 2007, 17(8): 1303-1310

7Kim J Y, Jo S Y, Sun G J, Katoch A, Choi S W, Kim S S Sens Actuators, B, 2014, 192: 216-220

8LI LiHua, CAI ZiYou, HUANG YongHong, LI YongChong, ZHANG WeiDe Chinese J Anal Chem, 2012, 40(5): 778-781

李利花, 蔡自由, 黄勇红, 李永冲, 张伟德 分析化学, 2012, 40(5): 778-781

9Pan D W, Chen J H, Yao S Z, Nie L H, Xia J J, Tao W Y Sens Actuators, B, 2005, 104: 68-74

10Syed M U A, Omer N, Magnus W, Bengt D Sens Actuators, B, 2010, 145(2): 869-874

11Qiu C C, Wang X, Liu X Y, Hou S F, Ma H Y Electrochim Acta, 2012, 67: 140-146

12Ahmad R, Tripathy N, Kim J M, Hahn Y B Sens Actuators, B, 2012, 174: 195-201

13Qurashi A, Hossain M F, Faizc M, Tabetc N, Alamd M W, Reddy N K J Alloys Comp, 2010, 503(2): L40-L43

14Zhong G, Kalam A, AlShihri A S, Su Q M, Li J, Du G H Mater Res Bull, 2012, 47(6): 1467-1470

15JING WeiXuan, ZHOU Fan, CHEN LuJia, QI Han, JIANG ZhuangDe, WANG Bing, NIU LingLing Chem J Chinese Universities, 2014, 35(3): 493-498

景蔚萱, 周 帆, 陈路加, 齐 含, 蒋庄德, 王 兵, 牛玲玲 高等学校化学学报, 2014, 35(3): 493-498

AbstractZinc oxide nanowires were hydrothermally synthesized on the surface of an Au cylindrical spiral formed by manually spiraling an Au fiber around an optical fiber core, glucose oxidase was immobilized on these nanowires by physical adsorption, and then a spirally hierarchical structurebased glucose enzymatic electrode was obtained The surface morphologies of the spirally hierarchical structures and corresponding enzymatic electrodes were extracted, and the electrochemical performances of the enzymatic electrodes were characterized It was concluded that the synthesizing parameters of zinc oxide nanowires significantly affected the surface morphologies and glucose oxidase immobilization on the spirally hierarchical structures, and further the performances of related glucose sensors With Zn2+ concentration of the growth solution set at 25 mmol/L, the roughness of surface morphology was determined to be 010 μm and correlation length 029 μm, resulting in a better immobilization of glucose oxidase upon zinc oxide nanowires In this case the sensitivity of the glucose sensor was determined to be 215 μA/(mmol/L·cm2), the linear range was 0-450 mmol/L, the low detection limit was 920 μmol/L and MichaelisMenten constant was 368 mmol/L The results not only benefit the batch production of the spirally hierarchical structurebased enzymatic electrodes, but also significantly improve the performances of the glucose sensors

KeywordsHierarchical structure; Surface morphology; Glucose biosensor; Cyclic voltammetry; Amperometric response

在手工绕制的金螺旋线表面用水浴法合成了ZnO纳米线,并在其上物理吸附GOD,得到了螺旋线形跨尺度电化学葡萄糖传感器的工作电极。初步建立了ZnO纳米线的合成参数生长液Zn2+浓度螺旋线形跨尺度结构的表面形貌GOD固定效果螺旋线形跨尺度电化学葡萄糖传感器性能之间的定量关系。研究结果不但有助于螺旋线形跨尺度葡萄糖传感器的批量制备,还可显著提高其测量精度。

2CHEN HuiJuan, ZHU JianJun, YU Meng Chinese J Anal Chem, 2013, 41(8): 1243-1248

陈慧娟, 朱建君, 余 萌 分析化学, 2013, 41(8): 1243-1248

3Cash K J, Clark H A Trends Mol Med, 2010, 16(12): 584-593

4Mahshid S S, Mahshid S, Dolati A, Ghorbani M, Yang L X, Luo S L, Cai Q Y J Alloys Compd, 2013, 554(25): 169-176

5Arya S K, Saha S, RamirezVick J E, Gupta V, Bhansali S, Singh S P Anal Chim Acta, 2012, 737(6): 1-21

6Jiang P, Zhou J J, Fang H F, Wang C Y, Wang Z L, Xie S S Adv Funct Mater, 2007, 17(8): 1303-1310

7Kim J Y, Jo S Y, Sun G J, Katoch A, Choi S W, Kim S S Sens Actuators, B, 2014, 192: 216-220

8LI LiHua, CAI ZiYou, HUANG YongHong, LI YongChong, ZHANG WeiDe Chinese J Anal Chem, 2012, 40(5): 778-781

李利花, 蔡自由, 黄勇红, 李永冲, 张伟德 分析化学, 2012, 40(5): 778-781

9Pan D W, Chen J H, Yao S Z, Nie L H, Xia J J, Tao W Y Sens Actuators, B, 2005, 104: 68-74

10Syed M U A, Omer N, Magnus W, Bengt D Sens Actuators, B, 2010, 145(2): 869-874

11Qiu C C, Wang X, Liu X Y, Hou S F, Ma H Y Electrochim Acta, 2012, 67: 140-146

12Ahmad R, Tripathy N, Kim J M, Hahn Y B Sens Actuators, B, 2012, 174: 195-201

13Qurashi A, Hossain M F, Faizc M, Tabetc N, Alamd M W, Reddy N K J Alloys Comp, 2010, 503(2): L40-L43

14Zhong G, Kalam A, AlShihri A S, Su Q M, Li J, Du G H Mater Res Bull, 2012, 47(6): 1467-1470

15JING WeiXuan, ZHOU Fan, CHEN LuJia, QI Han, JIANG ZhuangDe, WANG Bing, NIU LingLing Chem J Chinese Universities, 2014, 35(3): 493-498

景蔚萱, 周 帆, 陈路加, 齐 含, 蒋庄德, 王 兵, 牛玲玲 高等学校化学学报, 2014, 35(3): 493-498

AbstractZinc oxide nanowires were hydrothermally synthesized on the surface of an Au cylindrical spiral formed by manually spiraling an Au fiber around an optical fiber core, glucose oxidase was immobilized on these nanowires by physical adsorption, and then a spirally hierarchical structurebased glucose enzymatic electrode was obtained The surface morphologies of the spirally hierarchical structures and corresponding enzymatic electrodes were extracted, and the electrochemical performances of the enzymatic electrodes were characterized It was concluded that the synthesizing parameters of zinc oxide nanowires significantly affected the surface morphologies and glucose oxidase immobilization on the spirally hierarchical structures, and further the performances of related glucose sensors With Zn2+ concentration of the growth solution set at 25 mmol/L, the roughness of surface morphology was determined to be 010 μm and correlation length 029 μm, resulting in a better immobilization of glucose oxidase upon zinc oxide nanowires In this case the sensitivity of the glucose sensor was determined to be 215 μA/(mmol/L·cm2), the linear range was 0-450 mmol/L, the low detection limit was 920 μmol/L and MichaelisMenten constant was 368 mmol/L The results not only benefit the batch production of the spirally hierarchical structurebased enzymatic electrodes, but also significantly improve the performances of the glucose sensors

KeywordsHierarchical structure; Surface morphology; Glucose biosensor; Cyclic voltammetry; Amperometric response