Department of Molecular Sciences and Nanosystems, University Ca' Foscari of Venice, Venice, Italy.
Anal Bioanal Chem. 2013 Jan;405(2-3):995-1005. doi: 10.1007/s00216-012-6354-3. Epub 2012 Sep 6.
A new method to increase the active area (A(act)) of nanoelectrode ensembles (NEEs) is described. To this aim, gold nanoparticles (AuNPs) are immobilized onto the surface of NEEs using cysteamine as a cross-linker able to bind the AuNPs to the heads of the nanoelectrodes to obtain the so-called AuNPs-NEEs. The analysis of the cyclic voltammograms recorded in pure supporting electrolyte showed that the presence of the nanoparticles reflects in an, approximately, ten-times increase in the electrochemically active area of the ensemble. The measurement of the amount of electroactive polyoxometalates, which can be adsorbed on the gold surface of NEEs vs. AuNPs-NEEs, confirmed a significant increase of active area for the latter. These evidences indicate that there is a good electronic connection between the AuNPs and the underlying nanoelectrodes. The possibility to exploit AuNPs-NEEs for biosensing application was tested for the case of DNA-hybridization detection. After immobilization on the gold surface of AuNPs-NEEs of a thiolated single-stranded DNA, the hybridization with complementary sequences labeled with glucose oxidase (GOx) was performed. The detection of the hybridization was achieved by adding to the electrolyte solution the GOx substrate (i.e., glucose) and a suitable redox mediator, namely the (ferrocenylmethyl) trimethylammonium (FA(+)) cation; when the hybridization occurs, an electrocatalytic increase of the oxidation current of FA(+) is recorded. Comparison of electrocatalytic current recorded at DNA modified NEEs and AuNPs-NEEs indicate, for the latter, a significant increase in sensitivity in the detection of the DNA-hybridization event.
描述了一种增加纳米电极组件（NEE）有效面积（A(act)）的新方法。为此，使用半胱胺作为交联剂将金纳米粒子（AuNPs）固定在 NEE 的表面上，该交联剂能够将 AuNPs 结合到纳米电极的头部，从而获得所谓的 AuNPs-NEEs。在纯支持电解质中记录的循环伏安法分析表明，纳米粒子的存在反映了集合体的电化学活性面积大约增加了十倍。测量可以吸附在 NEEs 与 AuNPs-NEEs 的金表面上的电活性多金属氧酸盐的量，证实了后者的活性面积有了显著增加。这些证据表明 AuNPs 和底层纳米电极之间存在良好的电子连接。AuNPs-NEEs 用于生物传感应用的可能性已经过测试，例如 DNA 杂交检测。在 AuNPs-NEEs 的金表面上固定硫醇化单链 DNA 后，用标记有葡萄糖氧化酶（GOx）的互补序列进行杂交。通过向电解质溶液中添加 GOx 底物（即葡萄糖）和合适的氧化还原介质，即（二茂铁基）三甲铵（FA(+)）阳离子，来检测杂交。当发生杂交时，记录到 FA(+) 的氧化电流的电催化增加。在修饰有 DNA 的 NEEs 和 AuNPs-NEEs 上记录的电化学催化电流的比较表明，对于后者，在检测 DNA 杂交事件方面灵敏度有了显著提高。
