Mawson Institute, University of South Australia, Australia.
School of Chemical and Physical Sciences, Flinders University, Australia.
Biosens Bioelectron. 2015 May 15;67:642-8. doi: 10.1016/j.bios.2014.09.089. Epub 2014 Oct 5.
The use of carbon nanotubes (CNTs) as building blocks in the design of electrochemical biosensors has been attracting attention over the last few years, mainly due to their high electrical conductivity and large surface area. Here, we present two approaches based on tailored single-walled CNTs (SWCNTs) architectures to develop immunosensors for the bacteriophage MS2, a virus often detected in sewage-impacted water supplies. In the first approach, SWCNTs were used in the bottom-up design of sensors as antibody immobilization support. Carboxy-functionalised SWCNTs were covalently tethered onto gold electrodes via carbodiimide coupling to cysteamine-modified gold electrodes. These SWCNTs were hydrazide functionalized by electrochemical grafting of diazonium salts. Site-oriented immobilization of antibodies was then carried out through hydrazone bond formation. Results showed microarray electrode behavior, greatly improving the signal-to-noise ratio. Excellent sensitivity and limit of detection (9.3 pfu/mL and 9.8 pfu/mL in buffer and in river water, respectively) were achieved, due to the combination of the SWCNTs' ability to promote electron transfer reactions with electroactive species at low overpotentials and their high surface-to-volume ratio providing a favorable environment to immobilize biomolecules. In the second approach, SWCNTs were decorated with iron oxide nanoparticles. Diazonium salts were electrochemically grafted on iron-oxide-nanoparticle-decorated SWCNTs to functionalize them with hydrazide groups that facilitate site-directed immobilization of antibodies via hydrazone coupling. These magnetic immunocarriers facilitated MS2 separation and concentration on an electrode surface. This approach minimized non-specific adsorptions and matrix effects and allowed low limits of detection (12 pfu/mL and 39 pfu/mL in buffer and in river water, respectively) that could be further decreased by incubating the magnetic immunocarriers with larger volumes of sample. Significantly, both approaches permitted the detection of MS2 to levels regularly encountered in sewage-impacted environments.
近年来，将碳纳米管（CNTs）用作电化学生物传感器设计中的构建块引起了人们的关注，主要是因为它们具有高导电性和大表面积。在这里，我们提出了两种基于定制单壁 CNTs（SWCNTs）结构的方法来开发针对噬菌体 MS2 的免疫传感器，噬菌体 MS2 是一种经常在受污水影响的供水系统中检测到的病毒。在第一种方法中，SWCNTs 被用作传感器的自下而上设计中的抗体固定支持物。通过碳二亚胺偶联将羧基功能化的 SWCNTs 共价连接到巯基修饰的金电极上。通过电化学接枝叠氮盐对这些 SWCNTs 进行了酰肼功能化。然后通过形成腙键进行抗体的定向固定。结果显示出微阵列电极行为，大大提高了信噪比。由于 SWCNTs 具有在低过电势下促进电子转移反应与电活性物质的能力，并且具有高的表面积与体积比，为固定生物分子提供了有利的环境，因此实现了出色的灵敏度和检测限（在缓冲液中和河水中分别为 9.3 pfu/mL 和 9.8 pfu/mL）。在第二种方法中，SWCNTs 用氧化铁纳米粒子修饰。通过电化学接枝在氧化铁纳米粒子修饰的 SWCNTs 上接枝叠氮盐，使它们具有酰肼基团，通过腙键偶联可以将抗体进行定向固定。这些磁性免疫载体有助于 MS2 在电极表面的分离和浓缩。这种方法最小化了非特异性吸附和基质效应，并允许检测限达到较低水平（在缓冲液中和河水中分别为 12 pfu/mL 和 39 pfu/mL），通过将磁性免疫载体与更大体积的样品孵育可以进一步降低检测限。重要的是，这两种方法都可以检测到污水影响环境中经常遇到的 MS2 水平。
