Key laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an 710062, China.
Biosens Bioelectron. 2013 May 15;43:205-10. doi: 10.1016/j.bios.2012.12.016. Epub 2012 Dec 23.
We prepared a new positively-charged gold nanoparticle ((+)AuNPs)-single-walled carbon nanotubes (SWNTs) nanohybrids. The results showed that small (+)AuNPs dispersed uniformly on the surface of SWNTs. Importantly the resulting nanohybrids exhibited fascinating peroxidase-like activity, which can catalyze oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 to develop a blue color in aqueous solution. Furthermore, single-stranded DNA (ss-DNA) can resist salt-induced (+)AuNPs-SWNTs nanohybrids aggregation, whereas double-stranded DNA (ds-DNA) can not inhibit salt-induced nanohybrids aggregation. Based on these unique properties of the (+)AuNPs-SWNTs nanohybrids, we developed a label-free colorimetric method for DNA hybridization detection. The response to target DNA concentration was linear in the range of 0.025-0.5μM with a detection limit of 2nM (3σ). Based on the specific recognition of aptamer, the method can be extended to detect non-nucleic acid targets such as cocaine. The present limit of detection for cocaine is 2nM. The method offers the advantages of simple, cheap, rapid and sensitive.
我们制备了一种新型带正电的金纳米粒子（+AuNPs）-单壁碳纳米管（SWNTs）纳米杂化物。结果表明，小尺寸的（+）AuNPs 均匀分散在 SWNTs 表面。重要的是，所得到的纳米杂化物表现出迷人的过氧化物酶样活性，可催化过氧化物酶底物 3,3,5,5-四甲基联苯胺（TMB）在 H2O2 存在下被氧化，在水溶液中产生蓝色。此外，单链 DNA（ss-DNA）可以抵抗盐诱导的（+）AuNPs-SWNTs 纳米杂化物聚集，而双链 DNA（ds-DNA）不能抑制盐诱导的纳米杂化物聚集。基于（+）AuNPs-SWNTs 纳米杂化物的这些独特性质，我们开发了一种无标记比色法用于 DNA 杂交检测。对靶 DNA 浓度的响应在 0.025-0.5μM 范围内呈线性，检测限为 2nM（3σ）。基于适体的特异性识别，该方法可扩展用于检测非核酸靶标，如可卡因。可卡因的检测限目前为 2nM。该方法具有简单、廉价、快速和灵敏的优点。
