State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Ave, 210023, Nanjing, China.
Nat Commun. 2019 Aug 26;10(1):3849. doi: 10.1038/s41467-019-11816-3.
Measurement of electron transfer at single-molecule level is normally restricted by the detection limit of faraday current, currently in a picoampere to nanoampere range. Here we demonstrate a unique graphene-based electrochemical microscopy technique to make an advance in the detection limit. The optical signal of electron transfer arises from the Fermi level-tuned Rayleigh scattering of graphene, which is further enhanced by immobilized gold nanostars. Owing to the specific response to surface charged carriers, graphene-based electrochemical microscopy enables an attoampere-scale detection limit of faraday current at multiple individual gold nanoelectrodes simultaneously. Using the graphene-based electrochemical microscopy, we show the capability to quantitatively measure the attocoulomb-scale electron transfer in cytochrome c adsorbed at a single nanoelectrode. We anticipate the graphene-based electrochemical microscopy to be a potential electrochemical tool for in situ study of biological electron transfer process in organelles, for example the mitochondrial electron transfer, in consideration of the anti-interference ability to chemicals and organisms.
在单分子水平上测量电子转移通常受到法拉第电流检测极限的限制，目前处于皮安到纳安的范围。在这里，我们展示了一种独特的基于石墨烯的电化学显微镜技术，以提高检测极限。电子转移的光学信号源于石墨烯的费米能级调谐瑞利散射，通过固定的金纳米星进一步增强。由于对表面带电载流子的特定响应，基于石墨烯的电化学显微镜能够在多个单个金纳米电极上同时实现皮安级的法拉第电流检测极限。使用基于石墨烯的电化学显微镜，我们展示了在单个纳米电极上吸附的细胞色素 c 中定量测量阿特库仑级电子转移的能力。考虑到对化学物质和生物的抗干扰能力，我们预计基于石墨烯的电化学显微镜将成为细胞器内生物电子转移过程的原位研究的潜在电化学工具，例如线粒体电子转移。
