title: Tunable nanogap devices for ultra-sensitive electrochemical impedance biosensing.
abstract: A wealth of research has been available discussing nanogap devices for detecting very small quantities of biomolecules by observing their electrical behavior generally performed in dry conditions. We report that a gold nanogapped electrode with tunable gap length for ultra-sensitive detection of streptavidin based on electrochemical impedance technique. The gold nanogap is fabricated using simple monolayer film deposition and in-situ growth of gold nanoparticles in a traditional interdigitated array (IDA) microelectrode. The electrochemical impedance biosensor with a 25-nm nanogap is found to be ultra-sensitive to the specific binding of streptavidin to biotin. The binding of the streptavidin hinder the electron transfer between two electrodes, resulting in a large increase in electron-transfer resistance (Ret) for operating the impedance. A linear relation between the relative Ret and the logarithmic value of streptavidin concentration is observed in the concentration range from 1 pM (picomolar) to 100 nM (nanomolar). The lowest detectable concentration actually measured reaches 1 pM. We believe that such an electrochemical impedance nanogap biosensor provides a useful approach towards biomolecular detection that could be extended to a number of other systems.
authors.affiliation: Department of Chemistry, Wannan Medical College, Wuhu 241002, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Nanomaterials and Environmental Detection Laboratory, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, PR China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Department of Chemistry, Wannan Medical College, Wuhu 241002, PR China.
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Song
authors.affiliation: Department of Chemistry, Wannan Medical College, Wuhu 241002, PR China.
authors.forename: Qin-An
authors.initials: QA
authors.lastname: Huang
authors.affiliation: Department of Chemistry, Wannan Medical College, Wuhu 241002, PR China.
authors.forename: Si-Wei
authors.initials: SW
authors.lastname: Zhu
authors.affiliation: Nanomaterials and Environmental Detection Laboratory, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, PR China.
authors.forename: Xing-Jiu
authors.initials: XJ
authors.lastname: Huang
authors.affiliation: Department of Chemistry, Wannan Medical College, Wuhu 241002, PR China. Electronic address: yanwei_wnmc@hotmail.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wei
mesh_terms: D015374:Biosensing Techniques; D001710:Biotin / Q000378:metabolism; D017097:Electric Impedance; D004867:Equipment Design; D036103:Nanotechnology; D011485:Protein Binding; D019809:Streptavidin / Q000378:metabolism
chemical_list: D001710:Biotin; D019809:Streptavidin
keywords: Electrochemical impedance; Electron-transfer resistance; Streptavidin; Tunable nanogap devices; Ultra-sensitive