title: Label-free detection of protein-protein interactions using a calmodulin-modified nanowire transistor.
abstract: In this study, we describe a highly sensitive and reusable silicon nanowire field-effect transistor for the detection of protein-protein interactions. This reusable device was made possible by the reversible association of glutathione S-transferase-tagged calmodulin with a glutathione modified transistor. The calmodulin-modified transistor exhibited selective electrical responses to Ca2+ (> or = 1 microM) and purified cardiac troponin I (approximately 7 nM); the change in conductivity displayed a linear dependence on the concentration of troponin I in a range from 10 nM to 1 microM. These results are consistent with the previously reported concentration range in which the dissociation constant for the troponin I-calmodulin complex was determined. The minimum concentration of Ca2+ required to activate calmodulin was determined to be 1 microM. We have also successfully demonstrated that the N-type Ca2+ channels, expressed by cultured 293T cells, can be recognized specifically by the calmodulin-modified nanowire transistor. This sensitive nanowire transistor can serve as a high-throughput biosensor and can also substitute for immunoprecipitation methods used in the identification of interacting proteins.
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan.
authors.forename: Tsung-Wu
authors.initials: TW
authors.lastname: Lin
authors.forename: Po-Jen
authors.initials: PJ
authors.lastname: Hsieh
authors.forename: Chih-Lung
authors.initials: CL
authors.lastname: Lin
authors.forename: Yi-Ya
authors.initials: YY
authors.lastname: Fang
authors.forename: Jia-Xun
authors.initials: JX
authors.lastname: Yang
authors.forename: Chia-Chang
authors.initials: CC
authors.lastname: Tsai
authors.forename: Pei-Ling
authors.initials: PL
authors.lastname: Chiang
authors.forename: Chien-Yuan
authors.initials: CY
authors.lastname: Pan
authors.forename: Yit-Tsong
authors.initials: YT
authors.lastname: Chen
mesh_terms: D002147:Calmodulin / Q000378:metabolism*; D053770:Nanowires; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D011506:Proteins