Label-free detection of single protein molecules and protein-protein interactions using synthetic nanopores.
Nanofabricated pores in 20 nm-thick silicon nitride membranes were used to probe various protein analytes as well as to perform an antigen-antibody binding assay. A two-compartment electrochemical cell was separated by a single nanopore, 28 nm in diameter. Adding proteins to one compartment caused current perturbations in the ion current flowing through the pore. These perturbations correlated with both the charge and the size of the protein or of a protein-protein complex. The potential of this nanotechnology for studying protein-protein interactions is highlighted with the sensitive detection of beta-human chorionic gonadotropin, a hormone and clinical biomarker of pregnancy, by monitoring in real time and at a molecular level the formation of a complex between hormones and antibodies in solution. In this form, the assay compared advantageously to immunoassays, with the important difference that labels, immobilization, or amplification steps were no longer needed. In conclusion, we present proof-of-principle that properties of proteins and their interactions can be investigated in solution using synthetic nanopores and that these interactions can be exploited to measure protein concentrations accurately.
Han
Anpan
A
Institute of Microtechnology, University of Neuchâtel, Rue Jaquet-Droz 1, P.O. Box 526, CH-2002 Neuchâtel, Switzerland.
Creus
Marc
M
Schürmann
Gregor
G
Linder
Vincent
V
Ward
Thomas R
TR
de Rooij
Nico F
NF
Staufer
Urs
U
D000818:Animals; D002417:Cattle; D002645:Chickens; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000379:methods*; D016062:Porosity; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*
D011506:Proteins