title: Nanohole-based surface plasmon resonance instruments with improved spectral resolution quantify a broad range of antibody-ligand binding kinetics.
abstract: We demonstrate an affordable low-noise surface plasmon resonance (SPR) instrument based on extraordinary optical transmission (EOT) in metallic nanohole arrays and quantify a broad range of antibody-ligand binding kinetics with equilibrium dissociation constants ranging from 200 pM to 40 nM. This nanohole-based SPR instrument is straightforward to construct, align, and operate, since it is built around a standard microscope and a portable fiber-optic spectrometer. The measured refractive index resolution of this platform is 3.1 × 10(-6) without on-chip cooling, which is among the lowest reported for SPR sensors based on EOT. This is accomplished via rapid full-spectrum acquisition in 10 ms followed by frame averaging of the EOT spectra, which is made possible by the production of template-stripped gold nanohole arrays with homogeneous optical properties over centimeter-sized areas. Sequential SPR measurements are performed using a 12-channel microfluidic flow cell after optimizing surface modification protocols and antibody injection conditions to minimize mass-transport artifacts. The immobilization of a model ligand, the protective antigen of anthrax on the gold surface, is monitored in real-time with a signal-to-noise ratio of ~860. Subsequently, real-time binding kinetic curves were measured quantitatively between the antigen and a panel of small, 25 kDa single-chain antibodies at concentrations down to 1 nM. These results indicate that nanohole-based SPR instruments have potential for quantitative antibody screening and as a general-purpose platform for integrating SPR sensors with other bioanalytical tools.
authors.affiliation: Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Hyungsoon
authors.initials: H
authors.lastname: Im
authors.forename: Jamie N
authors.initials: JN
authors.lastname: Sutherland
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Maynard
authors.forename: Sang-Hyun
authors.initials: SH
authors.lastname: Oh
mesh_terms: D000941:Antigens / Q000378:metabolism*; D015374:Biosensing Techniques; D006046:Gold / Q000737:chemistry; D007700:Kinetics; D046228:Microarray Analysis; D049329:Nanostructures / Q000737:chemistry*; D059629:Signal-To-Noise Ratio; D057127:Single-Chain Antibodies / Q000378:metabolism*; D020349:Surface Plasmon Resonance / Q000295:instrumentation* / Q000379:methods*
chemical_list: D000941:Antigens; D057127:Single-Chain Antibodies; D006046:Gold