Improved localized surface plasmon resonance immunoassay with gold bipyramid substrates.
Gold nanoparticles bound to substrates exhibit localized surface plasmon resonance (LSPR) in their optical extinction spectra at visible and near-infrared wavelengths. The LSPR wavelength is sensitive to the surrounding refractive index, enabling a simple, label-free immunoassay when capture antibodies are bound to the nanoparticles. Gold bipyramids are nanoparticles with a penta-twinned crystal structure, which have a sharp LSPR because of their high monodispersity. Bipyramid substrates were found to have a refractive index sensitivity ranging from 288 to 381 nm/RIU (-0.62 to -0.68 eV/RIU), increasing with the nanoparticle size and aspect ratio. In an immunoassay, the bipyramid substrates yielded higher sensitivity than nanorods and nanospheres. An immunoassay sensitivity constant which depends on both the optical properties of the nanoparticle and conjugation chemistry was found to be K(LSPR) = 0.01 nm x microm(2) for gold bipyramids.
Department of Chemistry, Rice University, Houston, Texas 77005-1827, USA.
Seunghyun
S
Lee
Kathryn M
KM
Mayer
Jason H
JH
Hafner
D000818:Animals; D000906:Antibodies / Q000032:analysis; D000888:Antibodies, Anti-Idiotypic / Q000032:analysis / Q000276:immunology; D055910:Antibodies, Immobilized / Q000276:immunology; D006041:Goats; D006046:Gold / Q000737:chemistry*; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000276:immunology; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry; D011817:Rabbits; D012031:Refractometry; D012680:Sensitivity and Specificity; D020349:Surface Plasmon Resonance / Q000379:methods*
D000906:Antibodies; D000888:Antibodies, Anti-Idiotypic; D055910:Antibodies, Immobilized; D007074:Immunoglobulin G; D011092:Polyethylene Glycols; D006046:Gold