title: Wide-range quantification of human thyroid-stimulating hormone using gold-nanopatterned single-molecule sandwich immunoassay chip.
abstract: We performed wide-range quantification of human thyroid-stimulating hormone (hTSH) using a gold nano-patterned sandwich immunoassay chip. Objective-type total internal reflection fluorescence microscopy (TIRFM) was used to detect hTSH at the single-molecule level. A gold spot with a diameter of 100 nm on a 10-mm square glass substrate was fabricated by electron beam nanolithography. When hTSH bound to antibodies conjugated to each 100-nm gold spot, there was an increase in the relative fluorescent intensity (RFI). The detection limit of this "TSH-nanoarray chip" was 360 zM (equivalent to five molecules), which demonstrated that a TSH-nanoarray chip could be used for detection at the single-molecule level. A linear response was observed over a wide dynamic range (from 360 zM to 36 pM, R=0.9812) without a fluorescence quenching effect. A significant enhancement in the sensitivity (~12,000-fold) was achieved with the 100-nm gold nano-patterned chip compared with results obtained using a traditional chemiluminescence immunoassay for the evaluation of TSH in human serum.
authors.affiliation: Department of Applied Chemistry, College of Applied Science, Kyung Hee University, Yongin-si, Gyeonggi-do 446-701, South Korea.
authors.forename: Seungah
authors.initials: S
authors.lastname: Lee
authors.forename: Seong Ho
authors.initials: SH
authors.lastname: Kang
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D005240:Feasibility Studies; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation*; D036103:Nanotechnology / Q000295:instrumentation*; D013972:Thyrotropin / Q000032:analysis*
chemical_list: D006046:Gold; D013972:Thyrotropin