 The first SPR immunoassay was proposed in 1983 by Liedberg, Nylander, and Lundström, then of the Linköping Institute of Technology (Sweden).They adsorbed
human IgG onto a 600-angstrom silver film, and used the assay to detect anti-human IgG in water solution.Unlike many other immunoassays, such as ELISA, an SPR immunoassay is "label free" in that a label molecule is not required for detection of the analyte.