title: Development of a single-step immunoassay microdevice based on a graphene oxide-containing hydrogel possessing fluorescence quenching and size separation functions.
abstract: An immunoassay, which is an indispensable analytical method both in biological research and in medical fields was successfully integrated into a "single-step" by developing a microdevice composed of a graphene oxide (GO)-containing hydrogel and a poly (dimethylsiloxane) (PDMS) microchannel array with a polyethylene glycol (PEG) coating containing a fluorescently-labelled antibody. Here we used 2-hydroxyethylmethacrylate (HEMA) as a monomer that is easily, and homogeneously, mixed with GO to synthesize the hydrogel. The fluorescence quenching and size separation functions were then optimized by controlling the ratios of HEMA and GO. Free fluorescently-labelled antibody was successfully separated from the immunoreaction mixture by the hydrogel network structure, and the fluorescence was subsequently quenched by GO. In comparison to the previously reported immunoassay system using GO, the present system achieved a very high fluorescence resonance energy transfer (FRET) efficiency (∼90%), due to the use of direct adsorption of the fluorescently-labelled antibody to the GO surface; in contrast, the former reported method relied on indirect adsorption of the fluorescently-labelled antibody via immunocomplex formation at the GO surface. Finally, the single-step immunoassay microdevice was made by combining the developed hydrogel and the PDMS microchannel with a coating containing the fluorescently-labelled antibody, and successfully applied for the single-step analysis of IgM levels in diluted human serum by simple introduction of the sample via capillary action.
authors.affiliation: Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho Nakaku, Sakai City, Osaka, 599-8531, Japan. hisamoto@chem.osakafu-u.ac.jp.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Shirai
authors.affiliation: Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho Nakaku, Sakai City, Osaka, 599-8531, Japan. hisamoto@chem.osakafu-u.ac.jp.
authors.forename: Kaho
authors.initials: K
authors.lastname: Nakashima
authors.affiliation: Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho Nakaku, Sakai City, Osaka, 599-8531, Japan. hisamoto@chem.osakafu-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sueyoshi
authors.affiliation: Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho Nakaku, Sakai City, Osaka, 599-8531, Japan. hisamoto@chem.osakafu-u.ac.jp.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Endo
authors.affiliation: Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho Nakaku, Sakai City, Osaka, 599-8531, Japan. hisamoto@chem.osakafu-u.ac.jp.
authors.forename: Hideaki
authors.identifier: http://orcid.org/0000-0003-1067-4116
authors.initials: H
authors.lastname: Hisamoto
mesh_terms: D000906:Antibodies / Q000737:chemistry*; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer; D006108:Graphite; D006801:Humans; D020100:Hydrogels; D007118:Immunoassay; D007075:Immunoglobulin M / Q000097:blood; D010087:Oxides; D011092:Polyethylene Glycols
chemical_list: D000906:Antibodies; D020100:Hydrogels; D007075:Immunoglobulin M; D010087:Oxides; D011092:Polyethylene Glycols; D006108:Graphite