title: Graphene-modified interdigitated array electrode: fabrication, characterization, and electrochemical immunoassay application.
abstract: We have developed a new procedure for fabricating interdigitated array gold electrodes (Au-IDA) modified with reduced graphene oxide (rGO).  In this procedure, we coated the gold surface of the micrometer order electrodes with graphene oxide (GO) prior to the reduction and the lift-off processes to avoid short-circuiting the pair of electrodes by conductive rGO flakes after the reduction.  We then studied the basic electrochemical activity of the prepared electrodes, rGO/Au-IDA, mainly on p-aminophenol (pAP), because pAP is a good probe for an electrochemical immunoassay.  The voltammograms showed that denser rGO provides better electrode reactivity for pAP.  We confirmed that redox cycling between the anode and cathode at the rGO/Au-IDA was established, which yields more sensitive detection than with a single electrode.  As one application of the electrochemical immunoassay using the rGO/Au-IDA, we demonstrated the quantitative detection of cortisol, a stress marker, at levels found in human saliva.
authors.affiliation: NTT Microsystem Integration Laboratories, NTT Corporation, Atsugi, Kanagawa, Japan. ueno.yuko@lab.ntt.co.jp
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ueno
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Furukawa
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Hayashi
authors.forename: Makoto
authors.initials: M
authors.lastname: Takamura
authors.forename: Hiroki
authors.initials: H
authors.lastname: Hibino
authors.forename: Emi
authors.initials: E
authors.lastname: Tamechika
mesh_terms: D000627:Aminophenols / Q000737:chemistry; D015415:Biomarkers / Q000032:analysis; D002138:Calibration; D055664:Electrochemical Techniques / Q000295:instrumentation* / Q000379:methods; D004566:Electrodes; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation / Q000379:methods; D006046:Gold / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods; D010084:Oxidation-Reduction; D012463:Saliva / Q000737:chemistry; D012680:Sensitivity and Specificity; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
chemical_list: D000627:Aminophenols; D015415:Biomarkers; D006046:Gold; D006108:Graphite; C026729:4-aminophenol; D006854:Hydrocortisone