title: Edge promoted ultrasensitive electrochemical detection of organic bio-molecules on epitaxial graphene nanowalls.
abstract: We report the simultaneous electrochemical detection of dopamine (DA), uric acid (UA) and ascorbic acid (AA) on three dimensional (3D) unmodified 'as-grown' epitaxial graphene nanowall arrays (EGNWs). The 3D few layer EGNWs, unlike the 2D planar graphene, offers an abundance of vertically oriented nano-graphitic-edges that exhibit fast electron-transfer kinetics and high electroactive surface area to geometrical area (EAA/GA≈134%), as evident from the Fe(CN)6(3-/4-) redox kinetic study. The hexagonal sp(2)-C domains, on the basal plane of the EGNWs, facilitate efficient adsorption via spontaneous π-π interaction with the aromatic rings in DA and UA. Such affinity together with the fast electron kinetics enables simultaneous and unambiguous identification of individual AA, DA and UA from their mixture. The unique edge dominant EGNWs result in an unprecedented low limit of detection (experimental) of 0.033 nM and highest sensitivity of 476.2 µA/µM/cm(2), for UA, which are orders of magnitude higher than comparable existing reports. A reaction kinetics based modeling of the edge-oriented 3D EGNW system is proposed to illustrate the superior electro-activity for bio-sensing applications.
authors: Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan.
authors: Pradip
authors: P
authors: Kumar Roy
authors: Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan; Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan.
authors: Abhijit
authors: A
authors: Ganguly
authors: Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
authors: Wei-Hsun
authors: WH
authors: Yang
authors: Nano Device Materials Characterization Division, National Nano Device Laboratories, Hsinchu, Taiwan.
authors: Chien-Ting
authors: CT
authors: Wu
authors: Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung, Taiwan.
authors: Jih-Shang
authors: JS
authors: Hwang
authors: Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
authors: Yian
authors: Y
authors: Tai
authors: Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan; Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan. Electronic address: chenkh@pub.iams.sinica.edu.tw.
authors: Kuei-Hsien
authors: KH
authors: Chen
authors: Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan. Electronic address: chenlc@ntu.edu.tw.
authors: Li-Chyong
authors: LC
authors: Chen
authors: Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan; Biophotonics and Molecular Imaging Research Centre, National Yang Ming University, Taipei, Taiwan. Electronic address: sur@ym.edu.tw.
authors: Surojit
authors: S
authors: Chattopadhyay
mesh_terms: D001704:Biopolymers / Q000032:analysis* / Q000737:chemistry; D045424:Complex Mixtures / Q000032:analysis / Q000737:chemistry; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000737:chemistry*; D007118:Immunoassay / Q000295:instrumentation*; D008832:Microchemistry / Q000295:instrumentation; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001704:Biopolymers; D045424:Complex Mixtures; D009930:Organic Chemicals; D006108:Graphite
keywords: Dopamine; Electrochemical detection; Limit of detection; Reaction kinetics; Sensitivity; Three dimensional (3D) epitaxial graphene