Fig. 4
Comparison of bare electrode, graphite electrode and various graphene electrodes on electrochemical sensing. A (a) DPVs at the GC electrode for G (blue), A (orange), T (violet), and C (magenta), respectively; (b) DPVs at the graphite/GC electrode for G (blue), A (orange), T (violet), and C (magenta), respectively; (c) DPVs at the CR-GO/GC electrode for G (blue), A (orange), T (violet), and C (magenta), respectively; (d) DPVs for a mixture of G, A, T, and C at CR-GO/GC (green), graphite/GC (red), and GC electrodes (black); (e) DPVs for ssDNA at CR-GO/GC (green), graphite/GC (red), and GC electrodes (black); (f) DPVs for dsDNA at CR-GO/GC (green), graphite/GC (red), and GC electrodes (black). Concentrations for different species (a-f): G, A, T, C, ssDNA or dsDNA: 10 μg/mL. Electrolyte: 0.1 M pH 7.0 PBS. Reprinted with permission from [106]; Copyright 2009 American Chemical Society. B Histogram representing a comparison of impedimetric signals on GPO, GO, TR-GO, ER-GO and bare DEP electrode. Signal is represented as average Rct ratio ((Rct protein − Rct blank)/(Rct aptamer − Rct blank)). Error bars correspond to triplicate experiments. All measurements were performed with 10 mM K4[Fe(CN)6]/K3[Fe(CN)6] in Tris buffer solution (pH = 8.2) at room temperature. Reprinted from [107] with permission of The Royal Society of Chemistry. C The comparison of impedimetric response on graphene oxide, ER-GO and TR-GO recorded after hybridization with wild-type (grey), mutant (purple) and non-complementary (black) target DNA sequences. The signal is represented as Δratio = Δt/Δp, Δt = Rct, target-Rct, blank, Δp = Rct, probe-Rct, blank. Standard deviations correspond to triplicate experiments. Reprinted from [108] with permission of The Royal Society of Chemistry. D (a) Raman spectra of ERGO film at different CV cycles; (b) CV curves containing 30 µM isoniazid (INZ) at different reduction cycles, and (c) line chart of the relationship between reduction cycle number and peak current response towards INZ [118]