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Acknowledgements Fig. 6. CVs recorded at a nanostructured gold electrode in a solution containing 0.6 mM cyt c and 5mM 4,4’-bipyridyl in 0.01 M PBS at a sweep rate of 20, 50, 100, 200 and 300 mVs-!.

Figure 6 Acknowledgements Fig. 6. CVs recorded at a nanostructured gold electrode in a solution containing 0.6 mM cyt c and 5mM 4,4’-bipyridyl in 0.01 M PBS at a sweep rate of 20, 50, 100, 200 and 300 mVs-!.

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Fig. 2. Electrochemical experiments carried out at unmodified gold (grey) and nanostructured gold (black), CV in (a) 0.1 M PBS, (b) CV for an activated gold electrode (—1.80\ for 10 min) in 0.1 M PBS, (c) 1 mM dopamine in 0.1 M PBS, obtained at 50 mVs~! and (d) Nyquist plots obtained in 5 mM Fe(CN).3~/4~ in 0.1 M PBS. Cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) experiments were conducted with a CH Instruments, Model CHI760C poten- tiostat using a 3-electrode configuration and employing a 2mm diameter gold working electrode (BAS), a graphite rod (6 mm diam- eter, Johnson Matthey Ultra ‘F’ purity grade) counter electrode and a Ag/AgCl (3M KCl) reference electrode. Prior to all electrochem- ical experiments, the electrolyte was degassed using high purity nitrogen. EIS experiments were performed at the formal redox potential of Fe(CN),2~/4- at an amplitude of 5 mV over a frequency range of 0.1-10° Hz. The electrochemically active surface area of the electrodes was determined by calculating the charge associ- ated with the reduction of the monolayer oxide peak at 0.93 V and using a value of 400 uCcm~? of gold [29]. The pH of the solution was measured with a pH meter from Hanna Instruments (pH211). All experiments were conducted at 20+2°C. Scanning electron microscopy (SEM) measurements were performed on a FEI Nova Nano instrument using a custom built electrode holder. Prior to SEM imaging, samples were thoroughly rinsed with Milli-Q water and dried under a flow of nitrogen.
Fig. 2. Electrochemical experiments carried out at unmodified gold (grey) and nanostructured gold (black), CV in (a) 0.1 M PBS, (b) CV for an activated gold electrode (—1.80\ for 10 min) in 0.1 M PBS, (c) 1 mM dopamine in 0.1 M PBS, obtained at 50 mVs~! and (d) Nyquist plots obtained in 5 mM Fe(CN).3~/4~ in 0.1 M PBS. Cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) experiments were conducted with a CH Instruments, Model CHI760C poten- tiostat using a 3-electrode configuration and employing a 2mm diameter gold working electrode (BAS), a graphite rod (6 mm diam- eter, Johnson Matthey Ultra ‘F’ purity grade) counter electrode and a Ag/AgCl (3M KCl) reference electrode. Prior to all electrochem- ical experiments, the electrolyte was degassed using high purity nitrogen. EIS experiments were performed at the formal redox potential of Fe(CN),2~/4- at an amplitude of 5 mV over a frequency range of 0.1-10° Hz. The electrochemically active surface area of the electrodes was determined by calculating the charge associ- ated with the reduction of the monolayer oxide peak at 0.93 V and using a value of 400 uCcm~? of gold [29]. The pH of the solution was measured with a pH meter from Hanna Instruments (pH211). All experiments were conducted at 20+2°C. Scanning electron microscopy (SEM) measurements were performed on a FEI Nova Nano instrument using a custom built electrode holder. Prior to SEM imaging, samples were thoroughly rinsed with Milli-Q water and dried under a flow of nitrogen.
Fig. 1. SEM image of nanostructured gold electrodeposited at 0.05 V for 600s from 6.9mM HAuCl, and 0.5 mM Pb(CH3COO)>.
Fig. 1. SEM image of nanostructured gold electrodeposited at 0.05 V for 600s from 6.9mM HAuCl, and 0.5 mM Pb(CH3COO)>.
Fig. 3. CVs recorded in a solution containing 1 mM ascorbic acid (black) and 1 mM dopamine (grey) in 0.1 M PBS at a scan rate of 50 mVs~! for (a) nanostructured gold and (b) unmodified gold. (c) DPVs recorded in 1 mM ascorbic acid with dopamine at concentrations of 0-90 .M (104M increments) in 0.1M PBS at a nanostruc- tured gold electrode where the inset shows a plot of peak current versus dopamine concentration.
Fig. 3. CVs recorded in a solution containing 1 mM ascorbic acid (black) and 1 mM dopamine (grey) in 0.1 M PBS at a scan rate of 50 mVs~! for (a) nanostructured gold and (b) unmodified gold. (c) DPVs recorded in 1 mM ascorbic acid with dopamine at concentrations of 0-90 .M (104M increments) in 0.1M PBS at a nanostruc- tured gold electrode where the inset shows a plot of peak current versus dopamine concentration.
Fig. 4. DPVs recorded in 1 mM ascorbic acid with dopamine at concentrations of 0-100 iM (10 uM increments) in 0.1 M PBS obtained at Nafion coated (a) nanostructured gold electrode and (b) an unmodified gold electrode, (c) plot of peak current versus dopamine concentration at a nanostructured (@) and unmodified (™) gold electrode, (d) DPVs recorded on a Nafion coated nanostructured gold electrode in 0.1 M PBS containing 0.05 mM dopamine (black), with the addition of 0.2 mM uric acid (dashed) and further addition of 1 mM AA (grey).
Fig. 4. DPVs recorded in 1 mM ascorbic acid with dopamine at concentrations of 0-100 iM (10 uM increments) in 0.1 M PBS obtained at Nafion coated (a) nanostructured gold electrode and (b) an unmodified gold electrode, (c) plot of peak current versus dopamine concentration at a nanostructured (@) and unmodified (™) gold electrode, (d) DPVs recorded on a Nafion coated nanostructured gold electrode in 0.1 M PBS containing 0.05 mM dopamine (black), with the addition of 0.2 mM uric acid (dashed) and further addition of 1 mM AA (grey).
Fig. 5. CVs recorded at a nanostructured gold electrode modified with (a) cysteine in 1M KOH at a sweep rate of 50mVs~! and (b) cysteine/cytochrome c in 0.01 M PBS at sweep rates of 20, 50, 100, 200 and 300 mVs~!, (c) plot of peak current versus sweep rate for the anodic (@) and cathodic (™) processes at the lower potential, (d) CVs recorded at reduced potential limits.
Fig. 5. CVs recorded at a nanostructured gold electrode modified with (a) cysteine in 1M KOH at a sweep rate of 50mVs~! and (b) cysteine/cytochrome c in 0.01 M PBS at sweep rates of 20, 50, 100, 200 and 300 mVs~!, (c) plot of peak current versus sweep rate for the anodic (@) and cathodic (™) processes at the lower potential, (d) CVs recorded at reduced potential limits.
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