Electronic Supporting Material
A fluorine-doped tin oxide electrode modified with gold nanoparticles for
electrochemiluminescent determination of hydrogen peroxide released by living cells
Man Li, Hongfang Gao, Xiaofei Wang, Yufeng Wang, Honglan Qi*, Chengxiao Zhang
Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of
Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, P.R. China
*Corresponding author. Tel: +86-29-81530726; Fax: +86-29-81530727. E-mail address:
[email protected] (H. L. Qi).
Figure S-1 A schematic diagram of ECL cell
Figure S-2 ECL intensity vs potential profiles obtained at ITO (a), FTO (b), AuNP-ITO
(c) and AuNP-FTO (d) in 0.1 M phosphate buffer solution (pH 7.4) containing 10 µM luminol
and 1 µM H2O2. Scan rate, 0.1 V⋅s-1.
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Figure S-3 Cyclic voltammograms obtained at bare gold electrode (a), AuNP-FTO (b), and
FTO (c) in 0.1 M H2SO4. Scan rate, 0.1 V⋅s-1.
Optimization of method
In order to obtain high sensitivity for the detection of H2O2, different parameters
including electrodeposited time, scan rate, initial and final potentials of linear sweep
voltammetry and concentration of luminol, were optimized. As shown in Figure S-4A, ECL
intensities increased obviously when electrodeposited time increased from 10 s to 25 s. The
ECL intensities reached the highest value at electrodeposited time of 25 s for 10 µM
luminol-1 µM H2O2 in 0.1 M phosphate buffer solution (pH 7.4). When ECL intensities
decreased after electrodeposited time increased up to 25 s. The decrease in ECL intensity may
be ascribed to the aggregation of gold nanoparticles on the surface of FTO [1]. Therefore, an
electrodeposited time of 25 s was chosen as optimized electrodeposited time.
It was found that the ECL intensities increased rapidly and reached the highest value at
scan rate of 0.1 V⋅s-1 for 10 µM luminol-1 µM H2O2 in 0.1 M phosphate buffer solution (pH
7.4, Figure S-4B). As the scan rate increases upto 0.1 V⋅s-1, ECL intensity decreased,
attributed to that less luminol intermediates was generated from the electrochemical oxidation
of luminol at fast scan rate [2]. Therefore, 0.1 V⋅s-1 was chosen as optimized scan rate.
Xu et al reported that anodic luminol ECL intensities are increased by setting suitable
negative initial potential and positive final potential in the absence of hydrogen peroxide [3].
Here, we examined whether the ECL behavior of luminol in the presence of hydrogen
peroxide can be affected by the initial potentials when fixed final potential at 0.9 V at
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AuNP-FTO. When the voltage was above +0.9 V, AuNP on FTO will be oxidized in 0.1 M
phosphate buffer solution (pH 7.4) (Figure S-5), suggesting that the maximum voltage for
AuNP-FTO is less than +0.9 V. It was found that both of the ECL intensities in the
absence/presence of hydrogen peroxide increased remarkably as the initial potentials
decreased from 0 to -0.7 V, attributed to the generation of more radical oxygen species, which
was similar with that reported by Xu [3]. The increased ECL intensity increased from 0 to -0.3
V and then kept constant after -0.3 V （Figure S-4C）. The ECL intensity employing an initial
potential of -0.4 V is about 10-fold higher than that of 0.0 V. A linear scan voltammetry in the
range -0.4 to +0.9 V with a scan rate of 0.1 V⋅s⁻¹, therefore, was chosen as optimized
conditions.
Figure S-4 Effect of electrodeposited time (A), scan rate (B) and initial potential of
linear sweep voltammetry (C) on the ECL intensity of 10 µM luminol-1 µM H2O2 in 0.1 M
phosphate buffer solution (pH 7.4) and effect of luminol concentration on the ECL intensity of
10 µM luminol-1 µM H2O2 in DMEM cell culture media (D)
The effect of luminol concentration on the increased ECL intensity was examined in
different media, including phosphate buffer solution and DMEM cell culture media. It was
found that the ECL intensity of luminol-H2O2 in DMEM cell culture media is much lower
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than that in 0.1 M phosphate buffer solution at the same condition. In order to assay of H2O2
released from living cells, the effect of luminol concentration on the ECL intensity was
optimized in DMEM cell culture media. For 1.0 μM hydrogen peroxide, the increased ECL
intensity reached the steady signal when the luminol concentration was above 100 μM
luminol in DMEM cell culture media (Figure S-4D). Therefore, 100 μM luminol was chosen
as optimized condition in DMEM cell culture media.
Figure S-5 Cyclic voltammograms obtained at bare FTO, AuNP-FTO, and gold electrode in
0.1 M phosphate buffer solution (pH 7.4). Scan rate, 0.1 V⋅s-1.
Figure S-6 ECL responses of 10 μM luminol -1 μM H2O2 in the presence of different
interfering substances, including 200 μM cholesterol, 25 μM UA, 25 μM AA, 10 μM LPO
and 50 μM TNF-α in 0.1 M phosphate buffer solution (pH 7.4). Scan rate, 0.1 V⋅s-1.
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Figure S-7 ECL intensity vs potential profiles of 100 µM luminol in DMEM (pH 7.4) at
AuNP-FTO, blank (a), RAW 264.7 macrophages cell secretions (b), RAW 264.7 macrophage
cell secretions stimulated with 1 µg⋅mL-1 PMA (c) Scan rate, 0.1 V⋅s-1.
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