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Supplementary Material (ESI) for Chemical Communications
This journal is © The Royal Society of Chemistry 2002
“Alternate Assemblies of Thionine and Au-Nanoparticle on Amino Fuctionalized
Surface”
Wenlong Cheng , Junguang Jiang, Shaojun Dong* and Erkang Wang *
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry,
Chinese Academy of Sciences, Changchun, Jilin 130022, P. R. China. Fax: +86-431-5689711; email: ekwang@ns.ciac.jl.cn.
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distribution of Au-nanoparticle and thionine in the
superstructure.
S-1 and S-2 shows the typical AFM images of Aunanoparticle submonolayer and the assemblies with 9
bilayers of NPs:TH, respectively. The height value of the
colloidal Au nanoparticles given by AFM is about 10 nm
(APTMS aggregates have a height value of less than 5
nm). Also, it was observed that the large spacing existed
S-3 shows cyclic voltammograms of the as-prepared
between many isolated nanoparticles as shown in S-1 and
superstructure at different scan rates. The good linear
the spacing becomes smaller with increasing layer
relationship
numbers as shown in S-2. (lateral dimensions are different
demonstrates
surface-confined
redox
electrochemistry of electroactive species.
from S-1 due to different tips used, which results in
different tip convolutions) The analysis of the line scans
for the 9NPs:TH shows that the external surface of the
S-4
superstructure consists of a high surface density of
demonstrating
nanoparticles. It is noted that the alternate assemblies of
superstructure towards oxidation of NADH in 0.1 M
the Au-nanoparticle and thionine are different from the
KNO3 aqueous solution. The presence of 3 mM NADH
other LBL assemblies (these assemblies resulted in the
causes a large negative shift as shown in S-4c in the
sandwich-like layering of organic and inorganic strata or
anodic peak potential of about 390 mV in comparison
isolated islands [(a)Schrof, W.; Rozouvan, S.; Vankeuren,
with that of about 750 mV obtained at the bare gold disk
E.; Horn, D.; Schmitt, J.; Decher, G. Adv. Mater. 1998, 10,
electrode as shown in S-4a. The above fact demonstrates
338. (b)Gao, M.; Zhang, X.; Yang, B.; Li, F.; Shen, J.
that thionine immobilized into the superstructure exhibits
Thin Solid Films 1996, 284. (c)Mamedov, A. A.; Kotov,
similar electrocatalytic activity towards NADH like
N. A. Langmuir 2000, 16, 5530. (d) Decher, G. Sience
thionine monolayer [See: (a) reference 15 and (b) Chen, H.
1997, 277, 1232. (e) Decher, G.; Hong, J. D. Ber. Bunsen-
Y.; Zhou, D. M.; Xu, J. J.; Fang, H. Q. J. Electroanal.
Ges. Phys. Chem. Chem. Phys. 1991, 95, 1430.]). whereas
Chem. 1997, 422, 21.]. The well-behaved electrocatalysis
the present superstructure should be a uniform blend
behaviors of thionine immobilized into the superstructure
shows
the
typical
cyclic
the
electrocatalytic
voltammograms
activity
of
the
still demonstrates that the assemblies do not block
1
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electron transfer between the electrode and the electrolyte
solution, and the constructed nano-scale architecture
exhibits properties of metallic thin films, [Brown, K. R.;
Lyon, L. A.; Fox, A. P.; Reiss, B. D.; Natan, M. J. Chem.
15
Mater. 2000, 12, 314.] allowing them appropriate for
10
macroscopic electrochemical measurements.
5
attributed to pH effects, as demonstrated by previous
reports. [See: (a) reference 15 and (b) Chen, H. Y.; Zhou,
0
-5
D. M.; Xu, J. J.; Fang, H. Q. J. Electroanal. Chem. 1997,
-10
422, 21.]
-15
-15
Redox peak Current / A
Current / A
Three couples of redox peaks observed in S-4b are
-10
-5
R=0.9995
0
0
-20
0.0
0.1
0.2
0.3
0.4
200
0.5
400
600
E / mVs -1
800
0.6
1000
0.7
E / V vs Ag/Agcl
S-3 Cyclic voltammograms of 13 nanoparticle:thionine
bilayers modified gold electrode in 0.5 M H2SO4 at
different scan rates of 10, 20, 50, 100, 200, 300, 400, 500,
600, 700, 800, and 900 mV/s, respectively.
a
2.5
c
2.0
Current / A
1.5
S-1 Typical tapping-mode AFM image of first Aunanoparticle layer assembled on APTMS modified glass
slide.
1.0
b
0.5
0.0
-0.5
-1.0
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
E / V vs Ag/AgCl
S-4 Cyclic voltammograms at 50 mV/s of 13
nanoparticle:thionine bilayers modified gold electrode in
0.1 M KNO3 aqueous solution in the absence (b) and
presence (c) of 3 mM NADH. Dash line (a): Cyclic
voltammograms at 50 mV/s of clean bare gold electrode
in 0.1 M KNO3 and 3 mM NADH aqueous solution.
S-2 Typical tapping-mode AFM images of 9 bilayers of
nanoparticle:thionine (1.5 μ m2) on the glass surface.
Lateral dimensions of nanoparticles are distorted due to
the AFM tip convolution effect.
2