Electronic Supplementary Material
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Microbial glucose biosensors based on glassy carbon paste electrodes modified with
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Gluconobacter Oxydans and graphene oxide or graphene-platinum hybrid nanoparticles
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Sema Aslan, Ülkü Anik*
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a
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Mugla, Turkey
Mugla Sitki Kocman University, Faculty of Science, Chemistry Department, 48000-Kötekli,
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*Corresponding Author, Email: ulkuanik@yahoo.com; ulkuanik@gmail.com, Tel:+90-252-
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211-1503
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Optimizations of G. oxydans amount pH, working temperature and incubation time of
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developed microbial biosensor
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Optimum amount of G. oxydans (Fig. S1) was examined for 1.0 µL, 2.0 µL, 3.0 µL, 4.0 µL
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and 5.0 µL of cells. Cyclic voltammograms were obtained in the 50 mM pH 6.5 PB which
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contained 2.0 mM K3 [Fe (CN) 6] and 20 mM glucose, at a scan rate of 100 mV s1-. Then pH
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(Fig. S2A), working temperature (Fig. S2B) and incubation time (Fig. S2C) were optimized
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by using plain (without any nanocomposite) G.oxydans/ Graphene-Pt hybrid NPs /GCPE
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microbial biosensor. The electrode was renewed for every measurement. In order to define the
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optimum pH value we compared the cyclic voltammograms of microbial biosensor for pH:
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6.0, 6.5, 7.0, 7.5, and 8.0 respectively. Since best results was obtained at pH 6.5, further
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studies were conducted by utilizing this value. For finding optimum temperature,
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G.oxydans/GCPE whole cell biosensor was kept at different temperatures as 20, 25, 30 and 40
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°C and the 25 C provided best current value. The effect of incubation time of developed
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microbial biosensor was also examined. For this purpose, 3 µL of G. oxydans cell was added
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into paste and electrode was incubated in the 2 mM K3Fe (CN)
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containing 50 mM PB (pH 6.5) for 0, 10, 15 and 20 s. Maximum current was obtained at 10 s.
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and 20 mM glucose
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Fig. S1 Cyclic voltammograms and graphic (inset) of the G.oxydans amount effect on the
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developed microbial biosensor. Cyclic voltammograms were obtained in the 50 mM pH 6.5
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PB which contained 2.0 mM K3[Fe(CN)6] and 20 mM glucose, at a scan rate of 100 mV s-1.
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Fig. S2 Optimization graphics of ; A) pH, B) operational temperature and C) incubation time
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of G.oxydans/GCPE microbial biosensor.
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Table S1. Selectivity of the Graphene-Pt hybrid NP modified microbial biosensor in the
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presence of fructose and galactose as possible intereference agents.
Glucose
Fructose
Galactose
Current difference/%
Concentration / µM
Concentration / µM
Concentration / µM
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-
-
-
1
1
1
0.9
1
5
5
0.5
1
7
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1.4
1
10
10
0.5
1
100
100
13.6
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Table S2. Selectivity of the Graphene-Pt hybrid NP modified microbial biosensor in the
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presence of L-ascorbic acid and dopamine as possible intereference agents.
Glucose
L- ascorbic acid
Dopamine
Current difference/%
Concentration / µM
Concentration / µM
Concentration/ µM
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-
-
-
1
1
1
0.67
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2
2
2.29
1
5
5
5.17
1
10
10
7.45
1
50
50
9.10
1
100
100
12.07
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