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Application of the Screen Printed Planar Electrode Modified with Ruthenium Hexacyanoferrate to Glucose Biosensor
Kuo-Hsiang Liao(廖國翔) , Chung-Min Lien(連崇閔), Hau Lin(林浩)
Department of Chemical and Materials Engineering, Southern Taiwan University
Abstract：
The glucose and oxygen can be catalyzed by the glucose oxidase to produce the gluconic acid and hydrogen peroxide. Because the ruthenium hexacyanoferrate(Ⅱ) possesses the excellent conductivity and catalytic characteristic, it can be
used to elevate the responding current for detection of reduction of hydrogen peroxide. A study was conducted to use the ruthenium hexacyanoferrate(Ⅱ) to modify the screen printed planar electrode which was used as the working electrode
to detect the responding current of reduction of hydrogen peroxide in the PBS buffer solution( pH = 7.4 )and the sensitivity of detection of hydrogen peroxide was determined from the responding current and consequently, the concentration of
the glucose could be determined. The results showed that the responding current for the carbon paste electrode modified with the ruthenium hexacyanoferrate(Ⅱ) was elevated significantly. At 30℃ , -0.2V operating potential, and in 0.05 M
PBS buffer solution( pH = 7.4 ), when the screen printed planar electrode was modified with the ruthenium hexacyanoferrate(Ⅱ) [ruthenium hexacyanoferrate(Ⅱ) : graphite carbon powders = 3 : 7 ( weight ratio )] , the detection limit was 0.02
mM H2O2 , the linear range was 0.02～0.96 mM H2O2, R2=0.917, and the sensitivity was 28.77μA/cm2ּmM H2O2 . For the screen printed planar glucose sensor, the detection limit was 0.02 mM C6H12O6 , the linear range was 0.02~2.24 mM
C6H12O6 (R2=0.9983), and the sensitivity was 12.19 µA/cm2．mM C6H12O6.
Results and Discussion：
Introduction :
At present, there is no effective method and medicine to cure the diabetes. The concentration
(
of the blood sugar for diabetic can only be controlled by insulin. The traditional routine
examination must be performed by the medical examiners in the hospitals and the examination
)
usually requires using the expensive instruments. Also this kind of examination requires high
expense and professional manipulation. Therefore, developing a rapid, convenient, and
economical glucose biosensor for detecting the glucose is an important research subject.
( )
Chemicals and Reagents
Ruthenium（Ⅲ）Chloride Hydrate(RuCl3); Potassium Hexacyanoferrate(II)(K4[Fe(CN)6] .
3H2O) ;Hydrogen Peroxide (H2O2); Glucose Oxidase(EC 1.1.3.4, Type X-S: From Aspergillus Niger,
50000 units/mg); Graphite Carbon Powder; Carbon Paste; Cyclohexanone(C6H10O); Nafion;
Potassium Dihydrogenphosphate(KH2PO4); Potassium Chloride (KCl); D(+)-Glucose
Monohydrate(C6H12O6).
Fig 1. CV graphs for (A) carbon paste electrode
modified with ruthenium hexacyanoferrate(Ⅱ)
( the range of scanning potential: -0.8～+0.8 V)
(B) unmodified carbon paste electrode( the
range of scanning potential: -0.6～+0.6 V)
Fig. 2 TB graphs of the carbon paste electrodes with
different ratios of ruthenium hexacyanoferrate(Ⅱ) to
graphite carbon powders; the ruthenium
hexacyanoferrate(Ⅱ) : graphite carbon powders
were〔(A) 0:10(unmodified carbon paste electrode)
(B) 1:9 (C) 2:8 (D) 3:7 (E) 4:6 (F) 5:5〕
Equipment
Electrochemical Analyzer (CHI 614A, CH Instruments, Inc) was used to measure the activity of
electrode by Cyclic Voltammetry ( CV ) and Time Base ( TB ) mode ; pH meter (Metrohm 731);
Constant Temperature Thermal Bath (Wisdom BC-2DT 10L); Oven (DENG YNG) ; Electric
Stirrer (Fargo); Carbon Paste Electrode and Screen Printed Planar Electrode were used as the
working electrodes, Coiled Platinum Wire was used as the counter electrode and Ag / AgCl was
used as the reference electrode.
Preparation of the Carbon Paste Electrode
Take one section of 7 cm electric wire with 0.05 cm inside diameter. After depriving the coating
0.5 cm length from both ends, the nake-ended wire was washed, dried and ready for use. Then the
ruthenium hexacyanoferrate(Ⅱ) powders, graphite carbon powders and carbon paste were mixed
with the appropriate ratio (ruthenium hexacyanoferrate(Ⅱ) : graphite carbon powders : carbon
paste = 0.3 : 0.7 : 1). After the mixing was complete, the mixture was evenly coated on the nakeended electric wire and dried in the oven and then we obtained the carbon paste electrode.
Fig. 3 The TB graphs of screen printed planar
electrodes for detection of H2O2
(ruthenium
hexacyanoferrate(Ⅱ): graphite carbon powders = 3 :
7); At 30 ℃; the operating potential = –0.2 V; in 0.1
M KCl of 5 mL 0.05 M PBS buffer solution ( pH=7.4 );
stirring rate =600 rpm; 1μL , 2μL , 4μL , 8μL and
16μL of 100mM H2O2 are injected at 100 seconds, 200
seconds, 300 seconds, 400 seconds and 500 seconds
respectively
Fig. 4 The TB graphs of screen printed planar
electrodes for detection of H2O2
(ruthenium
hexacyanoferrate(Ⅱ) : graphite carbon powders = 3 :
7) ; At 30 ℃ ; the operating potential = –0.2 V ; in 0.1
M KCl of 5 mL 0.05 M PBS buffer solution
( pH=7.4 ) ; stirring rate =600 rpm; 16μL of 100mM
H2O2 is injected per 100 seconds
7 cm
0.05 cm
0.5 cm
Preparation of the Screen Printed Planar Electrode :
The above mentioned mixture with the appropriate ratio (ruthenium hexacyanoferrate(Ⅱ) :
graphite carbon powders : carbon paste = 0.3 : 0.7 : 1) was evenly coated on the front side of screen
plate and then the PE paper was placed under the screen plate and the plastic plate was used to print
the mixture on the PE paper evenly. The electrode was dried in the oven and then we obtained the
screen printed planar hydrogen peroxide electrode. After the screen printed planar hydrogen peroxide
electrode was dried, the 2μL glucose oxidase solution( 3mg of glucose oxidase was dissolved in 500μL
PBS buffer solution ) was put onto the screen printed planar hydrogen peroxide electrode and the
electrode was dried at room temperature. Then 5μL of 1% Nafion solution(in 95% alcohol) was
dropped onto the electrode evenly and after the electrode was dried at room temperature, we obtained
the screen printed planar glucose electrode.
5μL of
2μL
1
glucose
oxidase
solution
was put
onto the
electrode
2
1%
Nafion
solution
was
dropped
onto the
electrode
evenly
Fig. 5 The TB graphs of screen printed planar
electrode for detection of glucose (ruthenium
hexacyanoferrate(Ⅱ) : graphite carbon powders = 3 :
7); At 30 ℃ ; the operating potential = –0.2 V ; in 0.1
M KCl of 5 mL 0.05 M PBS buffer solution ( pH=7.4 );
stirring rate =600 rpm; 1μL , 2μL , 4μL , 8μL and
16μL of 100mM glucose are injected at 100 seconds,
200 seconds, 300 seconds, 400 seconds ,and 500
seconds respectively
Fig. 6 The TB graphs of screen printed planar
electrode for detection of glucose (ruthenium
hexacyanoferrate(Ⅱ) : graphite carbon powders = 3 :
7) ; At 30 ℃; the operating potential = –0.2 V ; in 0.1
M KCl of 5 mL 0.05 M PBS buffer solution ( pH=7.4 );
stirring rate=600 rpm; 16μL of 100mM glucose is
injected per 100 seconds
CONCLUSIONS
The results showed that the responding current for the carbon paste electrode modified with the
ruthenium hexacyanoferrate(Ⅱ) was elevated significantly. The optimum weight ratio for
ruthenium hexacyanoferrate (Ⅱ) : graphite carbon powders was 3 : 7 . At 30℃ , -0.2V operating
potential, and in 0.05 M PBS buffer solution( pH = 7.4 ), when the screen printed planar electrode
was modified with the ruthenium hexacyanoferrate(Ⅱ) [ruthenium hexacyanoferrate(Ⅱ) : graphite
carbon powders = 3 : 7 ( weight ratio )] , the detection limit was 0.02 mM H2O2 , the linear range was
0.02～0.96 mM H2O2, R2=0.917, and the sensitivity was 28.77 μA/cm2ּmM H2O2 . For the glucose
screen printed planar sensor, the detection limit was 0.02 mM C6H12O6 ; the linear range was 0.02 ~
2.24 mM C6H12O6 ; R2 = 0.9983 and the sensitivity was 12.19 μA/cm2 mM C6H12O6 .
REFERENCES
1. S. J. Updike and G. P. Hicks, “The Enzyme Electrode,” Nature, 214, 986, (1967).
2. R. Garjonyte and A. Malinauskas, “Glucose Biosensor Based on Glucose Oxidase Immobilized in
Electropolymerized Polypyrrole and Poly(o-phenylenediamine) Films on a Prussian Blue-Modified
Electrode,” Sensors and Actuators B, 63, 122, (2000).