A Study of the Screen Printed Planar Electrode Modified with Ruthenium
Hexacyanoferrate and Its Application to Glucose Biosensor
Kuo-Hsiang Liao(廖國翔), Ting-Li Lin(林庭立), Hau Lin(林浩)
Department of Chemical and Materials Engineering, Southern Taiwan University
*E-mail: hauc@mail.stut.edu.tw
Abstract
Diabetes is one of the top ten causes of death for the
people in Taiwan. Therefore, developing a glucose
biosensor which can detect glucose rapidly and
conveniently is an important research subject.
Nowadays, sometimes the preservatives are used in the
food industry for the purpose of food preservation.
Therefore, a hydrogen peroxide sensor also becomes an
important research subject. 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
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.
Keywords: Ruthenium Hexacyanoferrate, Carbon Paste
Electrode, Screen Printed Planar Electrode, Biosensor
1
Introduction
In recent years, diabetes is one of the ten main causes of
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
death for the people in Taiwan. At present, there is no
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
must be performed by the medical examiners in the
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
peroxide. The electrode releases the electrons at the
( weight ratio )] , the detection limit was 0.02 mM H2O2 ,
the linear range was 0.02～0.96 mM H2O2, R2=0.917,
is converted to the oxidizing state. The responding current
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
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. The glucose and oxygen can be catalyzed
by the glucose oxidase and the glucose is oxidized to
gluconic acid and the oxygen is reduced to hydrogen
reductive potential and converts the mediator to the
reductive state. Then the mediator at the reductive state
releases the electrons to reduce the hydrogen peroxide to
water and consequently the mediator at the reductive state
for detecting the hydrogen peroxide is used to measure the
amount of hydrogen peroxide and consequently determine
2.3 Preparation of the carbon paste electrode
the concentration of the glucose. Therefore, the detecting
Take one section of 7 cm electric wire with 0.05 cm inside
technique for the hydrogen peroxide is an important
diameter. After depriving the coating 0.5 cm length from
research subject. Because ruthenium hexacyanoferrate(Ⅱ)
both ends, the nake-ended wire was washed, dried and
possesses
catalytic
ready for use. Then the ruthenium hexacyanoferrate(Ⅱ)
characteristic, it can be used to elevate the responding
powders, graphite carbon powders and carbon paste were
current for detection of reduction of hydrogen peroxide. A
mixed
study
ruthenium
hexacyanoferrate(Ⅱ) : graphite carbon powders : carbon
hexacyanoferrate(Ⅱ) to modify the carbon paste electrode
paste = 0.3 : 0.7 : 1). After the mixing was complete, the
and screen printed planar electrode which were used as the
mixture was evenly coated on the nake-ended electric wire
working electrodes to detect the responding current of
and dried in the oven and then we obtained the carbon
reduction of hydrogen peroxide in the phosphate buffer
paste electrode.
the
was
excellent
conducted
conductivity
to
use
and
the
with
the
appropriate
ratio(ruthenium
solution(PBS) and then the concentration of hydrogen
peroxide could be obtained from the responding current
and consequently, the concentration of the glucose could be
2.4 Preparation of the screen printed planar electrode
determined. The carbon paste electrode was used to
The above mentioned mixture with the appropriate ratio
determine the optimum operating potential and weight ratio
(ruthenium
in this research. After the optimum operating conditions
powders : carbon paste = 0.3 : 0.7 : 1) was evenly coated on
were determined, the screen printed planar electrode was
the front side of screen plate and then the PE paper was
used to determine the sensitivities of detection the
placed under the screen plate and the plastic plate was used
hydrogen peroxide and glucose.
to print the mixture on the PE paper evenly. The electrode
hexacyanoferrate(Ⅱ)
:
graphite
carbon
was dried in the oven and then we obtained the screen
2
Experimental
printed planar hydrogen peroxide electrode. After the
2.1 Chemicals and reagents
screen printed planar hydrogen peroxide electrode was
Ruthenium （ Ⅲ ） Chloride Hydrate(RuCl3); Potassium
dried, the 2μL glucose oxidase solution( 3mg of glucose
Hexacyanoferrate(II)(K4[Fe(CN)6] ． 3H2O) ; Hydrogen
oxidase was dissolved in 500μL PBS buffer solution ) was
Peroxide (H2O2); Glucose Oxidase(EC 1.1.3.4, Type X-S:
put onto the screen printed planar hydrogen peroxide
from Aspergillus Niger, 245900 units/g); Graphite Carbon
electrode and the electrode was dried at room temperature.
Powder; Carbon Paste; Cyclohexanone(C6H10O); Nafion;
Then 5μL of 1% Nafion solution(in 95% alcohol) was
Potassium Dihydrogenphosphate (KH2PO4); Potassium
dropped onto the electrode evenly and after the electrode
Chloride (KCl); D(+)-Glucose Monohydrate(C6H12O6).
was dried at room temperature, we obtained the screen
printed planar glucose electrode.
2.2 Equipment
Electrochemical Analyzer (CHI 614A, CH Instruments, Inc)
2.5 Amperometric measurement for the carbon paste
was used to measure the activity of electrode by Cyclic
electrode and the screen printed planar electrode
Voltammetry ( CV ) and Time Base ( TB ) mode ; pH
The Carbon Paste Electrode and the Screen Printed Planar
meter (Metrohm 731); Constant Temperature Thermal Bath
Electrode were used as the working electrodes, the Coiled
(Wisdom BC-2DT 10L); Oven (DENG YNG) ; Electric
Platinum Wire was used as the counter electrode and the
Stirrer(Fargo); Carbon Paste Electrode and Screen Printed
Ag / AgCl was used as the reference electrode. The three
Planar Electrode were used as the working electrodes,
electrode system was placed in the 0.05 MPBS buffer
Coiled Platinum Wire was used as the counter electrode
solution. The electrochemical analyzer was used to plot the
and Ag / AgCl was used as the reference electrode.
CV diagrams and to detect the responding current of
hydrogen peroxide for the Time Base ( TB ) mode.
3
Results and Discussion
electrodes for detection limit and linear range of
3.1 Determination of the Operating Potential by CV
Diagram
The CV diagrams were plotted for the carbon paste
electrode
modified
with
the
ruthenium
hexacyanoferrate(Ⅱ) (ruthenium hexacyanoferrate(Ⅱ) :
graphite carbon powders : carbon paste = 0.3 : 0.7 : 1) and
the unmodified carbon paste electrode. The above
glucose
Figure 5 shows the TB graphs of screen printed planar
electrodes for detection of the detection limit of glucose.
Figure 6 shows the TB graphs of screen printed planar
electrodes for detection of the linear range of glucose. The
results showed that 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 12.19μA/cm2 mM
C6H12O6 .
mentioned two electrodes were placed in 0.1 M KCl of 5
mL 0.05 M PBS buffer solution (pH =7.4) and after
4
deoxygenating by purging nitrogen gas, the system was
scanned with 50 mV/s scanning rate. Figure 1 shows the
CV graphs of (A) carbon paste electrode modified with
ruthenium hexacyanoferrate(Ⅱ) and (B) the unmodified
carbon paste electrode. In order to reduce the interference
of oxygen and avoid the inteferring substances ( Ascorbic
acid, Uric acid, and Acetaminophen etc.) in human body,
the operating potential at –0.2 V was chosen in this
research.
3.2
Determination
of
the
ratio
of
ruthenium
hexacyanoferrate(Ⅱ) to graphite carbon powders by
TB graphs
The TB graphs for the carbon paste electrodes with
different ratios of ruthenium hexacyanoferrate(Ⅱ)
to
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 .
graphite carbon powders are shown in Figure 2 . Figure 2
shows
that
when
the
ratio
of
ruthenium
hexacyanoferrate(Ⅱ) to graphite carbon powders is 3:7,
the responding current is the highest. Therefore the weight
ratio of ruthenium hexacyanoferrate(Ⅱ) : graphite carbon
powders = 3 : 7 will be used to make the working electrode
in this study.
3.3 The study of the TB graphs of screen printed planar
electrodes for detection limit and linear range of
hydrogen peroxide
Figure 3 shows the TB graphs of screen printed planar
electrodes for detection of the detection limit of H2O2.
Figure 4 shows the TB graphs of screen printed planar
electrodes for detection of the linear range of H2O2 . The
results showed that 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 .
Figure 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:
3.4 The study of the TB graphs of screen printed planar
-0.6～+0.6 V).
Figure 2: TB graphs of the carbon paste electrodes for
different ratios of ruthenium hexacyanoferrate(Ⅱ) to
Figure 4: The TB graphs of screen printed planar
graphite
carbon
hexacyanoferrate(Ⅱ)
(ruthenium
powders;
the
ruthenium
to graphite carbon powders are
electrodes for detection of the linear range of H2O2
hexacyanoferrate(Ⅱ)
:
graphite
carbon
powders = 3 : 7) .
〔(A) 0:10(unmodified carbon paste electrode) (B) 1:9
(C) 2:8 (D) 3:7 (E) 4:6 (F) 5:5〕.
Figure 3: The TB graphs of
screen printed planar
electrodes for detection of the detection limit of H2O2
(ruthenium hexacyanoferrate(Ⅱ): graphite carbon powders
= 3 : 7).
Figure 5: The TB graphs of screen printed planar
electrode for detection of the detection limit of glucose
(ruthenium hexacyanoferrate(Ⅱ)
powders = 3 : 7).
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electrode for detection of the linear range of glucose
(ruthenium hexacyanoferrate(Ⅱ) : graphite carbon
powders = 3 : 7).
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