TELKOM
NIKA Indonesia
n
Journal of
Electrical En
gineering
Vol. 12, No. 10, Octobe
r 20
14, pp. 7191
~ 719
5
DOI: 10.115
9
1
/telkomni
ka.
v
12i8.551
7
7191
Re
cei
v
ed
De
cem
ber 2
8
, 2013; Re
vi
sed
Jul
y
3, 2014;
Acce
pted Jul
y
28, 201
4
The interaction of Aliza
r
in Red with Try
p
tophan by
Voltammetry
Yu Zhuan-Ni
1,2
, Wang Qiang
2
1
Colle
ge of Ch
emistr
y
a
nd C
h
emical E
ngi
ne
erin
g, Ocean U
n
iversit
y
of Ch
i
na,
Qingda
o, 266
109, PR Ch
in
a
2
Colle
ge of ch
e
m
istr
y
an
d ph
a
rmaceutic
al sci
ence, Qing
da
o Agricult
ure Un
i
v
ersit
y
,
Qingd
ao, 26
61
00, PR Chi
n
a
Correspo
n
d
i
n
g
author, e-ma
i
l
: tsingtao-
w
q
@16
3
.com
A
b
st
r
a
ct
T
he inter
a
ctio
n of Ali
z
a
r
in
Red (AR) w
i
t
h
T
r
yptoph
an
(T
rp) w
a
s investigate
d
by fi
rst order
deriv
ative
lin
e
a
r sw
eep
volt
ammetry. In
pH5.2
Na
Ac-
H
Ac b
u
ffer s
o
luti
on, AR
h
ad
a w
e
ll-
defi
n
e
d
volta
m
metric r
eductiv
e
p
eak
at -0.3
92V(vs
.
SCE).Afte
r T
r
p a
dditi
on, th
e
pe
ak curr
ent
of AR
decre
as
e
d
app
arently w
i
t
h
no ch
an
ge o
f
the
peak p
o
tentia
l an
d no
app
eara
n
ce
of
new
peaks. T
he study a
b
o
u
t th
e
effect of scan r
a
te on
pe
ak cu
rrent show
ed t
hat a n
e
w
elec
tro-inactiv
e
co
mp
lex w
a
s for
m
e
d
as
a res
u
l
t
of
interacti
on of A
R
w
i
th T
r
p, w
h
ich decr
ease
d
t
he p
eak
curr
en
t. Based on t
h
e formatio
n
of
AR-T
rp co
mpl
e
x,
the con
d
iti
ons
of interacti
on
a
nd t
he
el
ectroc
he
mic
a
l d
e
tecti
on w
e
re car
e
fu
lly inv
e
stig
ated
and th
e bi
nd
in
g
ratio w
a
s obt
ai
ned
by
mol
e
ra
tio metho
d
. F
i
n
a
lly th
e ch
arac
ter of the e
l
ect
r
ode
process
w
a
s discusse
d
by
the effect of sc
an rates on
A
R
-Trp interaction system
.
Ke
y
w
ords
:
Ali
z
a
r
in R
ed, T
r
yptoph
an, li
near
sw
eep volta
m
metry, inter
a
cti
o
n
Copy
right
©
2014 In
stitu
t
e o
f
Ad
van
ced
En
g
i
n
eerin
g and
Scien
ce. All
rig
h
t
s reser
ve
d
.
1. Introduc
tion
Tryptoph
an, whi
c
h is al
so
calle
d amino
indole p
r
opio
n
ic a
c
id, is a kind of natu
r
al amino
ac
id and one of the human ess
ential amino
ac
ids
.It is
the
prec
ursor
of the
k
e
y human
neurotra
nsmit
t
er 5
-
hydroxytry
ptophane
and ha
s
a
ce
rtain se
d
a
tive
effect su
ch as sle
e
p
inhibition, te
mperature
re
gulation, pain
sen
s
itiv
ity and aggressive
behavio
r [1, 2], etc. Up to now,
the stu
d
y on
t
he inte
ra
ction
of tryptop
h
a
n
an
d ot
h
e
r substa
nces ha
s b
een
p
r
o
c
e
eding
mo
stly
by
ultraviolet sp
ectro
s
copy or fluoresce
nce
spect
r
o
s
cop
y
[3-5], which
is seldom p
r
oce
edin
g
by the
electrochemi
c
al metho
d
. And elect
r
o
c
hemically
act
i
ve dyes are
used a
s
probe
s not onl
y to
investigate
th
e interactio
n
mech
ani
sm
b
e
twee
n el
ectro-a
c
tive sub
s
tance
s
and
a
m
ino a
c
id
s
by
the ele
c
tro
c
h
e
mical
meth
o
d
but
also to
potentially
d
e
velop
a n
e
w ele
c
troa
nalytical m
e
thod
f
o
r
amino
acid
d
e
tection [6,
7]. In this pa
pe
r, an el
ect
r
o-active dye Ali
z
ari
n
Red
(A
R)
wa
s
sele
ct
ed
as a p
r
ob
e to investigate
its intera
ction
with
Trp by l
i
near
sweep
voltammetry. In the sele
cted
pH5.2
NaA
c
-HAc
buffer
solution, the
AR mole
cul
e
s a
r
e n
egati
v
ely cha
r
ged
, while the
Trp
molecule
s (isoele
c
tric p
o
in
t, pI=5.89) are mainly
posi
t
ively charge
d, so they ca
n bind togeth
e
r
by their ele
c
trostatic attra
c
t
i
on. Th
e
stud
y about
the
effect of
scan
rate on
pe
ak
current in
dicated
that the inte
raction
of AR
with T
r
p
co
ul
d form
an
ele
c
tro
-
ina
c
tive
compl
e
x, whi
c
h
de
cre
a
sed
the
redu
ctive pe
ak current.Base
d
on the
formation
o
f
the AR-Trp
complex, the con
d
itions of
intera
ction
an
d the
ele
c
tro
c
hemi
c
al
d
e
tection
were
carefully i
n
vestigated a
n
d
the bi
ndin
g
ra
tio
wa
s obtaine
d
by mole ratio method. In addition,
the characte
r of the electro
d
e
pro
c
e
ss
was
discu
s
sed.
2. Materials
and Method
s
2.1. Reage
n
ts
Tryptoph
an (Trp, che
m
b
a
se
)sto
ck sta
ndard solutio
n
(0.2
04m
g/ml) wa
s
p
r
e
pare
d
by
dissolving
0.
0408
g T
r
p i
n
200
ml
water. The
sol
u
tio
n
was dilute
d to
co
nveni
ent con
c
ent
ration
with wate
r properly in the
experim
ent. Alizari
n
Red
(AR, Sinopha
rm Chemi
c
al
Rea
gent Co.,Ltd)
stock stand
ard
sol
u
tion (0.
3605m
g/ml) wa
s
p
r
ep
are
d
by dissolving
0.0721
g AR
in 200
ml water.
0.2
mol/l HAc-NaA
c
b
u
ffer
solutio
n
wa
s
use
d
to re
gul
ate pH valu
e
of the intera
ct
ion medi
um. All
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 12, No. 10, Octobe
r 2014: 719
1
– 7195
7192
the ch
emi
c
al
s u
s
ed
were
of analytical
rea
gent
g
r
a
de with
out fu
rther pu
rificat
i
on an
d d
o
u
b
ly
dis
t
illed
water was
us
ed for mak
i
ng
s
o
lutions
[8].
2.2. Appar
a
tus
A model JP
-3
03 pola
r
og
ra
phic a
nalyzer (Ch
eng
du Apparatus F
a
ctory, China
)
wa
s used
in this wo
rk.
Voltammetri
c
curve
s
were
record
ed in
a three
-
ele
c
trode ele
c
tro
c
hemical cell
at
different tem
peratu
r
e. A drop
ping me
rcu
r
y el
ect
r
o
de (DME
) a
s
wo
rki
ng el
ectro
de, a SCE
referen
c
e el
e
c
trod
e an
d a
platinum
-wi
r
e
auxiliary el
e
c
trode
we
re u
s
ed. All the values
of pH
we
re
measured wit
h
a pHS-25 a
c
idity meter (Shangh
ai Lei
ci Instrument
Facto
r
y, Chin
a)
2.3. Procedu
r
e
4.0ml of 0.2
m
ol/l pH5.2
HAc-NaAc b
u
ffe
r sol
u
tion
, 1ml of 0.3605mg/ml A
R
and
an
approp
riate a
m
ount of
sta
ndard T
r
p
so
lution were
p
l
ace
d
in
a d
r
y 10ml
colo
ri
metric tube i
n
seq
uen
ce.Th
e
mixture
s
were
diluted to
scale
wi
th
water an
d sh
ook
well, th
e
n
the first o
r
der
derivative
lin
ear swee
p voltammetric
pea
k curre
n
ts(
) were recorded in t
he following
con
d
ition
s
: p
o
tential sca
n
rate,900
mv/s; potentia
l
range, -0.2~-0.7V(vs.SCE
)
.A blank
solu
tio
n
without T
r
p
were me
asured in th
e
sa
me c
onditio
n
s
a
nd its re
d
u
ctive pe
ak
curre
n
t(
0
) wa
s
obtaine
d,and
then the difference of pea
k curre
n
t(
0
)wa
s
cal
c
ulate
d
.
3. Results a
nd Discu
ssi
ons
3.1. Electroc
h
emical Beh
a
v
i
ors of AR in the Abse
nce and Pre
sence o
f
Trp
At the optimized
experi
m
ental condi
tions, t
he first ord
e
r d
e
rivative linear swe
ep
voltammogra
m
s of AR in the ab
sen
c
e
(
curve 1) a
nd p
r
esen
ce
(curv
e
2)of Trp
we
re re
co
rde
d
a
n
d
sho
w
n in Fig
u
re 1. After Trp wa
s ad
ded
, the r
eductiv
e
pea
k cu
rre
nt of
AR decreased app
are
n
tly
with no chan
ge of the red
u
ctive
pea
k p
o
tential and n
o
appe
ara
n
ce
of new pea
ks in the sel
e
cted
potential
ran
ge. As fo
r t
he rea
s
on, t
here
maybe
two p
o
ssibl
e
differe
nt o
p
inion
s
: (1)
The
decrea
s
e of
diffusion
coef
ficient after the additio
n
o
f
Trp; (2) Th
e formation o
f
electro
-
ina
c
t
i
ve
compl
e
x an
d
no
cha
nge
s of diffusio
n
coeffici
ent. T
hen the
diffu
sion
co
efficie
n
ts of A
R
in
the
absen
ce an
d
pre
s
en
ce
of Trp
were co
mpared.Fr
om
Figure 4, it coul
d be
see
n
that no ma
tter
w
h
e
t
he
r
T
r
p w
a
s
pr
es
e
n
t
o
r
no
t,
increased linearly
with
v
1/2
incre
a
sin
g
at hi
gh
er
scan
rate
s.
The equ
ation
s
we
re a
s
follows:
=12
528
v
1/2_
3953.0(n=6,R
2
=
0
.9
99
5
)
an
d
=118
39
v
1/2_
3623.8(n=6,R
2
=0.99
97)
1) pH5.2HA
c
-NaAc
＋
0.0
3
6
05mg/ml AR,
2) 1
＋
0.00
204
mg/ml Trp
Figure 1. First Order
De
rivative Linear S
w
ee
p
Voltam
mograms of
AR-T
rp Intera
ction System
Acco
rdi
ng to
the gene
ral
prin
cipal of
electr
ochemi
c
al rea
c
tion,the slo
pe ite
m
of the
linear eq
uatio
n of
~
v
1/2
con
t
ains th
e diff
usio
n
coeffici
ent facto
r
, an
d the
si
ze of
the sl
ope i
s
0.
2
0
.
4
0.
6
2
1
0.
5
μ
A
-
E
/V
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
The interactio
n of Alizarin
Red
with Tryptopha
n by V
o
ltam
m
e
try (Yu Zhuan
-Ni
)
7193
related
to the
diffusio
n
co
efficient in
th
e case of
oth
e
r exp
e
rim
e
n
t
al co
ndition
s un
cha
nge
d [
9
-
11]. By comp
aring th
e slo
pes
of the lin
ear e
quatio
n in the ab
sen
c
e and p
r
e
s
en
ce of Trp, so
it
coul
d b
e
fou
nd that th
e
diffusion
coe
fficient was
essentially th
e same. A
c
cording
to t
he
statement
of
Kelly [12], it
might
be
th
at AR
i
n
tera
cting
with
Trp form
ed
a
compl
e
x of l
a
rge
molecula
r we
ight, whi
c
h
couldn't
be
re
duced o
n
the
Hg
ele
c
trod
e su
rfa
c
e, an
d the e
quilib
rium
con
c
e
n
tration
of free AR i
n
solutio
n
de
creased,so
the
pea
k current
decrea
s
e
d
ob
viously with t
h
e
pea
k potenti
a
l unch
ang
e
d
. In addition, the fact
tha
t
the difference of pea
k current decre
a
s
ed
linearly with
t
he
in
crea
se o
f
Trp co
ncent
ration also
ex
plaine
d p
r
etty well
that the
formed
AR-Trp
compl
e
x wa
s electro-i
n
a
c
tive.
3.2. Optimization of Inter
action
Condi
tions
3.2.1. Effec
t
s
of Buffer
s a
nd pH
In orde
r to investigate the
effect of vari
ous b
u
ffers o
n
the intera
ction between
AR and
Trp.B-R, Tri
s
-HCl, bo
rax,
NH
3
-N
H
4
Cl, HA
c-NaA
c
were te
sted
respe
c
tively, and th
e
re
sults
indicated that
in HAc-NaA
c
buffer th
e
pea
k shap
e wa
s go
od an
d the value
of
wa
s the
maximum. Th
e experi
m
ent
s indi
cate
d th
at the buffer
pH h
ad g
r
eat
influen
ce o
n
the de
cre
a
se
of
pea
k cu
rrent. As sh
own in Figu
re 2, the maximum
appe
are
d
at
pH 5.2,so p
H
5.2
wa
s
sele
cted
a
s
t
he o
p
timal p
H
. In a
dditio
n
, with th
e i
n
crea
se
of p
H
valu
e, the
re
du
ctive p
eak
potential
shif
ted ne
gativel
y, which in
di
cated
t
hat t
he hyd
r
og
en
ion
s
were i
n
volved in
the
electrode
re
a
c
tion. Th
e op
timal volume
of HAc-Na
Ac buffer at p
H
5.2 wa
s e
s
ti
mated an
d 4.
0ml
of buffer wa
s
use
d
in the following
experi
m
ents.
Figure 2. Dep
ende
nces o
n
the De
cre
a
se
of
Peak Cu
rrent Against p
H
(0.03
605
m
g
/ml
AR
＋
0.002
04
mg/ml Trp
)
3.2.2. Effec
t
of AR Con
c
e
n
tra
t
ion
The effect of AR con
c
ent
ration was
studied
with 0.
0020
4mg/ml Trp, and it could be
found th
at th
e con
c
entration of A
R
at
0.036
05mg/
ml gave th
e
maximum
. Wh
en A
R
con
c
e
n
tration
wa
s m
o
re th
an 0.0
360
5m
g/ml, the
began to
de
cre
a
se.So
0.036
05mg/ml
of
AR wa
s re
co
mmend
ed in
sub
s
e
que
nt studies.
3.2.3. Stability
The expe
rim
ents sho
w
ed
that
reached
the maximum immediatel
y after mixture at
room tem
perature a
nd re
mained
stabl
e for at le
a
s
t one hou
r. T
he influen
ce
of temperatu
r
e on
the system was al
so estim
a
ted
at 10°C,
room tempe
r
ature an
d 35°
C, sep
a
rately
and no obvio
us
differen
c
e
wa
s fou
nd. Diffe
rent a
ddin
g
o
r
de
rs
of AR,T
rp a
nd
HAc-NaAc buffe
r
were te
sted
a
nd
the results
sh
owe
d
that the best additio
n
s
equ
en
ce was HA
c-NaA
c
buffer, AR and Trp.
3.3. The Bin
d
ing Ratio o
f
AR and Tr
p
By keepin
g
t
he Trp con
c
entration
of
1.0×1
0
-4
mol/l con
s
tant a
n
d
ch
angi
ng t
he AR
con
c
e
n
tration
[13], the rel
a
tionship b
e
twee
n
and
AR con
c
entration was
ob
tained a
n
d
3.
5
4
.
0
4.
5
5
.
0
5.
5
6
.
0
0
100
200
300
400
500
600
△
I
Р
’
(nA
)
pH
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ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 12, No. 10, Octobe
r 2014: 719
1
– 7195
7194
sho
w
n
in Fi
gure
3. In
the figu
re,ab
and
b
c
se
gments inte
rse
c
ted i
n
th
e b
point,
whose
corre
s
p
ondin
g
ho
rizontal
coo
r
din
a
te v
a
lue
wa
s
used to
cal
c
ul
a
t
e the bi
ndin
g
ratio,
and
the
bindin
g
ratio
of AR and Trp wa
s 2:3.
Figure 3. Rel
a
tionship bet
wee
n
AR and
Trp
3.4. Effec
t
of Scan Ra
tes
on the Electr
ode Proce
s
s
The sca
n
rat
e
s h
ad imp
o
rtant effect on
the elect
r
od
e pro
c
e
s
s.Th
e relatio
n
ship
betwee
n
v
1/2
and
of AR in the abse
n
ce (cu
r
ve1
)
and presen
ce
(cu
r
ve2) of T
r
p we
re sho
w
n in Figure 4.
It could be
seen that no
matter wh
eth
e
r Trp wa
s
p
r
esent or n
o
t, the relation
ship between
and
v
1/2
devia
ted from a straight line and
curved u
p
wa
rd at lowe
r scan rate
s,whi
c
h indicate
d that
the elect
r
od
e
pro
c
e
ss
wa
s mainly
con
t
rolled
by ad
sorption;an
d
whe
n
the scan rate
s
were
highe
r,
wa
s in linear relati
on with
v
1/2
, whi
c
h showe
d
that the el
ectrod
e proce
ss
wa
s mainly
driven by diffusio
n
[14].
1) pH5.2HA
c
-NaAc
＋
0.0
3
6
05mg/ml AR,
2) 1
＋
0.00
204
mg/ml Trp
Figure 4. Dep
ende
nces of
on Potential Scan Rates
The effect o
f
scan rates on the pea
k potent
ial o
f
A
R
-Trp int
e
ra
ct
ion sy
st
em wa
s
investigate
d
. As mentio
ne
d above, the
redu
ctive p
e
a
k
pote
n
tial be
fore an
d after the additio
n
of
Trp
wa
s the
same i
n
e
a
ch
of the
sel
e
cte
d
sca
n
rate.
Whe
n
the
scan
rate
s
we
re
lower, th
e
pe
ak
potential ba
si
cally had
no
cha
nge
s, which
wa
s
in
good a
g
reem
ent with the
cha
r
a
c
ter
of the
reversibl
e
re
action; an
d when the
scan
rates
we
re h
i
gher, the
red
u
ctive pea
k p
o
tential shifte
d
negatively fro
m
-0.3
80 to
-0.392V
(vs.S
C
E)
with th
e i
n
crea
se
of scan rate in
the
scan
rate
ra
nge
of 0.4~0.9V/s, which in
dica
ted that t
he electro
de p
r
o
c
e
ss
wa
s irreve
rsibl
e
.
24
68
1
0
1
2
1
4
1
6
50
0
10
00
15
00
20
00
25
00
c
a
b
△
I
Р
’(
nA
)
C
AR
S
(1
0
-5
mo
l
/
L
)
0.
3
0
.
4
0
.
5
0
.
6
0.
7
0
.
8
0.
9
1
.
0
0
20
00
40
00
60
00
80
00
10
00
0
12
00
0
2
1
I
p
’
(nA
)
v
1/
2
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
The interactio
n of Alizarin
Red
with Tryptopha
n by V
o
ltam
m
e
try (Yu Zhuan
-Ni
)
7195
4. Conclusio
n
The inve
stiga
t
ion on the in
teractio
n of AR with T
r
p
was d
e
scri
bed
by voltammetry. Due
to
the
alm
o
st unchan
ged di
ffusion co
efficient
after
Trp
addition, th
e
bindin
g
of p
o
s
itively ch
arg
e
d
Trp
with
neg
atively cha
r
g
ed A
R
resulted in
the
formation
of a
new ele
c
tro
-
i
nactive
co
mp
lex,
whi
c
h d
e
crea
sed th
e re
du
ctive peak
cu
rrent. Based
o
n
the form
atio
n of the AR-T
rp compl
e
x, the
con
d
ition
s
of
intera
ction a
n
d
the ele
c
tro
c
hemi
c
al det
ection we
re carefully
inve
stigated
an
d
the
bindin
g
ratio
wa
s obtain
e
d
by mole ratio
method.
Fin
a
lly, the character
of the electro
de p
r
o
c
ess
wa
s discu
s
se
d by the effect of scan
r
a
t
e
s on A
R
-Tr
p
int
e
ra
ct
ion sy
st
em.
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