Supporting Information
Cou
pling
I
nto the Base Pair Stack is Necessary for DNA
-
mediated
Electrochemistry
Alon
A. Gorod
etsky, Omar Green, Eylon
Yavi
n,
an
d Jac
queline K. Barton
*
Division
of Chemistry and Chemical Engi
neering
California Institute of Techn
ology,
Pasadena, California 91125
*to whom
corresponde
nce shoul
d be addr
essed
S
2
5
0
0
4
0
0
3
0
0
2
0
0
1
0
0
0
nm
5
0
0
4
0
0
3
0
0
2
0
0
1
0
0
0
n
m
1
.
5
1
.
0
0
.
5
0
.
0
-
0
.
5
-
1
.
0
-
1
.
5
nm
Figu
re
S
1
. AFM characterization
of DNA
-
modi
fied and
bare HOPG
.
Data were
collected
in
5 mM sodi
um
phos
pha
te
, 50
mM NaCl, pH
7.1
(tappi
ng
mode
). Typi
cal
AFM
image of A:
well matched
DNA on
HOPG, B: DNA featuring
an acetylene
-
TEMPO modi
fied uridine, and C: unm
odi
fied HOPG. Seque
nces for A are pyr
ene
-
(CH
2
)
3
CONH(CH
2
)
6
NHCO
-
5’
-
CTA CAG
TCG
T
-
3’ plus
well matched
com
plement and
for B are pyr
ene
-
(CH
2
)
3
CONH(CH
2
)
6
NHCO
-
5
’
-
CTACAG
TCG
T
-
3’ plus TEMPO
modi
fied com
plement.
S
3
1
0
2
0
3
0
4
0
5
0
6
0
7
0
8
0
9
0
0
.
3
6
0
.
3
7
0
.
3
8
0
.
3
9
0
.
4
0
0
.
4
1
0
.
4
2
0
.
4
3
0
.
4
4
Absorption (A.U.)
T
e
m
p
e
r
a
t
u
r
e
(
d
e
g
C
)
1
0
2
0
3
0
4
0
5
0
6
0
7
0
8
0
9
0
1
0
0
0
.
1
9
5
0
.
2
0
0
0
.
2
0
5
0
.
2
1
0
0
.
2
1
5
0
.
2
2
0
0
.
2
2
5
0
.
2
3
0
0
.
2
3
5
Absorption (A.U.)
T
e
m
p
e
r
a
t
u
r
e
(
d
e
g
C
)
Figu
re
S2
.
Melting
temperature determinations
of DNA modi
fied by
AQ through
an
acetylene linka
ge (top)
and unm
odi
fied DNA with the same seque
nce (bot
tom
). The
melting
temperature was determined through
appl
ication
of a sigm
oidal fit (red),
revealing
a melting poi
nt of 55
°C
for AQ modi
fied DNA, and 5
1
°C
for unm
odi
fied
DNA. Data were collected in 5 mM sodi
um
phos
pha
te
, 50
mM NaCl, pH
7.1
.
S
4
0
1
0
0
2
0
0
0
2
0
0
4
0
0
6
0
0
8
0
0
1
0
0
0
S
c
a
n
R
a
t
e
(
m
V
/
s
)
Current (nA)
Figu
re
S3
.
Scan rate depende
nce of DNA modi
fied by
AQ through
an
acetylene linka
ge.
Data were collected in
5 mM sodi
um
phos
pha
te
, 50 mM NaCl, pH
7.1
.
0
2
5
5
0
-
2
-
1
.
5
-
1
-
0
.
5
0
L
o
g
(
!
)
"
Epc
1
0
s
-
1
3
0
s
-
1
5
0
s
-
1
E
x
p
e
r
i
m
e
n
t
a
l
D
a
t
a
Figu
re
S4
.
Plot of peak splitting
Δ
E
pc
(
Δ
E
pc
= E
pc
-
E°) versus log (
ν
) (where
ν
= scan
rate) for DNA modified by AQ through
an acetylene linka
ge. Simulated curves
correspondi
ng
to k
s
values of 10 s
-
1
(blue), 30
s
-
1
(green) and
50 s
-
1
(red) are show
n for
com
parison.
1
1
Tende
r, L., Carter, M
.T., Murray, R.W.,
Anal. Chem.
,
1994
,
66
, 3173
-
3181