Scanning Electrochemical Microscopy Imaging of DNA Arrays for High Throughput Analysis Applications - Applications of Electrochemistry and Nanotechnology in Biology and Medicine - page 125

i

1

ins
T

r

I L (2)

i 1 . 60185 § 2 . 37294 ·

T, f

0 . 40472 0 . 58819 exp

© ¹

L L

and for a conductive substrate:

i 0 . 76651 1 . 41332

§ · cond

T

r

I L 0 . 72627 0 . 26015 exp

© ¹

i L L

T, f

(3)
These limiting cases indicate that the mediator regeneration
either does not occur or proceeds at a diffusion-controlled rate.
However, in the actual course of the reaction, an electron-transfer
reaction occurs at a finite rate, to give a specific approach curve
that lies in between the insulating and the conductive cases. Figure
8 shows an example of an approach curve obtained for a
DNA-grafted, redox-polymer coated electrode (for the detailed
description, refer to section III.3). For a finite reaction that follows
primary kinetics, an analytical approximation, given by Eqs. (4)
and (5), is sometimes used for normalized distances 0.1 L
1.5. 30,34

§

ins
T

·

i I L

L ins

T

kin
S

¨
©

¸

I L I L I L 1

(4)

T

i

cond
T

I L T, f

¹

§ 1 . 0672 ·

0 . 68 0 . 3315 exp

© ¹

0 . 78377 L

kin
S

I L , k

(5)

eff

1 11

§ · § ·

L ¨

©

1 ¸

¹

¨
©

¸
¹

7 . 3

N L N L

1

110 40 L