Scanning Electrochemical Microscopy Imaging of DNA Arrays for High Throughput Analysis Applications - Applications of Electrochemistry and Nanotechnology in Biology and Medicine - page 140

(a)
Figure 14. (a) Scheme of the enzyme-linked precipitation method to a sandwich
assay. A capture probe DNA (12-mer) formed spotted-type DNA microarray based
on the standard 5'-SH modification chemistry on evaporated gold films. The DNA
arrays were next treated with the target, 35-mer DNA in the presence of the bioti-
nylated signaling probe and subsequently reacted with streptavidin-alkaline phos-
phate. Precipitation of the insoluble reaction product deteriorates the conductivity
of the substrate. Simple negative feedback mode SECM report that to give surface
images. (b) SECM images of DNA spots. (A) Area scan of array of spots of 2.5u
2.0 mm, with the capture probes arrayed in spots in three rows at a distance of 1
mm, center to center. (B) A cross-section line scan reporting the current values vs.
relative horizontal distance of a part of the area described by the white line depicted
in (A). The concentration of target was 40 nM. Imaging measurements were carried
out using 2 mM ferrocenemonocarboxylic acid in 0.1 M phosphate buffer, pH 7.4,
0.1 M NaCl as mediator, E tip +0.6 V, E substrate -0.1 V (Ag/AgCl). The tip was a disk
Pt microelectrode with a diameter of 10 μm and scanned at a constant speed of 10
μm s -1 . Reprinted with permission from Ref. 51. Copyright (2007) American
Chemical Society.