Biology Reference
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voltammetric signal, EVLS E4 provides a higher and narrower
signal (confirmed by the theory in Ref. [5]).
(b) The electroactive species are adsorbed on the electrode surface
beforetheelectrontransferandEVLSE4givesthespecialsignal
which isimportant for the sensitiveODN detection.
11.2.2 EVLS of Adsorbed Species
As already mentioned above, the best EVLS E4 signal was observed
fortheelectroactiveparticle,whichispre-adsorbedontheelectrode
surface and undergoes an irreversible electron transfer. This
elimination signal corresponds to a well-developed and well-
readable peak-counterpeak. The theoretical curve (Fig. 11.1) has
been calculated according to the equations for the irreversible I - E
curve of totally adsorbed electroactive species [4]. The theoretical
form of the peak-counterpeak was experimentally verified by the
meansofhomo-ODN(adeninenonamer),whichisstronglyadsorbed
on a mercury electrode.
From the analytical point of view, two aspects are important
for an ODN transducer. First, the EVLS signal obtained for totally
Figure 11.1. (a) Theory: LSV and EVLS voltammograms. (b) Experiment:
LSV and EVLS voltammograms of homo-ODN (dA 9 )inacetatebuffer(pH
5.3). f ( I ): elimination function E4 for simultaneous elimination of kinetic
and charging currents, and conserving the diffusion current. I p and I p + I cp
are peak and peak-counterpeak heights, respectively. Scan rates for EVLS:
100, 200, 400 mV/s, reference scan 200 mV/s, time of accumulation 90 s,
and potential of accumulation
100 mV vs. Ag/AgCl/3M KCl.
 
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