Biomedical Engineering Reference
In-Depth Information
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FIGURE 13.4 Electropolymerization of 1,2-DAB on the top of Prussian blue-modifi ed electrode: 5 mM
DAB, 0.02 M phosphate pH 6.0 with 0.1 M KCl, 20 mV s 1 .
the electroactivity of the inorganic polycrystal, which is dependent on the presence of
counter-cations. As seen in Fig. 13.4, in the course of polymer growth, which is noticed
by the decrease of the current of monomer irreversible oxidation, the set of peaks pecu-
liar to Prussian blue redox activity is also changed: the peaks become wider and lower
indicating that a barrier to cations appears. Depending on the counter-cation, the perme-
ability of a non-conducting fi lm can thus be monitored during the deposition procedure.
Concerning analytical characteristics of the resulting Prussian blue (PB)-based
hydrogen peroxide transducer, the best performance characteristics were obtained for
PB electrodes covered with electropolymerized o -phenylenediamine. The reported
transducer remained at a 100% response state for more than 20 hours under continuous
fl ow of 0.1 mmol L 1 hydrogen peroxide (fl ow rate 1 ml min 1 ), which improves the
stability level among selective H 2 O 2 sensors by one order of magnitude. The selec-
tivity factor of the PB-poly (1,2-diaminobenzene)-based transducer relative to ascor-
bate is nominally 600. The PB-poly(1,2-diaminobenzene)-modifi ed electrode allows
the detection of hydrogen peroxide in fl ow-injection mode down to 10 7 mol L 1 with
a sensitivity of 0.3 A L mol 1 cm r2 , which is two times lower compared with the
uncoated Prussian Blue-based transducer [128].
Hence, non-conducting polymers deposited on the top surface of Prussian blue-
modifi ed electrodes only slightly decrease sensor response, but dramatically improve
both stability and selectivity of the transducer.
13.4.5 Nano-electrode arrays: towards the sensor with the
record analytical performances
Despite the possibility for detection of hydrogen peroxide down to 10 7 mol L 1
achieved, both clinical diagnostics and environmental control in certain cases require
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