Figure 20 Influence of number of bilayers deposited on the amount of electroactive myoglobin in films constructed on rough PG with various polyanions. PSS and ds-CT DNA were adsorbed from 0.5M NaCl solutions

TCA, the FeIII reduction peak current increases and the FeII oxidation current decreases. This “catalytic” reduction peak current can be used to detect TCA. As TCA concentration increases, the reduction peak grows and the oxidation peak eventually disappears. This is because MbFeII is used up by the reducing TCA. Two MbFeIII molecules are generated for each TCA reduced. The electrochemical catalytic reduction of TCA with Mb is as follows:

(3)

Electrochemical reduction of myoglobin in DDAB films produces two strong reductant species. At pH 5.5, MbFeII is formed from MbFeIII at about −0.2 V, and MbFeI seems to be generated at about −1.1 V (Figure 22) [34, 35]. As described above, catalytic reduction of trichloroacetic acid occurs by reaction with MbFeII. CV of a Mb-DDAB electrode in buffer containing 30 mM trichloroethylene (TCE) (Figure 23) shows that the MbFeIII/MbFeII redox peaks