Amperometric detection of peroxides using peroxidase and porphyrin biomimetic modified electrodes

Biosensors designed with crosslinked redox hydrogel and horseradish peroxidase have been evaluated in aqueous and nonaqueous media. Electrodes made of a single layer of active material were prepared with Os(bYP)(2)ClPyCH2 NHPoly(allylamine) polymer, (PAA-Os), attached to the enzyme by PEG-400 bifunctional reagent with the Os sites acting as electron wires. The electrodes proved to be stable in the presence of organic solvent considering the time evolution of the redox charge and the catalytic current. However, a reasonable decrease in the enzyme response is apparent while increasing solvent content in solution for detection of hydrogen and lauroyl peroxide. As an alternative biomimetic strategy, electrodes were modified with consecutive layers of PAA-Os and electropolymerized Fe-protoporphyrin IX. The electrochemical detection of peroxides was also possible with this system, proving that the poly[Fe-protoporphyrin IX]/Osmium complex system can mimic the peroxidase activity towards hydrogen and organic peroxides. The replacement of Fe-protoporphyrin by Ni-protoporphyrin IX and PAA-Os by PAA in different experiments demonstrates that the mechanism for peroxide reduction involves both Os and Fe-protoporphyrin IX sites. The enzymatic electrodes were applied to benzoyl peroxide quantitation in a pharmaceutical product. The method validation demonstrates that a simple and rapid FIA detection can be applied.