Abstract
Catalase (CAT) is a heme enzyme with a Fe(III/II) prosthetic group at its redox centre. CAT is present in almost all aerobic living organisms, where it catalyzes the disproportionation of H2O2 into oxygen and water without forming free radicals. In order to study this catalytic mechanism in detail, the direct electrochemistry of CAT has been investigated at various modified electrode surfaces with and without nanomaterials. The results show that CAT immobilized on nanomaterial modified electrodes shows excellent catalytic activity, high sensitivity and the lowest detection limit for H2O2 determination. In the presence of nanomaterials, the direct electron transfer between the heme group of the enzyme and the electrode surface improved significantly. Moreover, the immobilized CAT is highly biocompatible and remains extremely stable within the nanomaterial matrices. This review discusses about the versatile approaches carried out in CAT immobilization for direct electrochemistry and electrochemical sensor development aimed as efficient H2O2 determination. The benefits of immobilizing CAT in nanomaterial matrices have also been highlighted.
Highlights
The study of the direct electron transfer pathways of redox proteins or enzymes is very significant in understanding the redox proteins, as well as in development of enzyme biosensors, biofuel cells and biomedical devices [1]
In order to investigate this catalytic ability of CAT in detail, the direct electrochemistry of CAT at the transducer surface has to be examined, but earlier studies showed that immobilization of CAT directly on the bare electrode surface lead to poor electron transfer [12]
Zhou et al reported the direct electrochemistry of CAT on multiwalled carbon nanotubes (MWCNTs) and gold nanoparticles (GNPs) modified pyrolitic graphite electrode (PGE) [36]
Summary
The study of the direct electron transfer pathways of redox proteins or enzymes is very significant in understanding the redox proteins, as well as in development of enzyme biosensors, biofuel cells and biomedical devices [1]. The studies of redox proteins’ direct electrochemistry are important in understanding the mechanism of electron transfer between immobilized proteins and the electrodes. In order to investigate this catalytic ability of CAT in detail, the direct electrochemistry of CAT at the transducer surface has to be examined, but earlier studies showed that immobilization of CAT directly on the bare electrode surface lead to poor electron transfer [12]. This may be due to the fact that the Fe(III/II) group gets deeply buried inside the huge structure of CAT. This review mainly highlights the various electrode fabrication methods, their electrochemical characterizations, miscellaneous enzyme immobilization strategies used by researchers in the present and past decades, along with the benefits of using nanomaterials as enzyme immobilization matrices
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