Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5371423 | Biophysical Chemistry | 2010 | 7 Pages |
A large catalase (CAT) (Mr ~ 90 kDa), immobilized on multiwalled carbon nanotubes-Nafion® (MWCNT-NF) matrix and encapsulated with polyethylenimine (PEI) on glassy carbon electrode (GCE), showed a pair of nearly reversible cyclic voltammetric peaks for Fe(III)/Fe(II) couple with formal potential of about â0.45 V (vs. Ag/AgCl electrode at pH 7.5). PEI significantly reduced the charge transfer resistance and stabilized the bioelectrode through electrostatic interaction. The electron transfer rate constant and surface coverage of the immobilized CAT were 1.05 ± 0.2 sâ1 and 2.1 Ã 10â10 mol cmâ2, respectively. Studies on electrocatalytic activity and kinetics of GCE/MWCNT-NF/CAT/PEI for hydrogen peroxide (H2O2) showed the apparent Michaelis-Menten constant of 3 mM, linear response in the range of 10 μM to 5 mM, response time of ~ 2 s for steady state current, and detection limit of ~ 1 μM. A high operational and storage stability was also demonstrated for the bioelectrode. Hence, the direct electrochemistry of the large catalase and its potential biosensor application have been established through this investigation.
Graphical AbstractDownload full-size imageResearch Highlights⺠Direct electron tunneling between the large catalase and electrode is demonstrated. ⺠Polyethylenimine electrostatically stabilizes the catalase in the bioelectrode. ⺠The large catalase reduces overall charge transfer resistance of the bioelectrode.