Hybrid nanomaterial/catalase-modified electrode for hydrogen peroxide sensing

Abstract

Conjugation of biomolecules with hybrid nanomaterials offer opportunities in the assembly of (bio)sensors of improved electrochemical performance. This work reports on developing a novel catalase-functionalized hybrid nanomaterial for the detection of hydrogen peroxide (H 2 O 2 ). The rationally assembled (bio)sensor consists of iron nanoparticles coated with graphene's layers supported on multi-walled carbon nanotubes (Fe@G-MWCNTs), deposited at a screen-printed carbon electrode surface and functionalized with catalase. Transmission electron microscopy, X-ray diffraction-, X-ray photoelectron- and thermogravimetric-analysis were used to characterize the physicochemical properties of the hybrid nanomaterial and better understand its electrochemical behavior. The (bio)sensor response was linear from 0.1 to 7 mM, with a sensitivity of 0.059 μA/(μM.cm 2 ), a limit of detection of 28.2 μM, a Michaelis-Menten constant of 17.9 mM, and high reproducibility. The graphene flakes acted as a protective layer that prevented the loss of the Fe nanoparticles activity, thus improving the long-term stability of the (bio)sensor. • A hybrid nanomaterial (Fe@G-MWCNTs) of enhanced electro-analytical properties with respect to the individual components alone. • The hybrid as a suitable nanoenvironment for the catalase´s direct electrochemistry, maintaining its bioactivity and stability. • Cat/Fe@G-MWCNTs/SPCE biosensor with catalytic activity towards H 2 O 2 reduction, with high sensitivity and stability.