A novel nitrite biosensor based on the direct electrochemistry of horseradish peroxidase immobilized on porous Co3O4 nanosheets and reduced graphene oxide composite modified electrode

Abstract

Porous Co3O4 hexagonal nanosheets (PCHNSs) with a well-defined morphology have been synthesized successfully via a hydrothermal process and followed by calcinations. Co3O4 nanosheets immobilizing horseradish peroxidase (HRP), together with reduced graphene oxide, have been used to modify glassy carbon electrode to fabricate a mediator-free biosensor. The morphology and structure of PCHNSs are studied by XRD, FESEM, and HRTEM techniques. Spectroscopic and electrochemical results reveal that Co3O4/rGO composite film is an excellent immobilization matrix with biocompatibility for enzymes, affording good enzymes' bioactivity and stability. Meanwhile, due to the unique structure of the modified electrode, the direct electron transfer of HRP is facilitated and the prepared nitrite biosensors display good performance---a wide linear range of 1 to 5400 μM, an extremely low limit of detection (LOD) as 0.21 μM and a limit of quantification as (LOQ) as 0.58 µM. This work suggests that Co3O4/rGO composite film is a potential matrix for enzymes' immobilization and biosensors' preparation.

Ion Selective Amperometric Biosensors for Environmental Analysis of Nitrate, Nitrite and Sulfate

“…The cathodic reduction of nitrite can be catalyzed by organic molecules as is the case for nitrate. Not only nitrite reductase (NiR) [31][32][33], but also cytochrome c-NiR [34,35], horseradish peroxidase [36], and hemoglobin [37] have been used to decrease the large overpotential for nitrite electroreduction. The electrooxidation of nitrite can be mediated by hemoglobin [38] and cytochrome c [39].…”

Graphene Oxide-Based Biosensors

“…Owing to the good biocompatibility and large surface area of Co 3 O 4 nanosheets (Figure 12), Co 3 O 4 nanosheets can be used to enhance the electric transfer between enzyme and electrode in a biosensor. Herein, Liu et al [21] firstly mixed Co 3 O 4 suspension with HRP, following with addition of rGO (Figure 13). Then the mixture was dropped cast onto the GCE to form the Co 3 O 4 -HRP/rGO/GCE electrode successfully.…”

An efficient LSPR method to quantitatively detect dimethoate: Development, characterization and evaluation

“…These limitations include complicated and time-consuming sample pre-treatment processes, but also involve expensive instruments only operated by trained personnel. Obviously, those expensive instruments cannot be effectively implemented to establish a quick determination method of analytes in the field [18,19].…”