A screen-printed amperometric sensor based on carbon ink bulk-modified with MnO2 decorated graphene oxide (MnO2/GO-SPE) nanocomposite was investigated for its ability to serve as a sensor towards nitrite. The composite was prepared by simple ultrasonication and reflux methodology and was characterized by FT-IR spectroscopy, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Atomic force microscopy and electrochemically using cyclic voltammetry, chronoamperometry and differential pulse voltammetry techniques. The MnO2/GO-SPE was found to exhibit an electro-catalytic activity for the electrochemical oxidation of nitrite in 0.1 M phosphate buffer solution (pH 7.4). The electrochemical oxidation of nitrite occurs at +0.55 V (Vs. Ag/AgCl) with a limit of detection (3σ) found to be 0.09 µM and with two linear ranges of 0.1 µM to 1 µM and 1 µM to 1000 µM with sensitivities of 1.25 µAµMˉˡcmˉ² and 0.005 µAµMˉˡcmˉ² respectively. Furthermore, the MnO2/GO-SPE showed an excellent anti-interference ability against a range of commonly encountered electroactive species and metal ions. Additionally, the fabricated MnO2/GO-SPE nitrite sensor presented excellent selectivity, reproducibility and stability. The present study widens the scope of applications of graphene-based nanocomposite materials for on-site monitoring of nitrite.

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The incorporation of carbon-based nanomaterials in screen-printed electrode sensors has overtaken traditional techniques in biological and environmental sample analysis where immediate on-site monitoring is required. Our review focuses on 1D and 2D biosensor materials.

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