Inkjet-printed electrochemically reduced graphene oxide microelectrode as a platform for HT-2 mycotoxin immunoenzymatic biosensing

Jiri Kudr, Lei Zhao, Emily P. Nguyen, Henri Arola, Tarja K. Nevanen, Vojtech Adam, Ondrej Zitka, Arben Merkoçi. Biosensors and Bioelectronics, 2020

The design and application of an inkjet-printed electrochemically reduced graphene oxide microelectrode for HT-2 mycotoxin immunoenzymatic biosensing is reported. A water-based graphene oxide ink was first formulated and single-drop line working microelectrodes were inkjet-printed onto poly(ethylene 2,6-naphthalate) substrates, with dimensions of 78 μm in width and 30 nm in height after solvent evaporation. The printed graphene oxide microelectrodes were electrochemically reduced and characterized by Raman and X-ray photoelectron spectroscopy spectroscopies in addition to microscopies. Through optimization of the electrochemical reduction parameters, differential pulse voltammetry were performed to examine the sensing of 1-naphthol (1-N), where it was revealed that reduction times had significant effects on electrode performance. The developed microelectrodes were then used as an immunoenzymatic biosensor for the detection of HT-2 mycotoxin based on carbodiimide linking of the microelectrode surface and HT-2 toxin antigen binding fragment of antibody (anti-HT2 (10) Fab). The HT-2 toxin and anti-HT2 (10) Fab reaction was reported by anti-HT2 immune complex single-chain variable fragment of antibody fused with alkaline phosphatase (anti-IC-HT2 scFv-ALP) which is able to produce an electroactive reporter – 1-N. The biosensor showed detection limits of 1.6 ng ∙ mL−1 and a linear dynamic range of 6.3 – 100.0 ng ∙ mL−1 within a 5 min incubation with 1-naphthyl phosphate (1-NP) substrate.

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