Highly Sensitive Electrochemical Hydrogen Peroxide Sensor Based on Iron Oxide-Reduced Graphene Oxide-Chitosan Modified with DNA-Celestine Blue.

The present study describes a novel and very sensitive electrochemical assay for determination of hydrogen peroxide (H₂O₂) based on synergistic effects of reduced graphene oxide- magnetic iron oxide nanocomposite (rGO-Fe₃O₄) and celestine blue (CB) for electrochemical reduction of H₂O₂. rGO-Fe₃O₄ nanocomposite was synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy and cyclic voltammetry. Chitosan (Chit) was used for immobilization of amino-terminated single-stranded DNA (ss-DNA) molecules via a glutaraldehyde (GA) to the surface of rGO-Fe₃O₄. The MTT (3-(4,5-Di methyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide) results confirmed the biocompatibility of nanocomposite. Experimental parameters affecting the ss-DNA molecules immobilization were optimized. Finally, by accumulation of the CB on the surface of the rGO-Fe₃O₄-Chit/ssDNA, very sensitive amperometric H₂O₂ sensor was fabricated. The electrocatalytic activity of the rGO-Fe₃O₄-Chit/DNA-CB electrode toward H₂O₂ reduction was found to be very efficient, yielding very low detection limit (DL) of 42 nM and a sensitivity of 8.51 μA/μM. Result shows that complex matrices of the human serum samples did not interfere with the fabricated sensor. The developed sensor provided significant advantages in terms of low detection limit, high stability and good reproducibility for detection of H₂O₂ in comparison with recently reported electrochemical H₂O₂ sensors. [ABSTRACT FROM AUTHOR]