Graphene oxide-gold nanozyme for highly sensitive electrochemical detection of hydrogen peroxide

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>We fabricated a nafion/graphene oxide-gold nanoparticle (GO-AuNP) hybrid modified indium tin oxide (ITO) electrode and proposed an electrochemical method to detect hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>) using 3,3,5,5,-tetramethylbenzidine (TMB) as a redox mediator. The GO-AuNP hybrids were employed as nanozymes, which function as peroxidase mimics and show highly effective catalytic activity. Based on the high catalytic activity, enzyme mimics were entrapped on the ITO electrode to construct an electrochemical H<SUB>2</SUB>O<SUB>2</SUB> sensor by coating nafion polymer. During the catalytic reaction, the peroxidase substrate TMB was oxidized to form the TMB oxidation product, which not only produces a blue color detected by absorbance change, but also generates an electrochemical current. As a result, both spectrophotometric and electrochemical methods were used to determine H<SUB>2</SUB>O<SUB>2</SUB> concentration. The spectrophotometric detection displayed a linearity for H<SUB>2</SUB>O<SUB>2</SUB> concentration from 10 μM to 5 mM (r<SUP>2</SUP> = 0.989), with an estimated detection limit of 2 μM. In the electrochemical detection, the TMB peak current had a good linear relationship with H<SUB>2</SUB>O<SUB>2</SUB> concentration from 10 nM to 10 mM, with an estimated detection limit of 1.9 nM, which was much lower than that of the spectrophotometric method result.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Graphene oxide (GO)-gold nanozymes were prepared as peroxidase mimics. </LI> <LI> The nanozymes exhibited more enhanced activity than GO and AuNP alone. </LI> <LI> The nanozymes were used for an electrochemical H<SUB>2</SUB>O<SUB>2</SUB> sensor. </LI> <LI> The detection limit was much lower than that by colorimetric method. </LI> </UL> </P>