Layered MoS2–graphene composites for biosensor applications with sensitive electrochemical performance†
This work describes that layered MoS2–graphene composites were assembled on the electrode surface with myoglobin (Mb) and formed a new sensitive biosensor. UV-vis spectroscopy demonstrated that Mb within layered Mb/MoS2–graphene/Nafion films retained its secondary structure similar to its native states. Effective direct electron transfer of Mb was realized with the presence of a pair of well defined and nearly reversible peaks at about −0.38 V vs. saturated calomel electrode (SCE) in pH 7.0 buffers. The electron transfer rate constant (ks) obtained by fitting the data of square wave voltammograms (SWVs) using nonlinear regression analysis was about 60.0 s−1. And the novel biosensor exhibited excellent catalytic performance for various substrates, such as hydrogen peroxide (H2O2) with a detection limit of 1.25 μM and a linear range of 6.25–225 μM and sodium nitrite (NaNO2) in the concentration range from 1.25 to 12.5 mM with a detection limit of 0.125 mM.