Layered MoS2–graphene composites for biosensor applications with sensitive electrochemical performance

Abstract

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 (k_s) 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.