MoS2 nanosheets for improving analytical performance of lactate biosensors

Abstract

In this paper, a new 2D lactate electrochemical biosensor was developed. It was based on the incorporation of molybdenum disulfide (MoS2) nanosheets, obtained by an exfoliation method, onto the surface of a glassy carbon (GC) electrode, together with lactate oxidase enzyme (LOx). For the sensor construction, conditions regarding the exfoliation solvent type, as well as both the size and amount of MoS2, were optimized. The biosensor platform (GC/MoS2/LOx) was topographically characterized by atomic force microscopy (AFM) and the charge transfer process occurring at the electrode interface was studied by electrochemical impedance spectroscopy (EIS). The GC/MoS2/LOx biosensor was applied to the determination of lactate in presence of hydroxymethylferrocene (HMF) as a redox mediator. Electrocatalytic effect of the system MoS2/LOx was evaluated by comparing the cyclic voltammetric biosensor response with those obtained for biosensors incorporating only one of the components (MoS2 or LOx) onto the electrode surface. Biosensors containing both components exhibit the best electrocatalytic response. From the calibration curve obtained at +0.30 V, the following analytical parameters were obtained: linear concentration range from 0.056 to 0.77 mM, high sensitivity (6.2 μA mM−1), good detection limit (17 μM) and reproducibility (RSD = 4.7%).