Ultrasensitive chemiluminescent biosensor for the detection of cholesterol based on synergetic peroxidase-like activity of MoS and graphene quantum dots.

Developing a novel non-enzyme mimetic in biosensors is of great significance. Here, a synergetic peroxidase-like activity was disclosed for mixed MoS quantum dots (MoS QDs) and graphene quantum dots (GQDs). The high catalytic effect of this mixture was studied on the chemiluminescence system. It was observed that the simultaneous presence of MoS QDs and GQDs had a powerful enhancing effect on the chemiluminescence (CL) emission of rhodamine B (RB)-HO reaction. MoS QDs and GQDs mixture (prepared with a ratio of 3:2) showed a superior catalytic activity when compared to each of the constituents. A linear relationship was acquired between the CL emission intensity and HO concentration in the range of 1.5-460nmolL. On the other hand, since the enzymatic oxidation of cholesterol leads to the production of HO; the offered CL system was examined to detect cholesterol after its oxidation by cholesterol oxidase (ChOx) enzyme. Herein, a further improvement was achieved by MoS nanosheets. The MoS nanosheets increased the performance of ChOx in cholesterol oxidation process. The obtained results confirmed a highly selective and sensitive determination of cholesterol concentration in a linear dynamic range of 0.08-300µmolL, with a detection limit (3S) of 35nmolL. The developed method was successfully applied for the detection of cholesterol level in human serum samples.