One step synthesis of AuNPs@MoS 2 -QDs composite as a robust peroxidase- mimetic for instant unaided eye detection of glucose in serum, saliva and tear

A graphene analogous of transition metal dichalcogenides, mainly molybdenum disulfide (MoS2), have recently attracted wide attention due to its catalytic and electrical properties. Herein, we report a simple one step synthesis of gold nanoparticles (AuNPs) decorated over MoS2 quantum dots (AuNPs@MoS2-QDs) as a robust peroxidase- mimetic material. The AuNPs@MoS2-QDs composite catalyzes the peroxidase substrate of 3, 3′, 5,5′-tetramethylbenzidine (TMB) oxidation in the presence of H2O2 to produce a bluish-green colored product. The peroxidase mimetic behavior of AuNPs@MoS2-QDs composite complies with the steady state kinetics and is stable in harsh conditions such as high or low temperature and pH. The developed composite system has been used for sensitive and selective detection of glucose. The developed biosensor shows an excellent detection in dynamic ranges from 1 to 400 μM (R2∼0.996) with the detection limit of 0.068 μM in PBS buffer solution. Low Km value (0.06 mM) of AuNPs@MoS2-QDs has shown strong binding affinity towards substrates along with high values of Vmax (10.6 × 10−6 Ms−1) indicating greater catalytic reaction rate. Further the biosensor is developed as a portable test kit for detection of glucose in biological fluids like serum, tear and saliva utilizing agarose hydrogel as a visual detection platform. Our portable sensing kit shows an excellent response for detection of glucose in real samples compared to the conventional methods.