An alternative electron transfer process for selective detection of glucose in blood serum

Here, we demonstrate efficient electrochemical detection of glucose in blood serum using CdS nanoribbons coated indium Tin Oxide (ITO) electrode. Main appeal of this work is to establish an alternative electron transfer (AET) process by dissolving the glucose oxidase (GOX) enzyme in the electrolyte instead of direct immobilization on the electrode's surface to demonstrate better performance of glucose sensing. In this context, we developed an experimental strategy through amperometric detection of hydrogen peroxide (H₂O₂) which is an intermediate reaction product of glucose oxidation by GOX present in the buffer solution. Therefore, we separately performed electrochemical detection of H₂O₂ by CdS nanoribbons in buffer solution followed by glucose detection with the same electrode by dissolving GOX in the buffer solution. The linear range of amperometric current measured with the same concentration of both H₂O₂ and glucose overlaps with each other which clearly proves that electrocatalytic reduction of both the analytes occur at the same rate on the CdS surface. Our studies reveal that dissolved GOX in buffer solution have a better performance than the GOX immobilized electrode. Furthermore, chronoamperometric detection of glucose in actual blood serum sample was performed and our results show even better performance than the commercially available glucometer.