Stainless steel 304 needle electrode for precise glucose biosensor with high signal-to-noise ratio

Abstract

While accuracy and precision of human serum glucose measurements play a crucial role in determining treatments targeting glycemic control, electrochemical glucose meters widely used for blood sugar monitoring, have been facing issues of inaccuracy, making their application in medical decision-making difficult. Herein, we report a new amperometric glucose biosensor with extreme precision based on a stainless steel 304 (SS304) needle modified with glucose oxidase (GOx), chitosan, and Nafion. GOx and chitosan are immobilized on the surface of the SS304 needle and then covered with the Nafion layer. We focused on reducing electrochemical background signals and securing high signal-to-noise ratios associated with the electrode material, in contrast to most previous studies focusing on detection sensitivity enhancement. The SS304 needle was employed as a sensing electrode with H2O2, a product of GOx-catalysed oxidation reaction of glucose, owing to its convenient electrical properties with extremely shallow non-faradaic background currents under electrochemical conditions. We confirmed that the SS304 needle immobilized with glucose oxidase shows a distinct increase in current upon the addition of glucose at −0.10 V (vs. a saturated calomel electrode). The amperometric signal from the modified SS304 was specific to the serum glucose level without notable interference. It exhibits a strict linear correlation in the diabetic sugar level of 1–20 mM (y = 0.205x, R2 = 1.000) with an outstanding reproducibility (RSD = 4.4–6.8 %) and long-term storage stability. These results demonstrated that the SS304 electrode possesses great potential for electroanalytical biosensors based on the H2O2 content.