Antifouling properties of carbon quantum dots-based electrochemical sensor as a promising platform for highly sensitive detection of insulin

In this study, for the first time, the performance of carbon quantum dots (CQDs) as a platform in electrochemical detection of insulin at physiological pH is investigated. Electrochemical oxidation of insulin on the surface of a CQDs-modified glassy carbon (GC) electrode is examined using cyclic voltammetry and hydrodynamic amperometry methods. The results show that the oxidation of insulin at the surface of the normal GC electrode leads to the deactivation of the surface after a short period of time, while a stable and amplified insulin oxidation current is observed using the GC/CQDs modified electrode. The amperometric response of the GC/CQDs electrode provide a low detection limit of 2.24 nM, a sensitivity of 0.87 nA/nM and a linear range of 40-200 nM for insulin determination. Based on suitable stability, antifouling properties and increased insulin oxidation current, CQDs can be used as a new platform for electrochemical detection of insulin at physiological pH. In addition, the facile and low-cost method of preparing CQDs against graphene-based materials such as graphene oxide and reduced graphene oxide, can introduce it as a new alternative material in many electrochemical applications.