Layered Enzymatic Biosensor Decorated with Prussian Blue Structures for Continuous Electrochemical Glucose Sensing

Continuous glucose monitoring is a pressing need in the management of diabetes mellitus. In this study, we report the development of an innovative electrochemical enzymatic biosensor engineered by immobilizing glucose oxidase on a cystamine-modified ENIG (electroless nickel immersion gold) electrode on a printed circuit board and decorating it with spherical Prussian Blue nanostructures with diameters of 30-90 nm. This multilayered architecture demonstrated enhanced electron transfer efficiency and stable chronoamperometric responses across varying glucose concentrations. The biosensor exhibited immediate, reproducible current changes upon glucose addition, with superior sensitivity at an optimized Prussian Blue concentration of 5 mM. Stability tests conducted over 8 days confirmed consistent performance, but highlighted the need for postanalysis regeneration steps. Furthermore, real-time monitoring experiments in a simulated interstitial fluid environment demonstrated the sensor's ability to maintain functionality over extended immersion periods, delivering rapid, distinct electrochemical signals in response to glucose fluctuations. These results underscore the potential of this biosensor design for future applications in minimally invasive, continuous glucose monitoring systems.