Effect of different carbon allotropes for electrochemical glucose detection

The spread of point-of-care (PoC) glucose sensor technologies is crucial for effective diabetes management. In this context, we present a novel electrochemical biosensing platform that integrates various carbon allotropes-biographene (BGr), zinc oxide (ZnO)-modified multi-walled carbon nanotubes (MWCNT-ZnO), and biologically derived carbon dots (CDs)-in a polyaniline-based matrix (PANI) for glucose detection. The sensing layer was prepared by electropolymerizing aniline in the presence of the individual carbon allotropes and the enzyme glucose oxidase (GOx) on the surface of a screen-printed gold electrode (Au-SPE). The analytical performance of the sensor was evaluated by chronoamperometry (CA) in phosphate-buffered saline (PBS) and glucose-spiked human serum. The morphology and chemical composition of the carbon allotropes were characterized by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Among the sensors tested, the carbon dot (CD)-based sensor demonstrated the best analytical performance, with a limit of detection (LOD) of 1.08 mmol/L and a sensitivity of 0.453 μA per decade of glucose concentration. This covers a linear working range of 1.56 to 75.0 mmol/L, which includes the typical physiological glucose concentration range observed in both healthy individuals and individuals with diabetes. This study aims to improve enzymatic glucose biosensors using fructose-derived carbon dots and PANI to enhance enzyme immobilization, electron transfer, and sensitivity while maintaining low cost and sustainability, offering strong potential for applications in personalized health monitoring and long-term chronic disease management.