A direct electrochemical biosensor for rapid glucose detection based on nitrogen-doped carbon nanocages

Given the increasing number of diabetic patients, rapid and accurate detection of glucose in body fluids is critical. This study developed a direct electrochemical biosensor for glucose based on nitrogen-doped carbon nanocages (NCNCs). NCNCs possess a large specific surface area of 1395 m²·g⁻¹, a high N atomic content of 9.37% and good biocompatibility, which is favorable for enzyme loading and electron transfer. The surface average concentration of electroactive glucose oxidase on NCNCs was 2.82 × 10^–10 mol·cm⁻². The NCNC-based direct electrochemical biosensor exhibited a high sensitivity of 13.7 μA·(mmol·L⁻¹)⁻¹·cm⁻², rapid response time of 5 s and an impressive electron-transfer-rate constant (k_s) of 1.87 s⁻¹. Furthermore, we investigated an NCNC-based direct electron transfer (DET) biosensor for sweat glucose detection, which demonstrated tremendous promise for non-invasive wearable diabetes diagnosis.