ABSTRACT
Electrochemical sensors actually involve an electrocatalytic process in efficient and selective energy conversion. In this work, we use different components to innovatively produce a core@cage material, in which the outer cage, iron phosphate, offers a high electrocatalytic ability to electrochemically oxidize NO, while the inner material, cuprous oxide, could absorb the intermediary HO- ions to kinetically promote NO oxidation for fast electron transfer, resulting in a strong synergistic effect. The unique core@cage structure also increases the active surface area and provides plenty of channels via the porous cage for significantly enhanced mass transport. The as-prepared core@cage NO sensor shows a high sensitivity of 326.09 µA cm-2 µM-1, which is the highest among the reported non-noble metal-based NO biosensors based on the electrooxidation scheme. A free-standing flexible NO sensor was further fabricated with the material for the in situ detection of NO released from cancer cells, demonstrating a low detection limit (0.45 nM) and a fast response time (0.8 s). This work holds great promise for its practical applications in the diagnosis or research of complicated biological processes, especially in real-time in situ detection approaches.
