Fe-doped two-dimensional graphite carbon nitride: An effective nanozymetic catalyst for electrochemical detection of cell-released H2O2

In this work, a simple one-step pyrolysis process was designed to synthesize Fe-doped graphite carbon nitride (Fe–C 3 N 4 ) nanosheets with FeCl 3 as Fe source. The resulted samples were characterized by various characterization techniques, and the results showed that Fe species might form Fe–N bonds with N atoms of C 3 N 4 , which was similar to the iron (Ⅲ) porphyrin active center of horseradish peroxidase. Then Fe–C 3 N 4 nanosheet was further mixed with carbon nanotube (CNT) to obtain Fe–C 3 N 4 @CNT nanocomposite, which was further modified on the self-made flexible printed electrode (PE) to construct the flexible working electrode. Fe–C 3 N 4 nanosheets show good catalytic activity for H 2 O 2 and the introduction of CNT can effectively improve the electron transfer efficiency at the modified electrode interface. By combining with wireless portable electrochemical workstation, the sensor shows a wider detection range (10.0 μmol/L–20.0 mmol/L) and a lower limit of detection (0.38 μmol/L, S/N = 3) for the H 2 O 2 analysis. Furthermore, the sensor can be applied to the real time and in-situ analysis of H 2 O 2 secreted from live cells. In word, this self-supported sensing electrode shows great potential applications in monitoring the pathological and physiological dynamics of cancer cells.