Flexible enzyme-like platform based on a 1-D CeVO4/2-D rGO-MCC heterostructure as sensor for the detection of intracellular superoxide anions

The production of excessive superoxide anions (O2•－) in living cells will induce oxidative stress, leading to mitochondrial dysfunction and further activating pathogenic factors. Therefore, real-time monitoring of O2•－concentration in vivo is of great significance for disease diagnosis, clinical diagnosis and treatment. Herein, as a nanozyme that can functionally mimic superoxide dismutase (SOD) activity, 1 dimensional (1-D) cerium vanadate (CeVO4) nanorods were assembled on 2-D nanosheets of reduced graphene oxide-microcrystalline cellulose (rGO-MCC) composite by a simple hydrothermal method to resemble a novel ternary composite material. The intercalated growth of 1-D CeVO4 nanorods between the 2-D rGO-MCC nanosheets effectively minimized the agglomeration of rGO and facilitated the ion/electron transport. The ternary composite has SOD-like catalytic capability, excellent electrical conductivity, large surface area and plentiful active sites. These properties endowed the constructed sensor with a wider linear range (4.3 nM-28.495 μM and 28.495–71.994 μM), high sensitivity (1.047 μA·μM−1·cm−2 and 0.536 μA·μM−1·cm−2), low detection limit (1.28 nM) and fast response time (3.14 s) for the detection of superoxide anion. Particularly, the ternary composite exhibits extraordinary flexibility and stability, making it an ideal flexible sensing platform for dynamic monitoring O2•－ in living Hela cells. This work proves that the flexible sensing platform has bright application prospects in the measurement of electrophysiological signals derived from mitochondrial oxidative stress-related diseases.