Multi-element doping design of high-efficient carbocatalyst for electrochemical sensing of cancer cells

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Carbon-based electrocatalysts have aroused tremendous research interest owing to their high electrochemical activity, excellent durability and low cost. In this work, we report a well-controlled one-step strategy for the synthesis of a multi-element co-doped carbocatalyst represented by N and S dual-doped graphene (NSG) via annealing microwave exfoliated graphene with ammonium thiocyanate, and explore its application in electrochemical sensing system for sensitive detection of cancer biomarker in live cancer cells. Notably, the active sites of NSG for electrocatalysis have been proposed by the density functional theory calculations. Benefited from the synergistic effect of multi elements co-doping in graphene, the resultant carbocatalyst demonstrates high electrocatalytic activity, large electroactive surface area, good durability, and low toxicity. When used in electrochemical non-enzymatic biosensor for detection of a potential cancer biomarker, i.e., hydrogen peroxide (H2O2), the NSG modified electrode exhibits good sensing performances including a high sensitivity of 0.266 mA cm−2 mM-1, a linear range up to 1.7 mM, a detection limit down to 1 μM (S/N = 3) as well as good selectivity, reproducibility, stability and excellent biocompatibility. For real-time tracking H2O2 secreted from live cancer cells, the NSG modified electrode demonstrations different amperometric current responses that vary from the cell types and the cell survival states with or without chemotherapy treatment. All those features make NSG a promising carbocatalyst in electrochemical sensing system for the pathological diagnosis of cancer, as well as evaluating the pharmacokinetics and therapeutic efficacy in the treatment of cancers.