Construction of an Electrochemical Biosensing Platform Based on Hierarchical Mesoporous NiO@N-Doped C Microspheres Coupled with Catalytic Hairpin Assembly.

A critical challenge for improving the detection performance of sensors is building a favorable sensing interface. Herein, an innovative electrochemical biosensing system relying on hierarchical mesoporous NiO@N-doped C microspheres coupled with catalytic hairpin assembly was developed for DNA analysis. In this strategy, the utilization of NiO@N-doped C microspheres and multiwalled carbon nanotubes as electrode materials effectively enhanced the interfacial electron transfer and improved the surface active sites for subsequent reactions. By designing a target-assisted catalytic hairpin assembly, single target DNA could initiate the introduction of multiple signal probes labeled with ferrocene (Fc) onto a working electrode surface. Because the change in the Fc signal is dependent on the amount of target DNA, the resulting electrochemical sensing platform is highly sensitive. Under optimized reaction conditions, this testing platform has a wide linear range for target DNA detection from 100 aM to 100 pM with a detection limit of 45 aM. Furthermore, the platform displayed excellent selectivity, acceptable reproducibility, and long-term stability, highlighting the application potential of this sensing system.