Fabrication of hollow ZnO-Co3O4 nanocomposite derived from bimetallic-organic frameworks capped with Pd nanoparticles and MWCNTs for highly sensitive detection of tanshinol drug.

In this work, PdNPs@ZnO-Co3O4 was synthesized via the facile oxidation treatment of bimetallic ZnCo-zeolitic-imidazolate-framework (ZnCo-ZIF) followed by in situ chemical reduction of PdNPs on the surface of the nanocrystals. After combined with MWCNTs, the PdNPs@ZnO-Co3O4-MWCNTs nanocomposites were formed, which were then exploited as novel electrode materials to construct the non-enzyme electrochemical sensors for high-sensitivity detection of tanshinol. Due to the high catalytic activity of multi-metallic PdNPs@ZnO-Co3O4, and the excellent charge transfer property between imidazole groups of the ligands in MOFs and MWCNTs, the obtained sensor exhibited high sensitivity for tanshinol detection under optimum experimental conditions. The sensor shows two well linear relationship between the current and tanshinol concentration in the range of 0.002-0.69 mM (R2 = 0.989) and 0.69-3.75 mM (R2 = 0.994) with the corresponding sensitivity of 59.16 μA mM-1 and 19.08 μA mM-1. And the limit of detection (LOD) was calculated to be 0.019 μM (S/N = 3). Furthermore, with the advantages of good repeatability, stability and selectivity, the fabricated sensor can be successfully applied to measurement of tanshinol in real medicinal liquids samples. Our results would accelerate the applications of MOFs in electrochemical field and provide insights into design of multifunctional non-enzyme sensing materials for various applications in biocatalysis, bioanalysis and drug testing.