A Highly Efficient Ternary Composite Sensor with a Thiacalix[4]arene-Based Metal−Organic Framework, Spherical Graphite, and Multi-Walled Carbon Nanotubes for Enhanced Electrochemical Sensing of Rutin

Abstract Rutin, as a natural flavonoid, has been used in various medical treatments. Nevertheless, excessive intake of rutin has certain adverse side effects. Thus, it is essential to develop an efficient and accurate method for detecting rutin. In this work, a new metal−organic framework (MOF), namely, [Cd2(L)(BDC)2]·DMF·MeOH (CdLBDC), was prepared with a thiacalix[4]arene-based ligand (L), Cd(II) cations, and 1,3-benzenedicarboxylic acid (H2BDC). Subsequently, spherical graphite (SG), multi-walled carbon nanotubes (MWCNTs), and CdLBDC were ground to yield a family of three-component CdLBDC@MWCNT@SG composites. Under the optimal test conditions, CdLBDC@MWCNT@SG(1:1:1)/GCE exhibited highly sensitive detection of rutin with a low detection limit (0.62 nM). Moreover, CdLBDC@MWCNT@SG(1:1:1)/GCE showed acceptable repeatability, stability, and anti-interference ability during the sensing process of rutin. Remarkably, it was used to determine the rutin content in the actual rutin tablet sample with satisfactory recoveries. Obviously, the synergistic effects between the composites effectively facilitated the electrochemical sensing of rutin. This work manifested that the fabrication of the ternary composite sensors was an effective way to improve the electrochemical detection performances.