A new electrochemical sensing strategy for echinacoside based on an original nanocomposite

In this work, a brand new nanocomplex (denoted as MOF-5@PDDA-rGO-Ni) is elaborately designed and successfully synthesized meaning the in-situ assembly of porous-morphology Zn-based MOFs (MOF-5) onto the asprepared PDDA-rGO-Ni (PGN for short) nanocomposites. When this nanocomplex contributes to construct the electrochemical sensor (MOF-5@PGN/GCE), it presents a highly-sensitive response towards echinacoside, and the first measurement for echinacoside by electrochemistry accordingly evolves forward. The crystallization processes are investigated by FT-IR instrument and XRD analysis, as well as micro-morphology of modified materials is visible upon SEM and TEM. Adorably, a novel ratiometric sensor was progressively fabricated by encapsulating methylene blue (MB) molecules into cubic MOF-5 framewoks (MB encased MOF-5@PGN/GCE), and apart from assisting in establishing the analysis method with extreme accuracy and favorable practicality, it dose devote a wider linear scale and a lower detection limit than that MOF-5@PGN/GCE has given out. Drawn from the developed calibration curve using differential pulse voltammetry (DPV) technique, the peak intensity ratio (I-Ech/I-MB) varies linearly with increased echinacoside concentration in the range of 3.0x10(-8) 1.0x10(-6) mol L-1 with limit of detection (LOD) reaching 1.0x10(-8) mol L-1 (S/N = 3). Additionally, the proposed assay method has been employed to detect echinacoside in real sample sliced cistanche with satisfactory results.