Facile fabrication of electrochemical sensor based on novel core-shell PPy@ZIF-8 structures: enhanced charge collection for quercetin in human plasma samples

Herein, a novel core-shell structure composite with traditional conducting polymer, polypyrrole (PPy) as its core and zeolitic imidazolate framework-8 (ZIF-8) shell structure was successfully prepared. Thanks to the advantages over electrocatalytic surface provided by ZIF-8 shell and a charge collector given by PPy, the obtained core/shell-structured PPy@ZIF-8 composite displayed an excellent electrocatalytic performance towards quercetin (QR) determination. Under the optimized experimental condition, the differential pulse voltammetry (DPV) peak current signals depend linearly on QR concentration in the range of 0.01–7.0 μmol ⋅ L −1 and 7.0–150 μmol ⋅ L −1 with a low detection limit of 7 nmol ⋅ L −1 . Furthermore, the proposed electrochemical sensor also exhibited good sensitivity, excellent selectivity with reasonable reproducibility and stability during the detection of quantitative QR. A satisfactory performance was observed when this novel sensor was applied to detect QR in human plasma samples with recoveries of 99.1–102.6% and R.S.D. (n = 3) < 3.2%. Thus, the current study provides a new and efficient electrocatalyst for designing QR electrochemical sensor based on conductive conjugated polymer/MOFs heterostructure.