Fabrication of pioneering 3D sakura-shaped metal-organic coordination polymers Cu@L-Glu phenomenal for signal amplification in highly sensitive detection of zearalenone

Abstract

Low molecular weight pollutants from foods have aroused global attention due to their toxicity after long-time exposure. There is an increased demand for appropriate methods to detect these pollutants in foods. In this study, a brand-new type of nano metal–organic coordination polymers (MOCPs) nanocarriers (3D sakura-shaped copper (II) ions@L-glutamic acid (L-Glu)) has been first synthesized. We herein demonstrate a facile chelated method that allows the combination of copper (II) ions and L-Glu. A series of controlled experiments have revealed that the reaction time and the ratio of reactants played the crucial roles in affecting the morphology of the final product. 3D sakura-shaped Cu@L-Glu combined with palladium-platinum nanoparticle (Pd-PtNPs) to obtain Cu@L-Glu/Pd-PtNPs acting as the signal tag, which applied in electrochemical aptasensor for ultrasensitive detection of zearalenone (ZEN). A glassy carbon electrode was first modified with spherical Au-PANI-Au nanohybrids to enhance the conductivity and immobilize more amino modified ZEN aptamer. Cu@L-Glu/Pd-PtNPs were labeled with Complementary DNA (partial matching with ZEN aptamer) to form bioconjugates for signal amplification. After the hybridization reaction of ZEN aptamer and the bioconjugates, a significant electrochemical signal from the catalysis of H2O2 by Cu@L-Glu/Pd-PtNPs can be observed. ZEN competed with bioconjugates for binding to ZEN aptamer, resulting in decreased the electrochemical signal. Chronoamperometry was applied to record the final electrochemical signals. Under optimal conditions, the electrochemical aptasensor exhibited desirable sensitive detection of ZEN with a wide linearity ranging from 1 fg/mL to 100 ng/mL and a relatively low detection limit of 0.45 fg/mL (S/N = 3). Furthermore, the proposed electrochemical aptasensor shows excellent selectivity to the ZEN in the presence of possible interfering substances, and has potential application for ZEN detection in food samples.