Multishell Au@Ag@SiO 2 nanorods embedded into a molecularly imprinted polymer as electrochemical sensing platform for qu
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ORIGINAL PAPER
Multishell Au@Ag@SiO2 nanorods embedded into a molecularly imprinted polymer as electrochemical sensing platform for quantification of theobromine Tian Gan 1,2
&
Jiebin Li 1 & Liping Xu 1 & Shufeng Guo 1 & Aixia Zhao 1 & Junyong Sun 1
Received: 14 December 2019 / Accepted: 19 April 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract A highly uniform and monodisperse silica-encapsulated Au@Ag multilayered core-shell nanorods (~ 80 nm in length) has been prepared with excellent electrocatalytic properties. Using the Au@Ag@SiO2 nanoassemblies to substantially enhance the sensitivity and the sol-gel molecularly imprinted polymer (MIP) with imprinted cavities to present special molecular recognition sites, a novel electrochemical sensing platform was rationally designed, fabricated, and tested for efficient theobromine (THB) quantification. The formation of final Au@Ag@SiO2@MIP was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The performance of the Au@Ag@SiO2@MIP modified electrode was evaluated by differential pulse voltammetry with the changes in peak current of hexacyanoferrate redox probe measured at a working potential of 0.2 V (vs. saturated calomel electrode) as determination signal. Under optimal conditions, the quantitation of THB was attained in a broad linear range from 10 nM to 100 μM with a detection limit of 8.0 nM. The selectivity of Au@Ag@SiO2@MIP was examined according to its recognition to THB and the interferents. Finally, the sensing platform was successfully applied to extract and determine THB from food, biological, and environmental samples with acceptable recoveries (92.20–107.1%) and relative standard deviation < 4%. The propsed sensor provides a robust means for monitoring alkaloids in complex matrices and a promising opportunity to develop sensitive and selective electrode materials with good reusability. Keywords Au@Ag@SiO 2 . Bimetallic core-shell nanoparticles . Molecularly imprinted polymer . Theobromine . Electrochemical determination
Introduction Theobromine (THB), known as 3,7-dimethyl xanthine, is one of the important metabolites of caffeine and the major dimethylxanthine alkaloid present in high concentrations in Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-020-04288-6) contains supplementary material, which is available to authorized users. * Tian Gan [email protected] 1
College of Chemistry and Chemical Engineering, Institute for Conservation and Utilization of Agro−Bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
2
First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China
cocoa plant [1]. THB has attracted considerable attention for many years because it can cause various biological and physiological activities. It shares in common with theophylline and caffeine in pharmacological
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