Abstract

Molecular imprinting technology (MIT) offers an effective technique for efficient separation and enrichment of specific analytes from complicated matrices and has been used for illicit veterinary drug detectionin recent years due to its high selectivity, good chemical stability, and simple preparation. The development of in silico-based approaches has enabled the simulation of molecularly imprinted polymers (MIPs) to facilitate the selection of imprinting conditions such as template, functional monomer, and the best suitable solvent. In this work, using density functional theory (DFT), the molecularly imprinted polymers of clenbuterol and its metabolites were designed by computer-aided at B3LYP/6-31 + G (d, p) level. Screening molecular imprinting components such as functional monomers, cross-linkers, and solvents has been achieved in the computational simulation considerations. The simulation results showed that methacrylic acid (MAA) is the best functional monomer; the optimal imprinting ratio for both clenbuterol (CLB) and its dummy template molecule of phenylephrine (PE) to functional monomer is 1:3, while the optimal imprinting ratio for the two dummy template molecules of CLB’s metabolites is 1:5. Choosin gethyleneglycol dimethacrylate (EDGMA) as a crosslinker and aprotic solvents could increase the selectivity of the molecularly imprinted system. Atoms in Molecules (AIM) topology analysis was applied to investigate the template-monomer complexes bonding situation and helped to explain the nature of the reaction in the imprinting process. These theoretical predictions were also verified by the experimental results and found to be in good agreement with the computational results. The computer-simulated imprinting process compensates for the lack of clarity in the mechanism of the molecular imprinting process, and provides an important reference and direction for developing better recognition pattern towards CLB and its metabolite analytes in swine urine samples at the same time.

Highlights

  • Clenbuterol (C12 H18 CL2 N2 O, CLB), which is used in human and veterinary medicine as a therapeutic drug for the pulmonary disease, is a synthetic β2-adrenoceptor agonist [1]

  • Current detection methods for clenbuterol mainly include enzyme-linked immunoassay (ELISA) [4], gas chromatography coupled with mass spectrometry (GC-MS) [5], high performance liquid chromatography (HPLC) [6], liquid chromatography–mass spectroscopy (LC-MS) [7], surface molecularly imprinted polymers [8], electrochemical analysis [9], capillary electro-phoresis [10], and fluorescence biosensor [11]

  • Considering the poor performance of the combination between acrylic acid (AA) and hydroxymandelic acid (HMA), and methacrylic acid (MAA) has been more commonly used in molecular imprinting, MAA was chosen as the functional monomer

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Summary

Introduction

Clenbuterol (C12 H18 CL2 N2 O, CLB), which is used in human and veterinary medicine as a therapeutic drug for the pulmonary disease, is a synthetic β2-adrenoceptor agonist [1]. With the rapid development of in silico simulation, it is a hot topic in current research to assist in the rational design of MIPs system through computational chemistry [21] and computer simulation plays an important role in determining the optimal functional monomer, optimizing the synthesis conditions of the imprinted substance, and elucidating the mechanism of molecular imprinting recognition [22,23,24]. Phenylephrine (PE) will be employed as a dummy template molecule for CLB, the designed array will be constituted of four sensors based on four high selective molecular imprinted polymers, which can be developed into a robust and cost-effective method suitable for simultaneous detection of CLB and its metabolites

Selection of Functional Monomer
Selection of Functional
Construction of Template-Monomer Complexes
AIM Topology Analysis
Cross-Linking Agent Screening
Selection of Solvent
Selectivity Examination by Computational Simulation
Surface Cleaning of QCM Gold Electrode
Preparation of AIBN-QCM
In Situ Preparation of MIPs
MIP-QCM Performance Test
Theoretical Selection of Functional Monomer
Formation of the Template-Monomer Complexes
The optimal conditions were
Theoretical Selection of Crosslinker
Theoretical
Selectivity Simulation
This is consistent with themonomer judgmentofinCLB the and PE issubsection
Experimental Verification
Conclusions
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