Abstract

This work describes the preparation of molecularly imprinted polymer (MIP)-modified core/shell CdTe0.5S0.5/ZnS quantum dots (QDs). The QDs@MIP particles were used for the selective and sensitive detection of dopamine (DA). Acrylamide, which is able to form hydrogen bonds with DA, and ethylene glycol dimethylacrylate (EGDMA) as cross-linker were used for the preparation of the MIP. Highly cross-linked polymer particles with sizes up to 1 µm containing the dots were obtained after the polymerization. After the removal of the DA template, MIP-modified QDs (QDs@MIP) exhibit a high photoluminescence (PL) with an intensity similar to that of QDs embedded in the nonimprinted polymer (NIP). A linear PL decrease was observed upon addition of DA to QDs@MIP and the PL response was in the linear ranges from 2.63 µM to 26.30 µM with a limit of detection of 6.6 nM. The PL intensity of QDs@MIP was quenched selectively by DA. The QDs@MIP particles developed in this work are easily prepared and of low cost and are therefore of high interest for the sensitive and selective detection of DA in biological samples.

Highlights

  • 2-(3,4-Dihydrophenyl)ethylamine, called dopamine (DA), is a member of the catecholamine family

  • Quantum dots (QDs)@molecularly imprinted polymer (MIP) particles were prepared by K2S2O8-mediated copolymerization of acrylamide and ethylene glycol dimethylacrylate (EGDMA) in the presence of the QDs and DA (Scheme 1)

  • QDs@MIP microparticles were efficiently prepared from MPA-capped CdTe0.5S0.5/ZnS QDs, acrylamide, and EGDMA and used as recognition material for the detection of DA

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Summary

Introduction

2-(3,4-Dihydrophenyl)ethylamine, called dopamine (DA), is a member of the catecholamine family. A variety of methods have been implemented to detect DA including chemiluminescence [6,7], electrochemistry [8], colorimetry [9,10], liquid chromatography or capillary electrophoresis [11], and fluorescence spectroscopy [12,13,14,15,16] Each of these methods exhibits advantages and drawbacks. The molecular imprinting process is based on the synthesis of a polymer in the presence of a template, the target molecule, which allows the introduction of molecular recognition cavities in the polymer network These cavities are specific in size and shape and exhibit high substrate recognition ability. We demonstrate that the prepared QDs@MIP composite exhibits a high ability to selectively detect DA over other common molecules in the cell, including amino acids, peptides, proteins, vitamins, ions, and other neurotransmitters. It should be mentioned that the acrylamide/acrylate MIP surrounding CdTe0.5S0.5/ZnS QDs is prepared from readily available, air-stable, and low-cost monomers, which is a major advantage compared to QDs@MIP particles developed to date for the detection of DA

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