Abstract
This paper presents the fabrication of a molecularly imprinted, polymer-based disposable electrochemical sensor for paraoxon (PO) determination. The sensor was based on a screen-printed carbon electrode (SPCE) modified with a surface molecularly imprinted poly (p-aminothiophenol) (PATP)/gold nanoparticles (AuNPs) composite film, which consisted of a PATP outer layer and an AuNPs inner layer. We report a novel strategy, combining surface molecularly imprinting and self-assembly directed electro-polymerization with high densely imprinting PO molecules in the PATP/AuNPs film. Firstly, AuNPs were in situ electrodeposited at the electrode surface, and then assembled with electropolmerizable functional monomer p-aminothiophenol (ATP). Subsequently, PO molecules were assembled onto the ATP monolayer-modified AuNPs, forming a basis of surface molecular imprinting. After that, replenished PO molecules were embedded in the PATP/AuNPs film by PO and the ATP molecular self-assembly directed electro-polymerization in the polymerization precursor mixture. The resulting imprinted PATP/AuNPs/SPCE possesses high sensitivity, affinity, and selectivity toward PO, with a low detection limit of 1 × 10−9 M. The proposed sensor was successfully applied for the determination of PO in fruit and vegetables, giving satisfactory recoveries. The strategy reported herein can be further expected to fabricate various molecular imprinted sensors for the determination of other pesticide residuals.
Highlights
Neurotoxic organophosphates, such as paraoxon (PO), are widely used as persistent pesticides and nerve agents, and are responsible for a number of poisonings
Polymers 2017, 9, 359 organophosphates in the past decade, including liquid or gas chromatography, often coupled to mass spectrometry [6,7] and biological methods, such as immunoassay [8] and enzyme catalysis of organophosphates hydrolysis [9], or inhibition of cholinesterase activity [10]. These different analytical protocols suffer from time-consuming sample pretreatments, poor specificity, long analysis time intervals, complex analytical protocols, expensive instruments, and, potable and fast online tests are impractical
ATP was chosen to act as the polymerizable functional monomer for preparing the PO imprinted would selectively concentrate PO at the electrode surface using hydrogen bonds and π-donorpolymer films
Summary
Neurotoxic organophosphates, such as paraoxon (PO), are widely used as persistent pesticides and nerve agents, and are responsible for a number of poisonings. Polymers 2017, 9, 359 organophosphates in the past decade, including liquid or gas chromatography, often coupled to mass spectrometry [6,7] and biological methods, such as immunoassay [8] and enzyme catalysis of organophosphates hydrolysis [9], or inhibition of cholinesterase activity [10]. Sensitive, these different analytical protocols suffer from time-consuming sample pretreatments, poor specificity, long analysis time intervals, complex analytical protocols, expensive instruments, and, potable and fast online tests are impractical. As an alternative approach—molecularly imprinted polymers (MIPs) that exhibit high selectivity and affinity to the predetermined specific species—are experiencing fast research growth, and have been applied as the sensor recognition element for organophosphates determination [11,12,13]
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