Rational Design of Molecularly Imprinted Polymers Using Quaternary Ammonium Cations for Glyphosate Detection.

Mashaalah Zarejousheghani,Parvaneh Rahimi,Stefan Zimmermann,Yvonne Joseph,Hendrik Wollmerstaedt,Helko Borsdorf,Alaa Jaafar

doi:10.3390/s21010296

Abstract

Molecularly imprinted polymers have emerged as cost-effective and rugged artificial selective sorbents for combination with different sensors. In this study, quaternary ammonium cations, as functional monomers, were systematically evaluated to design imprinted polymers for glyphosate as an important model compound for electrically charged and highly water-soluble chemical compounds. To this aim, a small pool of monomers were used including (3-acrylamidopropyl)trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, and diallyldimethylammonium chloride. The simultaneous interactions between three positively charged monomers and glyphosate were preliminary evaluated using statistical design of the experiment method. Afterwards, different polymers were synthesized at the gold surface of the quartz crystal microbalance sensor using optimized and not optimized glyphosate-monomers ratios. All synthesized polymers were characterized using atomic force microscopy, contact angle, Fourier-transform infrared, and X-ray photoelectron spectroscopy. Evaluated functional monomers showed promise as highly efficient functional monomers, when they are used together and at the optimized ratio, as predicted by the statistical method. Obtained results from the modified sensors were used to develop a simple model describing the binding characteristics at the surface of the different synthesized polymers. This model helps to develop new synthesis strategies for rational design of the highly selective imprinted polymers and to use as a sensing platform for water soluble and polar targets.

Highlights

Glyphosate (N-(phosphonomethyl)glycine), as the most heavily used herbicide in the world, is nowadays recognized as a suspected human carcinogen and is blamed for the death of insects
We believe that quaternary ammonium cations containing the vinyl group are among the most efficient and practical functional monomers, which could enable synthesizing selective imprinted polymers for negatively charged target molecules e.g., glyphosate
The results clearly show that Molecularly imprinted polymers (MIPs) and NIP differences are increased at lower concentrations, which prove the presence of recognition sites for glyphosate within the MIP-B polymer matrix

Summary

Introduction

Glyphosate (N-(phosphonomethyl)glycine), as the most heavily used herbicide in the world, is nowadays recognized as a suspected human carcinogen and is blamed for the death of insects. The surface plasmon resonance sensor was modified with different nanocomposites including chitosan/zinc oxide This modified sensor enabled sensitive detection of glyphosate. For glyphosate as a target molecule, different imprinted polymers were developed for direct detection (sensors) [20,21,22,23,24,25,26,27] or sample-preparation [28,29,30] purposes. We believe that quaternary ammonium cations containing the vinyl group are among the most efficient and practical functional monomers, which could enable synthesizing selective imprinted polymers for negatively charged target molecules e.g., glyphosate. Afterwards, polymers were synthesized on the gold electrodes of quartz crystal microbalance sensors [40] using different template-functional monomers ratios (including optimized ratio).

Materials and Methods

1.15 Gradient elution

Results and Discussion

Polymerization and Characterization

Porogen

Conclusions