Abstract

Tiny changes in the mass of the sensor in a quartz crystal microbalance with dissipation monitoring (QCM-D) can be observed. However, the lack of specificity for target species has hindered the use of QCM-D. Here, molecularly imprinted polymers (MIPs) were used to modify a QCM-D sensor to provide specificity. The MIPs were formed in the presence of sodium dodecyl benzene sulfonate. Imprinted layers on Fe3O4 nanoparticles were formed using pyrrole as the functional monomer and cross-linker and methylene blue (MB) as a template. The MIPs produced were then attached to the surface of a QCM-D sensor. The MIPs-coated QCM-D sensor could recognize MB and gave a linear response in the concentration range 25 to 1.5 × 102 µg/L and a detection limit of 1.4 µg/L. The QCM-D sensor was selective for MB over structural analogs. The MIPs-coated QCM-D sensor was successfully used to detect MB in river water and seawater samples, and the recoveries were good. This is the first time MB has been detected using a QCM-D sensor. Mass is an intrinsic property of matter, so this method could easily be extended to other target species by using different MIPs.

Highlights

  • A quartz crystal microbalance with dissipation monitoring (QCM-D) sensor is a simple, very versatile, and sensitive sensor for studying processes that occur on surfaces or within thin films [1]

  • The method used to prepare the molecularly imprinted polymers (MIPs)-coated QCM-D sensors is shown in Scheme 1

  • sodium dodecyl benzene sulfonate (SDBS) and the target analyte and because the SDBS increased the thickness of the ppy-imprinted layer, which allowed many more imprinted cavities to occur in the MIPs and made the system more specific to the target analyte. These results indicated that the presence of SDBS improved the adsorption capacities of the MIPs and non-imprinted polymers (NIPs)

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Summary

Introduction

A quartz crystal microbalance with dissipation monitoring (QCM-D) sensor is a simple, very versatile, and sensitive sensor for studying processes that occur on surfaces or within thin films [1]. Mass is a fundamental property of any target analyte, and QCM systems detect analytes by mass, meaning labels are not required [2]. QCM has been used to perform analyses of food, environmental media, and biomedical media [2,3,4]. The complex natures of these sample matrices mean that it is important to develop selective and specific methods for determining target analytes in such matrices. QCM sensors are not selective or specific. This precludes the use of QCM sensors for many applications

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