Fabrication and Sensing Properties of Fibrous-Like Chlorophenoxy Herbicide-Imprinted Polymeric Matrix via Microcontact Printing.

In this study, a novel fibrous-like molecularly imprinted polymer film (F-MIP)-based QCM sensor was developed for the detection of methyl-4-chlorophenoxyacetic acid (MCPA). An electrospinning process was used to create a poly(N-tert-butylacrylamide) (TBAm) nanofiber membrane that would be used as the master mold for the creation of a polydimethylsiloxane (PDMS) replica mold. Further, this replicated mold was used for the fabrication of an F-MIP film on a gold-coated quartz crystal (QC) substrate via microcontact imprinting. One of the well-known functional monomers, methacrylic acid (MAA), and ethylene glycol dimethacrylate were used as functional monomer and crosslinker for the F-MIP films, respectively. The imprinted polymer network from the MIP precursor solution including the MCPA template was formed via photopolymerization during mold contact on the QC substrate. The diameter of the poly(TBAm) nanofiber used as a membrane mold controlled the fibrous morphology on the MIP film, which was investigated using field emission scanning electron microscopy. The binding behaviors of MCPA on the MIP-QCM sensor were evaluated by measuring the change in resonant frequency (Δf) values of F-MIP/NIP films with analyte adsorption in MCPA solution with a concentration range of 0.02–200 ng/mL. Furthermore, the sensing responses on the film were used to calculate the limit of detection, the limit of qualification, and the imprinting factor. The selectivity of the films was determined by comparing their sensing responses to similar herbicides. Despite the effect of nonspecific adsorption on both films due to the functional groups on MAA monomer, the imprinted film exhibited higher sensing properties and amplified sensing responses due to the fibrous-like MIP film's increased surface area. As a result, this sensor is expected to be a better option than another analytical method for detecting herbicides. [ABSTRACT FROM AUTHOR]