The widespread use of antibiotics in livestock farming leads to trace residues in food products and wastewater, potentially entailing antimicrobial resistance in food-borne pathogens. The determination of antibiotics in aqueous environments and foodstuff is thus of major concern.
Analytical assays based on molecularly imprinted polymers (MIPs) have emerged as a valuable tool in this field due to the low production costs, stability, format adaptability and the possibility to imprint and thus their ability to recognize a wide variety of target analytes. With regard to optical sensing technologies, however, MIPs have only been used in considerably few applications, especially in fluorescence sensors. This limitation is basically due to the fact that the incorporation of a fluorescently responding moiety into a polymer matrix is challenging. One way to overcome this limitation is to use tailor-made fluorescent indicator monomers for direct transfer of the binding event into an optical signal. If such a monomer is integrated into a thin MIP-shell on microspheres such core/shell particles can be readily used in advanced multiplexing sensory fiber-optic microarrays.
Here, we propose such a fiber-optic microarray based on fluorescent MIP microspheres for antibiotics. The binding behavior and the selectivity of a microarray using these MIP were examined and compared with a non-imprinted polymer (NIP) control, employing the target molecules and other structurally closely related antibiotics.
As the interest in rapid and sensitive detection methods is growing, molecularly imprinted polymers (MIPs) are increasingly considered as an alternative to bio-macromolecular recognition units such as antibodies or enzymes due to their facilely tailorable selectivity towards certain analytes or a group of structurally related species. The low production costs, stability, robustness and format adaptability of MIPs combined with the possibility to imprint and thus their ability to recognize a wide variety of target analytes can be potentially useful in chemical sensor applications.[1] With regard to optical sensing technologies, however, MIPs have only been used in considerably few applications, especially in fluorescence sensors. This limitation is basically due to the fact that the incorporation of a fluorescently responding moiety into a polymer matrix is a challenge. One way to overcome this limitation is to use tailor-made fluorescent indicator monomers and thin MIP-shells on silica particles.[2]
Here, we present silica sensor particles with a thin MIP layer which was grown onto the silica surface via reversible addition-fragmentation chain transfer (RAFT) polymerization. The homogeneous MIP shell contains fluorescent phenoxazine-urea monomers as signal generation elements. The carboxylate salts of the antibiotic ampicillin (AMPI) and the herbicide 2,4 dichlorophenoxyacetic acid (2,4-D) were used as templates in those studies. In this case, hydrogen bonds are formed between the urea group of the fluorescent monomer and the carboxylate group of the template. To investigate the binding behavior of the MIPs and the control non-imprinted polymer (NIP) particles in terms of discrimination and imprinting factor, titration experiments with AMPI and 2,4-D salts were performed directly in organic solution. In order to study the detection possibilities in aqueous solution, a simple phase-transfer assay using fluorescence spectroscopy was investigated for both analytes.
The widespread use of antibiotics in livestock farming leads to trace residues in food products and wastewater, potentially entailing antimicrobial resistance in food-borne pathogens. The determination of antibiotics in aqueous environments and foodstuff is thus of major concern.
We have been developing optical sensors based on molecularly imprinted polymers (MIPs) due to the low production costs, stability, format adaptability and the possibility to imprint and thus their ability to recognize a wide variety of target analytes. As a fluorescently responding moiety in the polymer matrix a tailor-made fluorescent indicator cross-linker for direct transfer of the binding event into an optical signal was used. If such a cross-linker is integrated into a thin MIP-shell on microspheres such core/shell particles can be readily used in advanced multiplexing sensory fiber-optic microarrays.
Here, we propose such a fiber-optic microarray based on fluorescent MIP microspheres for antibiotics. The binding behavior and the selectivity of a microarray using these silica core/MIP shell beads were examined and compared with a non-imprinted polymer (NIP) control, employing the target molecules and other structurally closely related antibiotics.