Abstract
A versatile approach for the preparation of photoswitchable molecularly imprinted polymers (MIPs) is proposed where the selective recognition and the photoresponsive function are assumed by two different monomers. As a proof of concept, MIP microspheres were synthesized by precipitation polymerization for recognizing terbutylazine, a triazine-type herbicide. Formation of the selective binding sites was based upon H-bonding interactions between the template and the functional monomer methacrylic acid, whereas a polymerizable spiropyran unit was incorporated into the polymer matrix to provide light-controllable characteristics. A trifunctional monomer, trimethylolpropane trimethacrylate, was used as a cross-linker. The imprinted particles exhibited considerable morphological differences compared to their nonimprinted counterparts as observed by scanning electron microscopy. The imprinting effect was confirmed by equilibrium rebinding studies. The photoresponsiveness of the polymer particles was visualized by fluorescence microscopy and further characterized by spectroscopy. The template binding behavior could be regulated by alternating UV and visible light illumination when analyte release and uptake was observed, respectively. Binding isotherms fitted by the Freundlich model revealed the photomodulation of the number of binding sites and their average affinity. This facile synthetic approach may give an attractive starting point to endow currently existing highly selective MIPs with photoswitchable properties, thereby extending the scope of spiropyran-based photoresponsive smart materials.
Highlights
The class of benzospiropyrans has attracted a rapidly increasing attention in the scientific community since their first description by Hirshberg in 1952.1 Spiropyrans can adopt two different structures: a closed, rather nonpolar spiropyran (SP) form, and an open, highly polar merocyanine (MC) form (Figure 1)
We put here forward a new strategy for the preparation of photoswitchable molecularly imprinted polymers (MIPs) where a comonomer, methacrylic acid is mainly responsible for the selective recognition of the template while photochromic spiropyran monomers ensure the photocontrolled template binding and release
We demonstrated the preparation and characterization of photoswitchable molecularly imprinted polymer microspheres based on a novel strategy
Summary
The class of benzospiropyrans has attracted a rapidly increasing attention in the scientific community since their first description by Hirshberg in 1952.1 Spiropyrans can adopt two different structures: a closed, rather nonpolar spiropyran (SP) form, and an open, highly polar merocyanine (MC) form (Figure 1). Methacrylic acid was chosen as an established functional comonomer responsible for the creation of selective recognition sites by interaction with the triazine molecule through multipoint H-bonding.[42] The required relative amounts of spiropyran and MAA as well as the quantity and type of cross-linker were explored by preparing polymers with different composition and testing their template binding ability in equilibrium batch-rebinding assays. The selectivity study was carried out with a mixture of all analytes (50 μM each component) As it can be seen, the selectivity order shows the same trend toward the template and its analogs on the MIP as observed in the individual solution tests albeit the binding is reduced due to the competitive adsorption of the molecules. The presence of photoswitchable binding sites is detectable because in this polymer the photoswitchable spiropyran unit regulates the nonspecific binding
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
