Molecular imprinting technology allows synthesis of polymers with specific recognition ability towards target pollutants, which show potential to selectively remove Highly Toxic Organic Pollutants (HTOPs) in the presence of common organic matrices that are thousands of times more abundant than the targets. This feature article summarizes the current development of molecular imprinting for removing HTOPs from polluted water, with a special emphasis on the application of molecularly imprinted polymers to improve the efficiency of photocatalytic and biological degradation of HTOPs in wastewater.

Molecular imprinted polymer coated photocatalysts were prepared via polymerization of a proper functional monomer in the presence of TiO(2) nanoparticles and target molecules, which was found to promote the selectivity of TiO(2) photocatalysis.

Poor selectivity of titania (TiO2) photocatalysis is unfavorable to photocatalytic removal of highlytoxic low-level organic pollutants in polluted waters in the presence of other less toxic high-level pollutants. A new strategy of increasing this selectivity is the surface modification of TiO2 via coating a thin layer of molecular imprinted polymer (MIP), which provides molecular recognition ability toward the template molecules. By using 2-nitrophenol and 4-nitrophenol as target pollutants, MIP-coated TiO2 photocatalysts were prepared via surface molecular imprinting and were observed to have high activity and selectivity toward the photodegradation of the targets. In the presence of bisphenol A (50 mg L(-1)) as a nontarget pollutant, the apparent rate constant for the photodegradation of the target 2-nitrophenol and 4-nitrophenol (1.8 mg L(-1)) over the corresponding MIP-coated TiO2 was 10.73 x 10(-3) and 7.06 x 10(-3) min(-1), being 2.46 and 4.61 times of that (4.36 x 10(-3) and 1.53 x 10(-3) min(-1)) over neat TiO2, respectively. The enhanced photocatalytic selectivity was increased when the concentration of the target was decreased and/or when the difference in both the chemical structure and molecule size between the target and nontarget molecules was increased. The increased selectivity was mainly attributed to the special interaction between the target molecules and the footprints polymer via the functional groups (-OH and -NO2).

The tendency of bacteria to assemble at oil-water interfaces can be utilized to create microbial recognition sites on the surface of polymer beads. In this work, two different groups of bacteria were first treated with acryloyl-functionalized chitosan and then used to stabilize an oil-in-water emulsion composed of cross-linking monomers that were dispersed in aqueous buffer. Polymerization of the oil phase followed by removal of the bacterial template resulted in well-defined polymer beads bearing bacterial imprints. Chemical passivation of chitosan and cell displacement assays indicate that the bacterial recognition on the polymer beads was dependent on the nature of the pre-polymer and the target bacteria. The functional materials for microbial recognition show great potential for constructing cell-cell communication networks, biosensors, and new platforms for testing antibiotic drugs.

A new interfacial nano and molecular imprinting approach is developed to prepare spherical molecularly imprinted polymers with well-controlled hierarchical structures. This method is based on Pickering emulsion polymerization using template-modified colloidal particles. The interfacial imprinting is carried out in particle-stabilized oil-in-water emulsions, where the molecular template is presented on the surface of silica nanoparticles during the polymerization of the monomer phase. After polymerization, the template-modified silica nanoparticles are removed from the new spherical particles to leave tiny indentations decorated with molecularly imprinted sites. The imprinted microspheres prepared using the new interfacial nano and molecular imprinting have very interesting features: a well-controlled hierarchical structure composed of large pores decorated with easily accessible molecular binding sites, group selectivity toward a series of chemicals having a common structural moiety (epitopes), and a hydrophilic surface that enables the MIPs to be used under aqueous conditions.

No abstract

Prognostic level III.

Molecularly imprinted polymer microspheres were synthesized by Pickering emulsion polymerization. Fluorescence spectroscopic investigations provided insights into the template recognition in water.