Multilayer Films with Nanocontainers: Redox‐Controlled Reversible Encapsulation of Guest Molecules

Stable multilayer films with cucurbit[8]uril have been fabricated on the basis of the alternating layer‐by‐layer assembly of a novel side‐chain pseudopolyrotaxane and a photoreactive polyanion. The as‐prepared multilayer films exhibit good properties as surface‐imprinted multilayers, because cucurbit[8]uril molecules that are locked inside the multilayers can act as nanocontainers with specific binding to certain guest molecules, and the loading and release of the guest is redox‐controllable and reversible.     

Efficient one‐pot synthesis of water‐compatible and photoresponsive molecularly imprinted polymer nanoparticles by facile RAFT precipitation polymerization

A facile, general, and highly efficient one‐pot approach to obtain azobenzene (azo)‐containing molecularly imprinted polymer (MIP) nanoparticles with photoresponsive template binding and release properties in aqueous media is described, which involves the combined use of hydrophilic macromolecular chain transfer agent‐mediated reversible addition‐fragmentation chain transfer precipitation polymerization and easily available water‐insoluble azo functional monomers. The resulting azo‐containing MIPs were characterized with dynamic laser scattering (DLS), SEM, FTIR, static contact angle and water dispersion studies, and equilibrium binding experiments. They have proven to be nanoparticles (their diameters being around 104–397 nm, as determined by DLS in methanol) with surface‐grafted hydrophilic polymer brushes and exhibit excellent pure water‐compatible template binding properties. Moreover, obvious photoregulated template binding behaviors were observed for such azo‐containing MIP nanoparticles, which led to their largely accelerated template release in the aqueous media under the UV light irradiation. Furthermore, the general applicability of the strategy was also demonstrated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1941–1952     

A Bait-and-Switch Method for the Construction of Artificial Esterases for Substrate-Selective Hydrolysis

Outcomes of chemical reactions are generally dominated by the intrinsic reactivities of reaction partners, but enzymes frequently override such constraints to transform less reactive molecules in the presence of more reactive ones. Despite the attractiveness of such catalysis, it is difficult to build synthetic catalysts with these features. Micellar imprinting is a powerful method to create template-complementary binding sites inside protein-sized water-soluble nanoparticles. When a photocleavable functional monomer was used to bind two phosphonate/phosphate templates as transition-state analogues, active sites with predetermined size and shape were formed inside doubly cross-linked micelles through molecular imprinting. Postmodification replaced the binding group with a catalytic pyridyl group, forming highly selective artificial esterases. The catalysts displayed enzyme-like kinetics and turnover numbers that were in the hundreds. The selectivity of the catalysts, derived from the substrate-complementary imprinted active sites, enabled transformation of less reactive esters in the presence of more reactive ones.     

Combined protein A imprinting and cryogelation for production of spherical affinity material

Cryogels have been demonstrated to be efficient when applied for protein isolation. Owing to their macroporous structure, cryogels can also be used for treating particle‐containing material, e.g. cell homogenates. Another challenging development in protein purification technology is the use of molecularly imprinted polymers (MIPs). These MIPs are robust and can be used repeatedly. The paper presents a new technology that combine the formation of cryogel beads concomitantly with making imprints of a protein. Protein A was chosen as the print molecule which was also be the target in the purification step. The present paper describes a new method to produce protein‐imprinted cryogel beads. The protein‐imprinted material was characterized and the separation properties were evaluated with regard to both the target protein and whole cells with target protein exposed on the cell surface. The maximum protein A adsorption was 18.1 mg/g of wet cryogel beads. The selectivity coefficient of protein A‐imprinted cryogel beads for protein A was 5.44 and 12.56 times greater than for the Fc fragment of IgG and protein G, respectively.     

Molecular signal suppression by in situ microextraction in nuclear magnetic resonance spectroscopy

The detailed characterization of complex mixtures by NMR is often hampered by the presence of signals from uninformative compounds, the resonances of which overlap with those of the molecules of interest. We provide here a proof of principle for an approach to NMR signal suppression in complex samples using Molecularly Imprinted Polymers (MIPS). Addition of a few milligrams of polymer to a solution traps the target molecule in typical micromolar to millimolar concentration, thus achieving in situ signal suppression, without altering any other spectral features. This method minimized any manipulation or perturbation of the spectrum and was applied to a complex mixture of known compounds and to a plant extract, in both cases spiked with a compound (bisphenol A), which was subsequently removed by selective binding to a complementary MIP. What is described in this report is comparable with microextraction and may in due course be applied to a large number of analytical challenges. Copyright © 2014 John Wiley & Sons, Ltd.     

Tailoring a Dress to Single Protein Molecules: Proteins Can Do It Themselves through Localized Photo-Polymerization and Molecular Imprinting

Molecularly imprinted polymer nanoparticles (MIP NPs) are antibody-like recognition materials prepared by a template-assisted synthesis. MIP NPs able to target biomolecules, like proteins, are under the spotlight for their great potential in medicine, but efficiently imprinting biological templates is still very challenging. Here we propose generating a molecular imprint in single NPs, by photochemically initiating the polymerization from individual protein templates. In this way, each protein molecule tailors itself its own “polymeric dress”. For this, the template protein is covalently coupled with a photoinitiator, Eosin Y. Irradiated with light at 533 nm, the Eosin moiety acts as an antenna and transfers energy to a co-initiator (an amine), which generates a radical and initiates polymerization. As a result, a polymer network is forming only around the very template molecule, producing cross-linked NPs of 50 nm, with single binding sites showing high affinity (K_D 10⁻⁹ m ) for their biological target, and selectivity over other proteins.     

The preparation and adsorption properties of electrospun aramid nanofibers

The focus of this work is the preparation of aramid nanofibers via electrospinning technology and the study of their adsorption properties. In this article, aramid nanofibers were prepared by electrospinning aramid fibers solution with the addition of lithium chloride (LiCl). It showed a good adsorption capacity when methylene blue (MB) was used as the model target. There were much larger adsorption amounts and faster kinetics of uptaking target species of electrospun aramid nanofibers to MB than that of electrospun polyethersulfone (PES) nanofibers. Compared with activated carbon, aramid nanofibers also have a much faster adsorption rate to MB. Aramid nanofibers were subsequently used to effectively remove endocrine disruptors such as bisphenol A (BPA), phenol (Phe), and p‐hydroquinone (BPhe) from their aqueous solutions. Additionally, molecule imprinted technology enhances aramid nanofibers with much higher adsorption amounts and special adsorption property for endocrine disruptors. These results showed that aramid nanofibers have the potential to be used in environmental applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Preparation of 17β‐estradiol surface molecularly imprinted polymers and their application to the analysis of biological samples

17β‐Estradiol (E2) surface molecularly imprinted polymers have been prepared using functionalized monodispersed poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) beads as a support. The resulting polymers were found to be uniform in size (5 μm), and the surfaces of the microspheres possessed large pore‐like structures. A chromatographic experiment demonstrated that the resulting microspheres exhibited high levels of recognition and selectivity toward the target molecule. The particles were employed as a novel sorbent in a molecularly imprinted SPE protocol. A method was then developed involving the combination of the pretreatment with HPLC to determine the levels of estrogen secreted from Michigan Cancer Foundation‐7 cells. The obtained results revealed that the extraction recoveries of E2 from real samples were in the range of 73.0–97.5% with RSDs of < 7.5% (n = 3). Calibration curves were established with R values > 0.9996 for concentrations in the range of 0.50–100.00 ng/mL. The LOD of this new method was 0.14 ng/mL. Compared with traditional C₁₈ SPE agents, the particles showed high selectivity and extraction efficiency for E2 in the pretreatment process. The particles could therefore be used to determine trace estrogen in biological samples with a UV detector only.     

Preparation of Surface Molecularly Imprinted Poly(dopamine) Film for 4-Hydroxybenzoic Acid (4-BA) Recognition by One-Step Method

In this paper, we present a one-step aqueous self-polymerization strategy to prepare surface molecularly imprinted poly(dopamine) (PDA) film. The method is simple and convenient compared with the “template-guided” surface molecularly imprinted synthesis method and the layer-by-layer self-assembly and the surface-grafted molecularly imprinted synthesis methods. The molecularly imprinted PDA films could selectively bind the template molecules (4-Hydroxybenzoic acid as a model), and bisphenol A (BPA) imprinted PDA films were also investigated. Meanwhile, the 2-dimension imprinted film material was used very conveniently.