| 1. |
- Ye, Lei
(author)
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Artificial receptors: New opportunities for the exploitation of molecularly imprinted polymers
- 1999
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Doctoral thesis (other academic/artistic)abstract
- Molecular imprinting, method for creating artificial receptors that are mimics of biological antibodies and receptors, is based on the concept of creating substrate-specific recognition sites in polymeric matrices by means of template polymerisation. The polymeric receptors produced display favourable binding characteristics, such as high affinity and specificity towards the substrate molecules. Compared to natural antibodies and receptors, imprinted polymers are much more stable and can therefore be utilised under considerably harsher conditions. In the researches described in this thesis, non-covalent interactions are the major force driving the assembly of imprinted receptors. Given that non-covalent molecular interactions dominate in all biological recognition processes, their application in molecular imprinting is in principle unlimited. The general applicability of the non-covalent approach for the imprinting of various substrate molecules is reflected in the increasing number of publications in recent years. Non-covalent molecularly imprinted polymers have been applied in many areas, for example as stationary phases in chiral separation, as affinity adsorbents for sample pre-treatment using solid-phase extraction, as antibody mimics for drug determination, etc. Summarised in this thesis are novel applications for molecularly imprinted polymers prepared via the non-covalent approach. Artificial antibodies against corticosteroids have been prepared that exhibit binding behaviour similar to their natural counterparts. The utility of imprinted polymers for the screening of combinatorial chemical libraries is demonstrated, where the compounds of interest can be specifically isolated from libraries composed of many similar structures. As specific adsorbents, molecularly imprinted polymers are used for product purification following chemical synthesis and for in situ product removal during a biotransformation process to enhance product yield. Finally, a new imprinting methodology is developed for the production of affinity microspheres that have various applications in analytical and medical sciences.
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| 2. |
- Chaudhary, Shilpi, et al.
(author)
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Controlled short-linkage assembly of functional nano-objects
- 2014
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In: Applied Surface Science. - : Elsevier BV. - 1873-5584 .- 0169-4332. ; 300, s. 22-28
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Journal article (peer-reviewed)abstract
- In this work, we report a method that allows the deterministic, photo-controlled covalent assembly of nanoparticles directly on surface. As a model system, we study the conjugation of molecularly imprinted polymer (MIP) nanoparticles on a glass surface and confirm that the immobilized nanoparticles maintain their molecular recognition functionality. The glass slide was first modified with perfluorophenylazide and then used to bind MIP nanoparticles under UV irradiation. After each step the surface was analyzed by water contact angle measurement, fluorescence microscopy, scanning electron microscopy, and/or synchrotron-based X-ray photoelectron spectroscopy. The MIP nanoparticles immobilized on the glass surface remained stable and maintained specific binding for the template molecule, propranolol. The method developed in this work allows MIP nanoparticles to be directly coupled to a flat surface, offering a straightforward means to construct robust chemical sensors. Using the reported photo conjugation method, it is possible to generate patterned assembly of nanoparticles using a photomask. Since perfluorophenylazide-based photochemistry works with all kinds of organic material, the method developed in this work is expected to enable immobilization of not only MIPs but also other kinds of organic and inorganic-organic core-shell particles for various applications involving photon or electron transfer. (C) 2014 The Authors. Published by Elsevier B.V. All rights reserved.
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| 3. |
- Kamra, Tripta, et al.
(author)
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Covalent immobilization of molecularly imprinted polymer nanoparticles using an epoxy silane.
- 2015
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In: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 445, s. 277-284
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Journal article (peer-reviewed)abstract
- Molecularly imprinted polymers (MIPs) can be used as antibody mimics to develop robust chemical sensors. One challenging problem in using MIPs for sensor development is the lack of reliable conjugation chemistry that allows MIPs to be fixed on transducer surface. In this work, we study the use of epoxy silane to immobilize MIP nanoparticles on model transducer surfaces without impairing the function of the immobilized nanoparticles. The MIP nanoparticles with a core-shell structure have selective molecular binding sites in the core and multiple amino groups in the shell. The model transducer surface is functionalized with a self-assembled monolayer of epoxy silane, which reacts with the core-shell MIP particles to enable straightforward immobilization. The whole process is characterized by studying the treated surfaces after each preparation step using atomic force microscopy, scanning electron microscopy, fluorescence microscopy, contact angle measurements and X-ray photoelectron spectroscopy. The microscopy results show that the MIP particles are immobilized uniformly on surface. The photoelectron spectroscopy results further confirm the action of each functionalization step. The molecular selectivity of the MIP-functionalized surface is verified by radioligand binding analysis. The particle immobilization approach described here has a general applicability for constructing selective chemical sensors in different formats.
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| 4. |
- Xu, Zhifeng, et al.
(author)
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Fluorescent Boronic Acid Polymer Grafted on Silica Particles for Affinity Separation of Saccharides.
- 2014
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In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 6:3, s. 1406-1414
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Journal article (peer-reviewed)abstract
- Boronic acid affinity gels are important for effective separation of biological active cis-diols, and are finding applications both in biotech industry and in biomedical research areas. To increase the efficacy of boronate affinity separation, it is interesting to introduce repeating boronic acid units in flexible polymer chains attached on solid materials. In this work, we synthesize polymer brushes containing boronic acid repeating units on silica gels using surface-initiated atom transfer radical polymerization (ATRP). A fluorescent boronic acid monomer is first prepared from an azide-tagged fluorogenic boronic acid and an alkyne-containing acrylate by Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction (the CuAAC click chemistry). The boronic acid monomer is then grafted to the surface of silica gel modified with an ATRP initiator. The obtained composite material contains boronic acid polymer brushes on surface and shows favorable saccharide binding capability under physiological pH conditions, and displays interesting fluorescence intensity change upon binding fructose and glucose. In addition to saccharide binding, the flexible polymer brushes on silica also enable fast separation of a model glycoprotein based on selective boronate affinity interaction. The synthetic approach and the composite functional material developed in this work should open new opportunities for high efficiency detection, separation, and analysis of not only simple saccharides, but also glycopeptides and large glycoproteins.
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| 5. |
- Zhou, Tongchang, et al.
(author)
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Molecularly Imprinted Polymer Beads Prepared by Pickering Emulsion Polymerization for Steroid Recognition
- 2014
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In: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 131:1, s. 39606-39606
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Journal article (peer-reviewed)abstract
- Pickering emulsion polymerization was used to synthesize molecularly imprinted polymer beads for the selective recognition of 17-beta-estradiol under aqueous conditions. Scanning electron microscopy analysis indicated that the imprinted polymer beads had a small diameter with a narrow size distribution (18.9 +/- 2.3 mu m). The reduction in particle size achieved in this study was attributed to the altered polarity of the stabilizing nanoparticles used in the Pickering emulsion. The imprinted polymer beads could be used directly in water and showed a high binding affinity for the template molecule, 17-beta-estradiol, and its structural analogs. These water-compatible polymer beads could be used as affinity adsorbents for the extraction and analysis of low-abundance steroid compounds in aqueous samples. (C) 2013 Wiley Periodicals, Inc.
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| 6. |
- Zhou, Tongchang, et al.
(author)
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Preparation of protein imprinted polymer beads by Pickering emulsion polymerization
- 2015
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In: Journal of Materials Chemistry. B. - : Royal Society of Chemistry (RSC). - 2050-7518 .- 2050-750X. ; 3:7, s. 1254-1260
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Journal article (peer-reviewed)abstract
- We present a new method for preparation of protein-specific polymer beads based on surface molecular imprinting in Pickering emulsion. In the first step, adult human hemoglobin (Hb) was adsorbed on silica nanoparticles. The protein-coated silica particles were then used to stabilize an oil-in-water emulsion (Pickering emulsion) composed of cross-linking monomer in the oil phase. After free radical polymerization of the oil phase, the protein-silica particles were removed to leave Hb-imprinted sites on the polymer surface. The protein-imprinted polymer microspheres were characterized by scanning electron microscopy and their selectivity was investigated by protein binding analysis. The new synthetic method based on Pickering emulsion polymerization produced easily accessible Hb binding sites on the surface of spherical polymer particles, which are useful for protein separation, purification and analysis.
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| 7. |
- Hajizadeh, Solmaz, et al.
(author)
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Cryogelation of molecularly imprinted nanoparticles: A macroporous structure as affinity chromatography column for removal of β-blockers from complex samples.
- 2013
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In: Journal of chromatography. A. - : Elsevier BV. - 1873-3778 .- 0021-9673. ; 1274, s. 6-12
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Journal article (peer-reviewed)abstract
- In this work, a new macroporous molecularly imprinted cryogel (MIP composite cryogel) was synthesized by glutaraldehyde cross-linking reaction of poly(vinyl alcohol) (PVA) particles and amino-modified molecularly imprinted core-shell nanoparticles. The MIP core-shell nanoparticles were prepared using propranolol as a template by one-pot precipitation polymerization with sequential monomer addition. The characteristics of the MIP composite cryogel were studied by scanning electron microscopy (SEM) and texture analyzer. The macroporous structure of the composite (with the pore size varying from a few micrometers to 100μm) enabled high mass transfer of particulate-containing fluids. In a solid phase extraction (SPE) process, the efficiency and selectivity of the MIP composite cryogel were investigated, where the cryogel was used as an affinity matrix to remove propranolol from aqueous solution as well as from complex plasma sample without prior protein precipitation. The MIP composite cryogel maintained high selectivity and stability and could be used repeatedly after regeneration.
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| 8. |
- Liu, Chen, et al.
(author)
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Separation and Recycling of Functional Nanoparticles Using Reversible Boronate Ester and Boroxine Bonds
- 2019
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In: Industrial and Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 58:11, s. 4695-4703
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Journal article (peer-reviewed)abstract
- The sustainable and green chemistry concept calls for effective separation and recycling of valuable functional nanoparticles. In this work, a viable approach to separate and recover synthetic nanoparticles without involving heavy-duty instruments was established. The nanoparticle separation was enabled by using reversible boronate ester and boroxine bonds formed between boronic acid-functionalized nanoparticles and poly(vinyl alcohol) and between the nanoparticles themselves. The reversible covalent bonds were controlled by simple adjustment of solvent pH. To demonstrate the viability of the approach, two types of nanoparticles - inorganic silica nanoparticles and organic molecularly imprinted nanoparticles functionalized with boronic acid on their surface - were used as models. Upon addition of poly(vinyl alcohol) and adjustment to basic pH, the nanoparticles formed aggregates and readily settled from solution. After changing to an acidic solvent, the boronate ester bonds formed between boronic acid-functionalized nanoparticles and poly(vinyl alcohol) were hydrolyzed, and poly(vinyl alcohol) was released from the nanoparticle aggregates. The particles remained as aggregates due to the formation of new, interparticle boroxine bonds. By use of pH-controlled dynamic particle aggregation, propranolol-imprinted nanoparticles could be easily recovered and used repetitively without centrifugation. This work provides a new approach for recovery of valuable functional nanomaterials for potentially large-scale industrial applications. ©
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| 9. |
- Ara, Behisht, et al.
(author)
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Preparation and characterization of uniform molecularly imprinted polymer beads for separation of triazine herbicides
- 2012
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In: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 126:1, s. 315-321
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Journal article (peer-reviewed)abstract
- Uniform molecularly imprinted polymer beads were synthesized by precipitation polymerization for separation of triazine herbicides. A series of imprinted polymers were prepared using ametryn as template and divinylbenzene as crosslinking monomer, in combination with three different functional monomers under different solvent conditions. Under optimized reaction conditions, we obtained uniform molecularly imprinted polymer microspheres that display favorable molecular binding selectivity for triazine herbicides. The imprinted polymer beads synthesized using methacrylic acid as functional monomer in a mixture of methyl ethyl ketone and heptane showed the best results in terms of particle size distribution and molecular selectivity. Compared with nonimprinted polymer microspheres, the imprinted microspheres displayed significantly higher binding for a group of triazine herbicides including atrazine, simazine, propazine, ametryn, prometryn, and terbutryn. For the first time, precipitation polymerization has been used to produce highly uniform imprinted microspheres suitable for affinity separation of triazine herbicides. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
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| 10. |
- Bagan Navarro, Hector, et al.
(author)
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Thermoresponsive Polymer Brushes on Organic Microspheres for Biomolecular Separation and Immobilization
- 2017
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In: Macromolecular Chemistry and Physics. - : Wiley. - 1022-1352. ; 218:3
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Journal article (peer-reviewed)abstract
- A new method is developed to synthesize organic microsphere-supported polymer brushes for affinity separation of saccharides and glycoproteins. In the first step, crosslinked polymer microspheres are synthesized using atom transfer radical polymerization (ATRP). The terminal ATRP initiators on the microspheres are used to graft polymer brushes from propargyl acrylate and N-isopropyl acrylamide. The microsphere-supported polymer brushes are conjugated with an azide-tagged phenylboronic acid to complete the material synthesis. The microsphere-supported, boronic acid-containing polymer brushes are able to bind not only low molecular weight cis-diol compounds but also glycoproteins. The synthetic procedure developed in this work provides a convenient means for preparing all-organic microsphere-supported polymer brushes that have high alkaline stability. Using the surface-attached polymer brushes to immobilize a catalytic glycoprotein (horseradish peroxidase), it is possible to retain on-particle enzyme activity due to the open structure of the polymer brushes and the oriented immobilization. (Figure presented.).
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