| 1. |
- Azenha, Manuel, et al.
(författare)
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Vapor-phase testing of the memory-effects in benzene- and toluene-imprinted polymers conditioned at elevated temperature
- 2013
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Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 802, s. 40-45
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Tidskriftsartikel (refereegranskat)abstract
- The preparation of polymers imprinted with common aromatic solvents such as benzene and toluene is an under-exploited subject of research. The present study was aimed at the understanding of whether true solvent memory effects can be achieved by molecular imprinting, as well as if they are stable at elevated temperature. A set of copolymers, comprising low and high cross-linking levels, was prepared from four different combinations of functional monomer and cross-linker, namely methacrylic acid (MAA)/ethylene glycol dimethacrylate (EGDMA), methyl methacrylate (MMA)/EGDMA, MAA/divinyl benzene (DVB) and MMA/DVB. Each possible combination was prepared separately in benzene, toluene and acetonitrile. The obtained materials were applied as coatings onto nickel-titanium (Ni-Ti) alloy wires which were incorporated into solid-phase microextraction devices and finally tested for their ability to competitively adsorb vapors from the headspace of an aqueous solution containing a few volatile organic compounds. Porosity analysis showed that, regardless of the solvent used, only a high cross-linking level permitted the preparation of mesoporous copolymers (BJH radius typically in the range 13-15nm), a requirement for providing accessibility to the targeted nanoscale-imprinted cavities. A noticeable exception was, however, observed for the MMA/DVB copolymers which exhibited much diminished BJH radius. The porosity data correlated well with the extraction profiles found, which suggested the presence of benzene-imprinted sites in all the highly cross-linked copolymers prepared in benzene, except for the MMA/DVB copolymers. Concerning the effect of an elevated conditioning temperature on the memory-effects created by the imprinting process, the results were clearly indicative that the tested copolymers, including the more robust highly cross-linked ones, are not suitable for high temperature applications such as solid-phase microextraction coupled to gas chromatography.
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| 2. |
- Berghaus, Melanie, et al.
(författare)
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Productive encounter : molecularly imprinted nanoparticles prepared using magnetic templates
- 2014
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Ingår i: Chemical Communications. - : Royal Society of Chemistry. - 1359-7345 .- 1364-548X. ; 50:64, s. 8993-8996
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis of core-shell nanoparticles by surface initiated reversible addition fragmentation chain transfer polymerization in presence of a chiral template conjugated to magnetic nanoparticles is reported. The approach leads to imprinted nanoparticles featuring enantioselectivity and enhanced affinity compared to nanoparticles prepared using free template.
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| 3. |
- Halhalli, Mahadeo, et al.
(författare)
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Cover and uncover : chiral switching exploiting templating and layer-by-layer grafting
- 2013
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Ingår i: Chemical Communications. - : Royal Society of Chemistry. - 1359-7345 .- 1364-548X. ; 49:64, s. 7111-7113
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Tidskriftsartikel (refereegranskat)abstract
- Consecutive grafting of crosslinked L-phenylalanine anilide, D-phenylalanine anilide and non-imprinted polymer layers on the surface of wide pore silica resulted in porous composite beads displaying enantiomeric discrimination reflecting the last grafted layer. This no longer holds for beads freed from silica, which instead display enantio-selectivity reflecting the first grafted layer.
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| 4. |
- Kadhirvel, Porkodi, et al.
(författare)
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Chromatographycally efficient microspherical composites of molecularly imprinted xerogels deposited inside mesoporous silica
- 2014
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1355, s. 158-163
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Tidskriftsartikel (refereegranskat)abstract
- A different approach to the preparation of microspheric particles of molecularly imprinted xerogels (MIX) is presented here. The technique consisted of filling up the pores of spherical, mesoporous, bare silica particles with a pregelification mixture by applying pressure. Upon gelification and drying, thin layers of MIX were deposited on the mesopores. Spherical composites of S-naproxen (S-NAP) imprints were produced by following this simple strategy. The performance of the imprints was quite satisfactory in terms of recognition ability (ascertained by selectivity against ibuprofen, α=4.9, and an imprinting factor of 13) whereas an outstanding improvement on dynamic features (expressed as column efficiency), as compared to the corresponding bulk format MIX (9 vs. 1.2 theoretical plates/cm), was reached
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| 5. |
- Kadhirvel, Porkodi, et al.
(författare)
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Imidazolium-based functional monomers for the imprinting of the anti-inflammatory drug naproxen : Comparison of acrylic and sol–gel approaches
- 2013
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1314, s. 115-123
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Tidskriftsartikel (refereegranskat)abstract
- Imidazolium-based monomers were, for the first time, employed in a comprehensive investigation of the molecular imprinting process of naproxen in both acrylic and sol-gel tridimensional networks. To this end, molecularly imprinted polymer (MIP) and xerogel (MIX) were both optimized for performance, by testing different porogen, template speciation and component ratios. The developed imprints were characterized for their pore properties (nitrogen adsorption analysis), site heterogeneity, binding properties and other performance parameters such as the imprinting factor, selectivity (HPLC column tests), column efficiency and mass transfer kinetics (frontal analysis study). MIP exhibited mesoporosity (Dp 29nm), whereas MIX did not, which was reflected in both the lower number of accessible imprinted sites (4.9μmol/g versus 3.7μmol/g) and the slower binding/dissociation in MIX. The naproxen/ibuprofen selectivity ratio was estimated as 6.2 for the MIX and 2.5 for the MIP. Given the high importance of capacity and fast mass transfer in typical applications of imprinted materials, and the satisfactory selectivity of MIP, it can be concluded that the acrylic approach was globally the most advantageous. Still, the remarkably high selectivity of MIX and its reasonable capacity demonstrate that future work devoted to further optimization of both formats is worthwhile.
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| 6. |
- Kadhirvel, Porkodi, et al.
(författare)
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Recognitive nano-thin-film composite beads for the enantiomeric resolution of the metastatic breast cancer drug aminoglutethimide
- 2014
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1358, s. 93-101
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Tidskriftsartikel (refereegranskat)abstract
- Straightforward crushing and sieving bulk polymeric R-aminoglutethimide-imprinted materials were prepared by classical free radical polymerization, whereas nano thin walled grafted imprinted materials were prepared using RAFT mediated control polymerization technique. A stoichiometric non-covalent approach based on a triply hydrogen bonding functional monomer-template 1:1 complex (K=599mol(-1)L(-1)) led to chiral selectors far outperforming previously used selectors for resolving this racemate. The recognitive materials produced here (enantioselectivity factors, α∼10) also have no match within the previously reported enantioselective imprinted polymers (α 1.2-4.5). We here demonstrate a potentially generic solution to produce good quality grafted MIPs for templates interacting by hydrogen bonding alone, relying on solvent polarity tuning, significantly extending the range of templates compatible with this format.
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| 7. |
- Kecili, Rüstem, et al.
(författare)
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Fast identification of selective resins for removal of genotoxic aminopyridine impurities via screening of molecularly imprinted polymer libraries
- 2014
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1339, s. 65-72
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Tidskriftsartikel (refereegranskat)abstract
- This study describes the identification and evaluation of molecularly imprinted polymers (MIPs) for the selective removal of potentially genotoxic aminopyridine impurities from pharmaceuticals. Screening experiments were performed using existing MIP resin libraries to identify resins selective towards those impurities in the presence of model pharmaceutical compounds. A hit resin with a considerable imprinting effect was found in the screening and upon further investigation, the resin was found to show a broad selectivity towards five different aminopyridines in the presence of the two model active pharmaceutical ingredients (APIs) piroxicam and tenoxicam.
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| 8. |
- Narayanaswamy, Pradeep, et al.
(författare)
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Lipidomic “Deep Profiling” : An Enhanced Workflow to Reveal New Molecular Species of Signaling Lipids
- 2014
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 86:6, s. 3043-3047
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Tidskriftsartikel (refereegranskat)abstract
- Current mass spectrometry-based lipidomics aims to comprehensively cover wide ranges of lipid classes. We introduce a strategy to capture phospho-monoester lipids and improve the detection of long-chain base phosphates (LCB-Ps, e.g., sphingosine-1-phosphate). Ten novel LCB-Ps (d18:2, t20:1, odd carbon forms) were discovered and characterized in tissues from human and mouse, as well in D. melanogaster and S. cerevisiae. These findings have immediate relevance for our understanding of sphingosine-1-phosphate biosynthesis, signaling, and degradation.
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| 9. |
- Nematollahzadeh, Ali, et al.
(författare)
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Robust and selective nano cavities for protein separation : An interpenetrating polymer network modified hierarchically protein imprinted hydrogel
- 2014
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1345, s. 154-163
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, we report a novel method for the reinforcement of hierarchically structured molecularly imprinted polymer (MIP) for the separation of human serum albumin (HSA) and immunoglobulin G (IgG) proteins under pressure driven flow conditions. The template proteins (HSA or IgG) were first physically adsorbed at their isoelectric point on the surface of wide pore silica particles. Thereafter, the pore system was filled with a monomer solution and polymerized to form a lightly crosslinked polyacrylamide network covering the protein template. In order to enhance the rigidity of the hydrogels, different type of crosslinkers such as ethylene glycol dimethacrylate (EGDMA), 3,4-dihydroxyphenethylamine (DA) and methylene-bis-acrylamide (MBA), at least partially interpenetrated into the initially made acrylamide base hydrogel leading to formation of an interpenetrating polymer network (IPN). Then the silica matrix was removed to leave highly porous and reinforced MIP. TGA together with FT-IR and TEM analysis supported the interpenetration of the secondary crosslinkers in the initially formed polymer matrix. The compression property of the modified hydrogels as a function of degree of swelling was in the following order: DA>EGDMA>MBA-IPN-modified hydrogel. Batch binding assay verified the capability of the IPN modified MIPs to capture the target proteins. Moreover, solid phase extraction, HPLC and SDS-PAGE revealed that the EGDMA modified MIP could selectively capture and separate the proteins from human serum or fermentation broth
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| 10. |
- Olsson, Gustaf D., et al.
(författare)
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Theoretical studies of 17-beta-estradiol-imprinted prepolymerization mixtures : insights concerning the roles of cross-linking and functional monomers in template complexation and polymerization
- 2013
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 52:39, s. 13965-13970
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Tidskriftsartikel (refereegranskat)abstract
- In this study, computational methods were employed in efforts to elucidate physical mechanisms underlying the ligand selectivity of polymeric sorbents produced through the molecular imprinting of 17-beta-estradiol. Previous computational and experimental studies had identified candidate systems applicable to the development of synthetic polymeric receptors for the detection and possible removal of pollutants with endocrine-disrupting properties. Here we present a series of comprehensive molecular dynamics studies of candidate molecular imprinting prepolymerization systems. The results from the studies highlight the role of the cross-linker and the importance of the interplay between functionalities of the various monomers employed in template complexation. The significance of these results for future studies is discussed.
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