| 1. |
- Billing, Johan, et al.
(författare)
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Amphiphilic anthracene-amino acid conjugates as simple carbohydrate receptors in water
- 2002
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Ingår i: Supramolecular Chemistry. - : Informa UK Limited. - 1061-0278 .- 1029-0478. ; 14:4, s. 367-372
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Tidskriftsartikel (refereegranskat)abstract
- N-Alkylation of amino acid methyl esters with 9,10-bis-chloromethylanthracene, followed by methyl ester hydrolysis, yielded water-soluble amphiphilic amino acid-anthracene conjugates. In NMR-titration experiments, a L-arginine-anthracene conjugate was demonstrated to recognize p-nitrophenyl glycosides and sialylated oligosaccharides in D2O in a manner sensitive to the carbohydrate structure.
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| 2. |
- Billing, Johan, et al.
(författare)
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C2-Symmetric Macrocyclic Carbohydrate/Amino Acid Hybrids through Copper(I)-Catalyzed Formation of 1,2,3-Triazoles
- 2005
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 1520-6904 .- 0022-3263. ; 70:12, s. 4847-4850
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Tidskriftsartikel (refereegranskat)abstract
- An efficient method was developed for the preparation of macrocyclic carbohydrate/amino acid hybrids by macrocyclization with copper(I)-catalyzed 1,2,3-triazole formation. Methyl 2-amino-6-azido-3,4-di-O-benzoyl-2,6-dideoxy--D-glucopyranoside was prepared and coupled to two different N-propiolyl dipeptides (propiolyl-Tyr-Tyr-OH and propiolyl-Arg(Mtr)-Tyr-OH) to obtain bifunctional molecules carrying one azido group and one terminal alkyne. These bifunctional molecules were cyclodimerized using Cu(I)-catalyzed 1,3-dipolar cycloaddition of azides and alkynes to form macrocycles containing two 1,2,3-triazoles. Various cyclization methods were evaluated, and the most efficient conditions were found to be CuI and N,N-diisopropylethylamine in CH3CN.
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| 3. |
- Billing, Johan, et al.
(författare)
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Cyclic peptides containing a δ-sugar amino acid—synthesis and evaluation as artificial receptors
- 2005
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 61:4, s. 863-874
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Tidskriftsartikel (refereegranskat)abstract
- An Fmoc-protected δ-sugar amino acid, prepared by oxidation of a glucosamine derivative, was coupled to three different tripeptide tert-butyl esters (H-Tyr-Tyr-Tyr-OtBu, H-Tyr-Glu(OBzl)-Tyr-OtBu and H-Tyr-Arg(Mtr)-Tyr-OtBu) and the resulting sugar amino acid/amino acid hybrids were transformed into dimers that were subsequently cyclized to give three C2-symmetric macrocycles. The macrocycles were deprotected and their binding properties towards p-nitrophenyl glycosides, nucleotides, and purines were examined. Of the ligands screened, only some of the purines showed weak, but significant, binding.
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| 4. |
- Billing, Johan
(författare)
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Macrocyclic Carbohydrate/Amino Acid Hybrid Molecules - Synthesis and Evaluation as Artificial Receptors
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Methods were developed for the synthesis of three different types of macrocyclic carbohydrate/amino acid hybrid molecules. In the synthesis of the first type of macrocycles, a glucosamine derivative was oxidized at C6 and the obtained sugar amino acid was coupled to tripeptides. The resulting hybrids were transformed into dimers and cyclized in a macrolactamization step to obtain C2-symmetric macrocycles. In the second type of macrocycles, the same sugar amino acid was used together with tyrosine to prepare a C3-symmetric macrocycle with alternating sugar amino acid and tyrosine residues. In the synthesis of the third type of macrocycles, Cu(I)-catalysed 1,3-dipolar cycloaddition of azides and acetylenes was employed to form C2-symmetric carbohydrate/amino acid hybrid molecules containing two 1,2,3-triazole units. The macrocycles that were water-soluble were screened for affinity towards biomolecules. Weak, but significant, affinity was found for dAMP, dGMP, serotonin and caffeine for some of the macrocycles (Ka approx. 10 M-1) which indicates that molecules of this type have potential as artificial receptors. Possibilities to extend the developed methods to prepare further types of macrocycles are discussed.
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| 5. |
- Billing, Johan, et al.
(författare)
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Synthesis of a C3-symmetric macrocycle with alternating sugar amino acid and tyrosine residues
- 2005
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Ingår i: Tetrahedron Letters. - : Elsevier BV. - 0040-4039. ; 46:6, s. 991-993
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Tidskriftsartikel (refereegranskat)abstract
- A C3-symmetric macrocycle with alternating sugar amino acid and tyrosine residues was synthesized in seven steps from tyrosine tert-butyl ester and a sugar amino acid precursor derived from D-glucosamine. An Fmoc-protected D-glucosamine derivative was oxidized at C-6 to give the sugar amino acid, which was immediately coupled to tyrosine tert-butyl ester to produce an orthogonally protected building block. This building block was subsequently elongated to the trimer via the dimer, and finally cyclized to give the C3-symmetric macrocycle.
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| 6. |
- Chimuka, Luke, et al.
(författare)
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Selective extraction of triazine herbicides based on a combination of membrane assisted solvent extraction and molecularly imprinted solid phase extraction
- 2011
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673. ; 1218:5, s. 647-653
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Tidskriftsartikel (refereegranskat)abstract
- A selective extraction technique based on the combination of membrane assisted solvent extraction and molecularly imprinted solid phase extraction for triazine herbicides in food samples was developed. Simazine, atrazine, prometon, terbumeton, terbuthylazine and prometryn were extracted from aqueous food samples into a hydrophobic polypropylene membrane bag containing 1000 mu L of toluene as the acceptor phase along with 100 mg of MIP particles. In the acceptor phase, the compounds were re-extracted onto MIP particles. The extraction technique was optimised for the type of organic acceptor solvent, amount of molecularly imprinted polymers particles in the organic acceptor phase, extraction time and addition of salt. Toluene as the acceptor phase was found to give higher triazine binding onto MIP particles compared to hexane and cyclohexane. Extraction time of 120 min and 100 mg of MIP were found to be optimum parameters. Addition of salt increased the extraction efficiency for more polar triazines. The selectivity of the technique was demonstrated by extracting spiked cow pea and corn extracts where clean chromatograms were obtained compared to only membrane assisted solvent extraction or only molecularly imprinted solid phase extraction. The study revealed that this combination may be a simple way of selectively extracting compounds in complex samples. (C) 2010 Elsevier B.V. All rights reserved.
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| 7. |
- Dahl, Maria, et al.
(författare)
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Bone marrow transplantation without myeloablative conditioning in a mouse model for Diamond-Blackfan anemia corrects the disease phenotype
- 2021
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Ingår i: Experimental Hematology. - : Elsevier BV. - 0301-472X. ; 99, s. 2-53
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Tidskriftsartikel (refereegranskat)abstract
- Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplasia caused by a functional haploinsufficiency of genes coding for ribosomal proteins. Among these genes, the ribosomal protein S19 (RPS19) gene is the most frequently mutated. Previously, a mouse model deficient in RPS19 was developed by our laboratory, which recapitulates the hematopoietic disease phenotype by manifesting pathologic features and clinical symptoms of DBA. Characterization of this model revealed that chronic RPS19 deficiency leads to exhaustion of hematopoietic stem cells and subsequent bone marrow (BM) failure. In this study, we evaluated a nonmyeloablative conditioning protocol for BM transplants in RPS19-deficient mice by transplanting wild-type BM cells to RPS19-deficient recipients given no conditioning or sublethal doses of irradiation before transplant. We describe full correction of the hematopoietic phenotype in mice given sublethal doses of irradiation, as well as in animals completely devoid of any preceding irradiation. In comparison, wild-type animals receiving the same preconditioning regimen and number of transplanted cells exhibited significantly lower engraftment levels. Thus, robust engraftment and repopulation of transplanted cells can be achieved in reduced-intensity conditioned RPS19-deficient recipients. As gene therapy studies with autologous gene-corrected hematopoietic stem cells are emerging, we propose the results described here can guide determination of the level of conditioning for such a protocol in RPS19-deficient DBA. On the basis of our findings, a relatively mild conditioning strategy would plausibly be sufficient to achieve sufficient levels of engraftment and clinical success.
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| 8. |
- Duarte, Mariana, et al.
(författare)
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Solvent-free synthesis of chiral molecularly imprinted polymers: Porosity control using a nano-sized solid porogen
- 2016
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 133:41, s. 44104-44104
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Tidskriftsartikel (refereegranskat)abstract
- Molecularly imprinted polymers (MIPs) have been synthesized in the absence of a solvent using fumed silica nanoparticles to create a porous network. The method employed led to a chiral imprinting effect and allowed for an excellent control over the internal morphology of imprinted and non-imprinted polymer (NIP) materials. The polymers possess high surface areas (>300 m2) and identical pore size (112 Å). The MIP exhibited an imprinting factor (IF) of 9 and a selectivity value (α) of 1.83 for (−)-ephedrine.
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| 9. |
- Duarte, Mariana, et al.
(författare)
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Uniform Pores in Cross-Linked Polymers by Dispersed Fumed Silica Templating
- 2015
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 48:13, s. 4382-4387
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Tidskriftsartikel (refereegranskat)abstract
- Hydrophobic fumed silica dispersions in organic monomers were explored as a pore-forming system in polymer synthesis. The method developed provides a simple and effective way of controlling the pore size in highly cross-linked polymers. Fumed silica suspensions in divinylbenzene were polymerized with subsequent etching of the silica particles, therefore creating the porosity in the polymer. The resulting polymers are mesoporous materials, exhibiting an extremely narrow pore size distribution with an average pore size of about 100 angstrom, replicating the size of the nanofiller. BET surface areas were found appreciably high (similar to 350 m(2)/g). Furthermore, the rheological behavior of the prepolymerization mixtures was studied to elucidate the formation of the porous network and showed that a tridimensional network of particles is formed at a minimum silica fraction (Phi(v)) of 0.08.
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| 10. |
- Flodén, Jonas, 1974, et al.
(författare)
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Designing Intermodal Supply Chains
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- WP3 Report, Sustainable Intermodal Supply Systems for Biofuel and Bulk Freight
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