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Irgum, Knut
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Publications (10 of 72) Show all publications
Dinh, V. M., Khokarale, S. G., Ojeda-May, P., Sparrman, T., Irgum, K. & Mikkola, J.-P. (2024). Ionic liquid strategy for chitosan production from chitin and molecular insights. RSC Sustainability
Open this publication in new window or tab >>Ionic liquid strategy for chitosan production from chitin and molecular insights
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2024 (English)In: RSC Sustainability, E-ISSN 2753-8125Article in journal (Refereed) Epub ahead of print
Abstract [en]

To produce chitosan is an interesting research. Chitosan is an important polysaccharide in terms of its various applications in industries and is produced from chitin, an abundant biopolymer in crustacean shell biomass wastes. Traditional processes for chitosan manufacture are commonly based on highly concentrated alkaline or acid solutions which are, however, severely eroding and harmful to the environment. In this study, we have described a ‘greener’ method using 1-ethyl-3-methylimidazolium acetate, [Emim][OAc] ionic liquid (IL), for decrystallization of shrimp crystalline chitin flakes followed by a microwave-mediated NaOH or tetrabutylammonium hydroxide, [TBA][OH], solution-based deacetylation for chitosan production. The decrease in crystallinity in IL pre-treated chitin was confirmed by XRD and SEM analysis which subsequently benefited chitosan production with up to 85% degree of deacetylation (%DDA) in shorter time periods (1-2 hours) and lower alkaline concentrations (20-40%). The %DDA in chitin/chitosan was estimated via FT-IR and NMR analysis. Notably, we could regenerate the ionic liquids: in case of [Emim][OAc] 97 wt.% and in case of [TBA][OH] 83 wt.% could be reused. Roles of ionic liquids in the process were discussed. Molecular dynamics (MD) simulations showed the roles of [TBA]+ cations in the molecular driving forces of [TBA][OH]-induced deacetylation mechanism. The strategy promises a sustainable and milder reaction approach to the existing highly corrosive alkaline- or acid-involved processes for chitosan production.

National Category
Chemical Sciences
Research subject
sustainability
Identifiers
urn:nbn:se:umu:diva-222314 (URN)10.1039/d4su00053f (DOI)
Available from: 2024-03-13 Created: 2024-03-13 Last updated: 2024-03-13
Huynh, C. M., Mavliutova, L., Sparrman, T., Sellergren, B. & Irgum, K. (2023). Elucidation of the binding orientation in α2,3- and α2,6-linked neu5ac-gal epitopes toward a hydrophilic molecularly imprinted monolith. ACS Omega, 8(46), 44238-44249
Open this publication in new window or tab >>Elucidation of the binding orientation in α2,3- and α2,6-linked neu5ac-gal epitopes toward a hydrophilic molecularly imprinted monolith
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2023 (English)In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 46, p. 44238-44249Article in journal (Refereed) Published
Abstract [en]

N-Acetylneuraminic acid and its α2,3/α2,6-glycosidic linkages with galactose (Neu5Ac-Gal) are major carbohydrate antigen epitopes expressed in various pathological processes, such as cancer, influenza, and SARS-CoV-2. We here report a strategy for the synthesis and binding investigation of molecularly imprinted polymers (MIPs) toward α2,3 and α2,6 conformations of Neu5Ac-Gal antigens. Hydrophilic imprinted monoliths were synthesized from melamine monomer in the presence of four different templates, namely, N-acetylneuraminic acid (Neu5Ac), N-acetylneuraminic acid methyl ester (Neu5Ac-M), 3′-sialyllactose (3SL), and 6′-sialyllactose (6SL), in a tertiary solvent mixture at temperatures varying from −20 to +80 °C. The MIPs prepared at cryotemperatures showed a preferential affinity for the α2,6 linkage sequence of 6SL, with an imprinting factor of 2.21, whereas the α2,3 linkage sequence of 3SL resulted in nonspecific binding to the polymer scaffold. The preferable affinity for the α2,6 conformation of Neu5Ac-Gal was evident also when challenged by a mixture of other mono- and disaccharides in an aqueous test mixture. The use of saturation transfer difference nuclear magnetic resonance (STD-NMR) on suspensions of crushed monoliths allowed for directional interactions between the α2,3/α2,6 linkage sequences on their corresponding MIPs to be revealed. The Neu5Ac epitope, containing acetyl and polyalcohol moieties, was the major contributor to the sequence recognition for Neu5Ac(α2,6)Gal(β1,4)Glc, whereas contributions from the Gal and Glc segments were substantially lower.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-217983 (URN)10.1021/acsomega.3c06836 (DOI)38027366 (PubMedID)2-s2.0-85178321169 (Scopus ID)
Funder
EU, Horizon 2020, H2020EU, Horizon 2020, 722171
Available from: 2023-12-14 Created: 2023-12-14 Last updated: 2023-12-15Bibliographically approved
Jablonski, P., Dinh, N. P., Lascu, I., Tănase, A.-M., Christensen, M., Khokarale, S. G., . . . Irgum, K. (2023). Scalable and sustainable processing of intracellular polyhydroxyalkanoates with biobased solvents. ACS Sustainable Chemistry and Engineering, 11(51), 17990-18000
Open this publication in new window or tab >>Scalable and sustainable processing of intracellular polyhydroxyalkanoates with biobased solvents
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2023 (English)In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 11, no 51, p. 17990-18000Article in journal (Refereed) Published
Abstract [en]

The replacement of fossil-based plastics with biobased and biodegradable alternatives has become an important research challenge in recent years, aiming to eliminate the negative environmental impact of persistent plastics in nature. In this report, design of experiments was successfully exploited to develop an efficient and sustainable method for extracting intracellular PHA from Photobacterium ganghwense C2.2 using dihydrolevoglucosenone (Cyrene) and ethanol as biobased solvents obtainable from sustainable sources. The extraction conditions were studied and optimized against the yield and molecular weight. The temperature range for the extraction was scouted by using differential scanning calorimetry, while size exclusion chromatography coupled to refractive index and multiangle light scattering detectors was used to assess the molecular weights of the extracted polymers. The examined ranges in the model were, respectively, 1.6–8.4% (w/v) of lyophilized cells content per 10 mL of solvent, 3–17 min extraction time, and temperatures from 116 to 144 °C. Time and temperature strongly affected the extraction yields and molecular weights of the obtained polymers while the concentration of bacterial biomass only effected the molecular weight. Several quadratic and interaction coefficients were significant in the well-fit partial least-squares regression models (R2 > 0.8, Q2 > 0.6) indicating that nonlinear effects and interacting parameter contributed to the optimization targets. The optimized extraction should be performed at 130 °C for 15 min with 2% loading of bacterial biomass. The predicted yield and molecular weight of the polymer matched the values obtained from the real experiment under the optimized conditions. The method setup provided similar yield and higher molecular weight in much shorter time compared to overnight Soxhlet extraction with CHCl3. The clean 1H nuclear magnetic resonance spectra of polymers extracted from bacteria indicate that high purity materials can be obtained using an optimized extraction scheme. Additionally, the Cyrene solvent could be recycled at least five times and still performed the extraction equally well as the fresh solvent. Finally, the current method demonstrated a high potential for scalability using a HP4750 stirred filtration cell. Three different filtration conditions were tested, achieving up to 97.4% recovery at 80 °C using a 0.3 μm glass fiber membrane, with a flux of 312.5 LMH.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-218282 (URN)10.1021/acssuschemeng.3c05422 (DOI)001131587500001 ()2-s2.0-85181148255 (Scopus ID)
Funder
Mistra - The Swedish Foundation for Strategic Environmental Research, 2016-02011Bio4Energy
Available from: 2023-12-19 Created: 2023-12-19 Last updated: 2024-01-15Bibliographically approved
Huynh, C. M., Arribas Díez, I., Thi, H. K., Jensen, O. N., Sellergren, B. & Irgum, K. (2023). Terminally phosphorylated triblock polyethers acting both as templates and pore-forming agents for surface molecular imprinting of monoliths targeting phosphopeptides. ACS Omega, 8(9), 8791-8803
Open this publication in new window or tab >>Terminally phosphorylated triblock polyethers acting both as templates and pore-forming agents for surface molecular imprinting of monoliths targeting phosphopeptides
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2023 (English)In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 9, p. 8791-8803Article in journal (Refereed) Published
Abstract [en]

The novel process reported here described the manufacture of monolithic molecularly imprinted polymers (MIPs) using a terminally functionalized block copolymer as the imprinting template and pore-forming agent. The MIPs were prepared through a step-growth polymerization process using a melamine-formaldehyde precondensate in a biphasic solvent system. Despite having a relatively low imprinting factor, the use of MIP monolith in liquid chromatography demonstrated the ability to selectively target desired analytes. An MIP capillary column was able to separate monophosphorylated peptides from a tryptic digest of bovine serum albumin. Multivariate data analysis and modeling of the phosphorylated and nonphosphorylated peptide retention times revealed that the number of phosphorylations was the strongest retention contributor for peptide retention on the monolithic MIP capillary column.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-205479 (URN)10.1021/acsomega.3c00007 (DOI)000946549200001 ()36910939 (PubMedID)2-s2.0-85148899091 (Scopus ID)
Funder
EU, Horizon 2020, 722171
Available from: 2023-03-16 Created: 2023-03-16 Last updated: 2023-11-23Bibliographically approved
Khokarale, S. G., Jablonski, P., Nikjoo, D., Dinh, V. M., Sundman, O., Irgum, K. & Mikkola, J.-P. (2022). Poly (vinylidene difluoride) polymer in 1-ethyl-3-methylimidazolium acetate and acetic acid containing solvents: Tunable and recoverable solvent media to induce crystalline phase transition and porosity. Sustainable Chemistry, 3(4), 455-474
Open this publication in new window or tab >>Poly (vinylidene difluoride) polymer in 1-ethyl-3-methylimidazolium acetate and acetic acid containing solvents: Tunable and recoverable solvent media to induce crystalline phase transition and porosity
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2022 (English)In: Sustainable Chemistry, ISSN 2673-4079, Vol. 3, no 4, p. 455-474Article in journal (Refereed) Published
Abstract [en]

In this report, 1-ethyl-3-methylimidazolium acetate, [EMIM][AcO] ionic liquid (IL) and acetic acid (AA) comprised solvents were used for the thermal treatment of poly (vinylidene difluoride), PVDF. Here, besides the various combinations of IL and AA in solvents, the pure IL and AA were also applied as a solvent upon thermal treatments. The samples obtained after the treatment were analysed for structural and crystalline phase changes, porosity, and molecular weight distribution with various analytical techniques. The Kamlet-Taft parameters measurement of the IL and AA containing solvents with different solvatochromic dyes was also performed to examine their solvent properties and correlate with the properties of the treated PVDF materials. The treatment of PVDF with pure IL results in the formation of highly carbonaceous material due to extensive dehydroflurination (DHF) as well as possibly successive cross-linking in the polymer chains. Upon IL and AA combined solvent treatment, the neat PVDF which composed of both α- and β crystalline phases was transformed to porous and β-phase rich material whereas in case of pure AA the non-porous and pure α-phase polymeric entity was obtained. A combined mixture of IL and AA resulted in a limited the DHF process and subsequent cross-linking in the polymer chains of PVDF allowed the formation of a porous material. It was observed that the porosity of the thermally treated materials was steadily decreasing with increase in the amount of AA in solvents composition and solvent with an AA:IL mole ratio of 2:1 resulted in a PVDF material with the highest porosity amongst the applied solvents. A recovery method for the IL and AA combined solvent after the thermal treatment of PVDF was also established. Hence, with varying the type of solvents in terms of composition, the highly carbonaceous materials as well as materials with different porosities as well as crystalline phases can be obtained. Most importantly here, we introduced new IL and AA containing recoverable solvents for the synthesis of porous PVDF material with the electroactive β-phase.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
poly (vinylidene difluoride), ionic liquid, acetic acid, crystalline phase transition, porosity, recoverable solvents
National Category
Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-200717 (URN)10.3390/suschem3040028 (DOI)
Funder
Bio4EnergyKnut and Alice Wallenberg Foundation
Available from: 2022-11-02 Created: 2022-11-02 Last updated: 2022-11-02Bibliographically approved
Lascu, I., Tănase, A. M., Jablonski, P., Chiciudean, I., Preda, M. I., Avramescu, S., . . . Stoica, I. (2022). Revealing the phenotypic and genomic background for pha production from rapeseed-biodiesel crude glycerol using photobacterium ganghwense C2.2. International Journal of Molecular Sciences, 23(22), Article ID 13754.
Open this publication in new window or tab >>Revealing the phenotypic and genomic background for pha production from rapeseed-biodiesel crude glycerol using photobacterium ganghwense C2.2
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2022 (English)In: International Journal of Molecular Sciences, ISSN 1661-6596, E-ISSN 1422-0067, Vol. 23, no 22, article id 13754Article in journal (Refereed) Published
Abstract [en]

Polyhydroxyalkanoates (PHA) are promising biodegradable and biocompatible bioplastics, and extensive knowledge of the employed bacterial strain’s metabolic capabilities is necessary in choosing economically feasible production conditions. This study aimed to create an in-depth view of the utilization of Photobacterium ganghwense C2.2 for PHA production by linking a wide array of characterization methods: metabolic pathway annotation from the strain’s complete genome, high-throughput phenotypic tests, and biomass analyses through plate-based assays and flask and bioreactor cultivations. We confirmed, in PHA production conditions, urea catabolization, fatty acid degradation and synthesis, and high pH variation and osmotic stress tolerance. With urea as a nitrogen source, pure and rapeseed-biodiesel crude glycerol were analyzed comparatively as carbon sources for fermentation at 20 °C. Flask cultivations yielded 2.2 g/L and 2 g/L PHA at 120 h, respectively, with molecular weights of 428,629 g/mol and 81,515 g/mol. Bioreactor batch cultivation doubled biomass accumulation (10 g/L and 13.2 g/L) in 48 h, with a PHA productivity of 0.133 g/(L·h) and 0.05 g/(L·h). Thus, phenotypic and genomic analyses determined the successful use of Photobacterium ganghwense C2.2 for PHA production using urea and crude glycerol and 20 g/L NaCl, without pH adjustment, providing the basis for a viable fermentation process.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
Biolog Phenotypic Microarray, biopolymer molecular mass, bioreactor, crude glycerol, fatty acid metabolism, genomics, polyhydroxyalkanoates
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-201464 (URN)10.3390/ijms232213754 (DOI)000887480800001 ()2-s2.0-85142628112 (Scopus ID)
Available from: 2022-12-06 Created: 2022-12-06 Last updated: 2023-09-05Bibliographically approved
Jablonski, P., Nikjoo, D., Warna, J., Irgum, K., Mikkola, J.-P. & Khokarale, S. G. (2022). Sustainable, highly selective, and metal-free thermal depolymerization of poly-(3-hydroxybutyrate) to crotonic acid in recoverable ionic liquids. Green Chemistry, 24(10), 4130-4139
Open this publication in new window or tab >>Sustainable, highly selective, and metal-free thermal depolymerization of poly-(3-hydroxybutyrate) to crotonic acid in recoverable ionic liquids
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2022 (English)In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 24, no 10, p. 4130-4139Article in journal (Refereed) Published
Abstract [en]

Valorization of renewable and biodegradable biopolymers to value added chemicals and green fuels is currently considered as an important research topic aiming at reducing the dependency on fossil derived feedstocks as well as their negative consequences on the environment. In this report, we are introducing an ionic liquid (IL) mediated, sustainable, and green synthesis of crotonic acid (CA) from poly-(3-hydroxybutyrate, PHB), a biopolymer derived from microbial fermentation. In this actual case, imidazolium cation comprising ILs have been used in the synthesis, where the influence of various reaction parameters such as reaction temperature and types of ILs as well as the amount of polymer, water, and IL in the reaction mixture were examined. The conversion of PHB to CA in IL took place by a base catalyzed depolymerization with formation of crotonyl terminated polymeric entities as intermediates, a mechanism that was confirmed by NMR analysis of the reaction mixtures sampled when the reactions were carried out at various temperatures. The rate of CA formation via the IL mediated base catalyzed depolymerization increased with increasing temperature in the tested interval, and 97% yield of CA was obtained after 90 min at 140 °C. The [EMIM][AcO] IL applied as solvent and catalyst is capable of completely depolymerizing PHB to CA in 5 h at 120 °C up to a polymer loading of 40 wt%. At higher loadings the depolymerization became incomplete, which is attributed to a deactivation of the IL due to hydrogen bonding interactions with the in situ formed CA, confirmed by NMR and DSC techniques. Since the depolymerization is base catalyzed, the only tested ILs that were able to form CA were based on acetate anions, whereas the less basic or neutral [EMIM][Cl] IL was found to be inactive. Finally, more than 90% of CA as well as [EMIM][AcO] IL were recovered in high purity by solvent extraction with brine (saturated aqueous NaCl) and 2-methyl tetrahydrofuran (2-Me-THF). Most importantly, here we introduce a sustainable, metal free, and single solvent based reaction approach for selective depolymerization of PHB to industrially valuable CA in basic and recoverable ILs.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2022
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-195103 (URN)10.1039/D2GC00621A (DOI)000792782700001 ()2-s2.0-85131448220 (Scopus ID)
Funder
Bio4EnergyKnut and Alice Wallenberg Foundation
Available from: 2022-05-23 Created: 2022-05-23 Last updated: 2023-03-24Bibliographically approved
Mavliutova, L., Munoz Aldeguer, B., Wiklander, J., Wierzbicka, C., Huynh, C. M., Nicholls, I. A., . . . Sellergren, B. (2021). Discrimination between sialic acid linkage modes using sialyllactose-imprinted polymers. RSC Advances, 11(36), 22409-22418
Open this publication in new window or tab >>Discrimination between sialic acid linkage modes using sialyllactose-imprinted polymers
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2021 (English)In: RSC Advances, E-ISSN 2046-2069, Vol. 11, no 36, p. 22409-22418Article in journal (Refereed) Published
Abstract [en]

Glycosylation plays an important role in various pathological processes such as cancer. One key alteration in the glycosylation pattern correlated with cancer progression is an increased level as well as changes in the type of sialylation. Developing molecularly-imprinted polymers (MIPs) with high affinity for sialic acid able to distinguish different glycoforms such as sialic acid linkages is an important task which can help in early cancer diagnosis. Sialyllactose with α2,6′vs.α2,3′ sialic acid linkage served as a model trisaccharide template. Boronate chemistry was employed in combination with a library of imidazolium-based monomers targeting the carboxylate group of sialic acid. The influence of counterions of the cationic monomers and template on their interactions was investigated by means of1H NMR titration studies. The highest affinities were afforded using a combination of Br−and Na+counterions of the monomers and template, respectively. The boronate ester formation was confirmed by MS and1H/11B NMR, indicating 1 : 2 stoichiometries between sialyllactoses and boronic acid monomer. Polymers were synthesized in the form of microparticles using boronate and imidazolium monomers. This combinatorial approach afforded MIPs selective for the sialic acid linkages and compatible with an aqueous environment. The molecular recognition properties with respect to saccharide templates and glycosylated targets were reported.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2021
National Category
Organic Chemistry Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-185760 (URN)10.1039/d1ra02274a (DOI)000667711300053 ()2-s2.0-85108896879 (Scopus ID)
Funder
EU, Horizon 2020, 722171, H2020-MSCA-ITN-2016
Available from: 2021-07-05 Created: 2021-07-05 Last updated: 2023-09-05Bibliographically approved
Christensen, M., Jablonski, P., Altermark, B., Irgum, K. & Hansen, H. (2021). High natural PHA production from acetate in Cobetia sp. MC34 and Cobetia marina DSM 4741T and in silico analyses of the genus specific PhaC2 polymerase variant. Microbial Cell Factories, 20(1), Article ID 225.
Open this publication in new window or tab >>High natural PHA production from acetate in Cobetia sp. MC34 and Cobetia marina DSM 4741T and in silico analyses of the genus specific PhaC2 polymerase variant
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2021 (English)In: Microbial Cell Factories, ISSN 1475-2859, E-ISSN 1475-2859, Vol. 20, no 1, article id 225Article in journal (Refereed) Published
Abstract [en]

Background: Several members of the bacterial Halomonadacea family are natural producers of polyhydroxyalkanoates (PHA), which are promising materials for use as biodegradable bioplastics. Type-strain species of Cobetia are designated PHA positive, and recent studies have demonstrated relatively high PHA production for a few strains within this genus. Industrially relevant PHA producers may therefore be present among uncharacterized or less explored members. In this study, we characterized PHA production in two marine Cobetia strains. We further analyzed their genomes to elucidate pha genes and metabolic pathways which may facilitate future optimization of PHA production in these strains.

Results: Cobetia sp. MC34 and Cobetia marina DSM 4741T were mesophilic, halotolerant, and produced PHA from four pure substrates. Sodium acetate with- and without co-supplementation of sodium valerate resulted in high PHA production titers, with production of up to 2.5 g poly(3-hydroxybutyrate) (PHB)/L and 2.1 g poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/L in Cobetia sp. MC34, while C. marina DSM 4741T produced 2.4 g PHB/L and 3.7 g PHBV/L. Cobetia marina DSM 4741T also showed production of 2.5 g PHB/L from glycerol. The genome of Cobetia sp. MC34 was sequenced and phylogenetic analyses revealed closest relationship to Cobetia amphilecti. PHA biosynthesis genes were located at separate loci similar to the arrangement in other Halomonadacea. Further genome analyses revealed some differences in acetate- and propanoate metabolism genes between the two strains. Interestingly, only a single PHA polymerase gene (phaC2) was found in Cobetia sp. MC34, in contrast to two copies (phaC1 and phaC2) in C. marina DSM 4741T. In silico analyses based on phaC genes show that the PhaC2 variant is conserved in Cobetia and contains an extended C-terminus with a high isoelectric point and putative DNA-binding domains.

Conclusions: Cobetia sp. MC34 and C. marina DSM 4741T are natural producers of PHB and PHBV from industrially relevant pure substrates including acetate. However, further scale up, optimization of growth conditions, or use of metabolic engineering is required to obtain industrially relevant PHA production titers. The putative role of the Cobetia PhaC2 variant in DNA-binding and the potential implications remains to be addressed by in vitro- or in vivo methods.

Place, publisher, year, edition, pages
BioMed Central, 2021
Keywords
Acetate, Cobetia spp, Genome, Halomonadacea, Halomonas spp, PHA, PhaC, PHB, PHBV, Polyhydroxyalkanoates
National Category
Microbiology in the medical area Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-190861 (URN)10.1186/s12934-021-01713-0 (DOI)000732951200001 ()2-s2.0-85121375372 (Scopus ID)
Available from: 2021-12-29 Created: 2021-12-29 Last updated: 2023-09-05Bibliographically approved
Shamshir, A., Dinh, N. P., Jonsson, T., Sparrman, T. & Irgum, K. (2020). Probing the retention mechanism of small hydrophilic molecules in hydrophilic interaction chromatography using saturation transfer difference nuclear magnetic resonance spectroscopy. Journal of Chromatography A, 1623, Article ID 461130.
Open this publication in new window or tab >>Probing the retention mechanism of small hydrophilic molecules in hydrophilic interaction chromatography using saturation transfer difference nuclear magnetic resonance spectroscopy
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2020 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1623, article id 461130Article in journal (Refereed) Published
Abstract [en]

The interactions and dynamic behavior of a select set of polar probe solutes have been investigated on three hydrophilic and polar commercial stationary phases using saturation transfer difference 1 H nuclear magnetic resonance (STD-NMR) spectroscopy under magic angle spinning conditions. The stationary phases were equilibrated with a select set of polar solutes expected to show different interaction patterns in mixtures of deuterated acetonitrile and deuterium oxide, with ammonium acetate added to a total concentration that mimics typical eluent conditions for hydrophilic interaction chromatography (HILIC). The methylene groups of the stationary phases were selectively irradiated to saturate the ligand protons, at frequencies that minimized the overlaps with reporting protons in the test probes. During and after this radiation, the saturation rapidly spreads to all protons in the stationary phase by spin diffusion, and from those to probe protons in contact with the stationary phase. Probe protons that have been in close contact with the stationary phase and subsequently been released to the solution phase will have been more saturated due to a more efficient transfer of spin polarization by the nuclear Overhauser effect. They will therefore show a higher signal after processing of the data. Saturation transfers to protons in neutral and charged solutes could in some instances show clear orientation patterns of these solutes towards the stationary phases. The saturation profile of formamide and its N-methylated counterparts showed patterns that could be interpreted as oriented hydrogen bond interaction. From these studies, it is evident that the functional groups on the phase surface have a strong contribution to the selectivity in HILIC, and that the retention mechanism has a significant contribution from oriented interactions.

Place, publisher, year, edition, pages
Elsevier, 2020
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-166941 (URN)10.1016/j.chroma.2020.461130 (DOI)000538809300003 ()32505268 (PubMedID)2-s2.0-85084336561 (Scopus ID)
Note

Originally included in thesis in manuscript form.

Available from: 2020-01-07 Created: 2020-01-07 Last updated: 2023-03-24Bibliographically approved
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