FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W464596222> ?p ?o ?g. }

• W464596222 abstract "(1→3)-β-D-glucans are a group of important glucose polymers, some of which are used commercially for wound healing (wound closure). A branched β-1,3 glucan preparation developed by Biotec Pharmacon (Soluble β-glucan, abbreviated SBG) obtained from S. cerevisiae was studied in the work. Although being water-soluble it tends to aggregate strongly in aqueous solution, especially at low temperatures. The physical properties of SBG, including the aggregation behaviour, depend on the properties of the individual polymer molecules, which must be accurately known, both from a fundamental perspective and for regulatory approval.The thesis not only investigated different methods to obtain the unaggregated single chain state of SBG and its physical properties, but also investigated the physical and chemical properties of the aggregated states.In the first part of the study, chemical derivatization (partial O-carboxymethylation) was used to investigate the single chain state of SBG and thereby obtain the molecular weight distribution. A major problem of carboxymethylation (CM) of β-(1,3)-glucan is the possibility for degradation (β-elimination) during the chemical reaction, resulting in underestimated Mw and Mn. Our results demonstrate that degradation is avoided provided the glucan is reduced with NaBH4 prior to carboxymethylation, and hence provide easy control of the degree of substitution (DS) values. SEC-MALLS analysis of CM-SBG showed a progressive loss of aggregates with increasing DS, and for a critical value (DS = 0.53) completely aggregate-free solutions were obtained, allowing accurate determination of the average molecular weight and molecular weight distributions of SBG by SEC-MALLS.In the second part of the study, organic solvents were investigated as SEC-MALLS eluents to possibly obtain fully dissolved SBG without chemical derivatization. Although previous literature [1-5] had shown that dimethyl sulphoxide (DMSO) in the absence or presence of 0.25 LiCl could be a good solvent and SEC-MALLS eluent for several branched (SBG-like) β-1,3-glucans, this study showed that SBG dissolved apparently well in DMSO, but some aggregated material was detected by SEC-MALLS even after heating. The aggregates dissolved completely when using 0.25 M LiCl in DMSO as solvent. However, technical difficulties (SEC column) prevented us from obtaining satisfactory SEC-MALLS data. An additional problem is the large variations in the refractive index increment (dn/dc)µ which have been reported in the literature. We obtained a value of 0.062 ml/g using the 100% recovery method in SEC-MALLS.As an alternative to DMSO, 0.5% LiCl in dimethyl acetamide (DMAc) was explored for the first time as solvent and SEC-MALLS eluent for SBG. This is based on the ability of DMAc/LiCl to dissolve other polysaccharides, notably cellulose. Since heating was required to obtain rapid dissolution, the rate of depolymerisation of SBG in DMAc/LiCl at high temperatures (70-105°C) was determined. This provided a basis for defining dissolution procedures for β-1,3 glucans using elevated temperatures with a minimum of degradation. The result of the investigation is a simple and reliable protocol for preparing unaggregated, fully dissolved and undegraded SBG in DMAc/LiCl, which is well suited as a standard analysis of the molecular weight distribution of SBG-like molecules without chemical derivatization.In the last part of the study, the properties of untreated (aggregated) SBG solutions were investigated in more detail. Dynamic light scattering (DLS) experiments showed that SBG in aqueous solution consists of free chains and particles with a very wide size distribution, depending on the temperature. Oscillatory rheometry demonstrated a typical gelling/melting behavior of SBG which was influenced by its concentration (2%- 20%) and temperatures. AFM images prepared from very dilute aqueous solution (1- 5μg/ml) analysis showed that SBG consists partly of triple helical species coexisting with larger aggregates as well as single chains." @default.
• W464596222 created "2016-06-24" @default.
• W464596222 creator A5076887322 @default.
• W464596222 date "2012-01-01" @default.
• W464596222 modified "2023-09-26" @default.
• W464596222 title "Chemical and physical characterization of bioactive soluble [1→3]- ßD-glucans [SBG] from Saccharomyces sp." @default.
• W464596222 hasPublicationYear "2012" @default.
• W464596222 type Work @default.
• W464596222 sameAs 464596222 @default.
• W464596222 citedByCount "0" @default.
• W464596222 crossrefType "dissertation" @default.
• W464596222 hasAuthorship W464596222A5076887322 @default.
• W464596222 hasConcept C158117686 @default.
• W464596222 hasConcept C175528265 @default.
• W464596222 hasConcept C178790620 @default.
• W464596222 hasConcept C179998833 @default.
• W464596222 hasConcept C184133267 @default.
• W464596222 hasConcept C184651966 @default.
• W464596222 hasConcept C185592680 @default.
• W464596222 hasConcept C188027245 @default.
• W464596222 hasConcept C2776123893 @default.
• W464596222 hasConcept C2776923573 @default.
• W464596222 hasConcept C2779679103 @default.
• W464596222 hasConcept C32909587 @default.
• W464596222 hasConcept C41008148 @default.
• W464596222 hasConcept C521977710 @default.
• W464596222 hasConcept C76155785 @default.
• W464596222 hasConceptScore W464596222C158117686 @default.
• W464596222 hasConceptScore W464596222C175528265 @default.
• W464596222 hasConceptScore W464596222C178790620 @default.
• W464596222 hasConceptScore W464596222C179998833 @default.
• W464596222 hasConceptScore W464596222C184133267 @default.
• W464596222 hasConceptScore W464596222C184651966 @default.
• W464596222 hasConceptScore W464596222C185592680 @default.
• W464596222 hasConceptScore W464596222C188027245 @default.
• W464596222 hasConceptScore W464596222C2776123893 @default.
• W464596222 hasConceptScore W464596222C2776923573 @default.
• W464596222 hasConceptScore W464596222C2779679103 @default.
• W464596222 hasConceptScore W464596222C32909587 @default.
• W464596222 hasConceptScore W464596222C41008148 @default.
• W464596222 hasConceptScore W464596222C521977710 @default.
• W464596222 hasConceptScore W464596222C76155785 @default.
• W464596222 hasLocation W4645962221 @default.
• W464596222 hasOpenAccess W464596222 @default.
• W464596222 hasPrimaryLocation W4645962221 @default.
• W464596222 hasRelatedWork W1498072590 @default.
• W464596222 hasRelatedWork W1522626495 @default.
• W464596222 hasRelatedWork W1994721405 @default.
• W464596222 hasRelatedWork W1997224256 @default.
• W464596222 hasRelatedWork W1999296390 @default.
• W464596222 hasRelatedWork W2022680963 @default.
• W464596222 hasRelatedWork W2043408078 @default.
• W464596222 hasRelatedWork W2057259464 @default.
• W464596222 hasRelatedWork W2064884609 @default.
• W464596222 hasRelatedWork W2069098819 @default.
• W464596222 hasRelatedWork W2071023720 @default.
• W464596222 hasRelatedWork W2073260081 @default.
• W464596222 hasRelatedWork W2079479333 @default.
• W464596222 hasRelatedWork W2092081752 @default.
• W464596222 hasRelatedWork W2092602316 @default.
• W464596222 hasRelatedWork W2212272653 @default.
• W464596222 hasRelatedWork W2489660766 @default.
• W464596222 hasRelatedWork W2530038007 @default.
• W464596222 hasRelatedWork W2979090153 @default.
• W464596222 hasRelatedWork W2989069682 @default.
• W464596222 isParatext "false" @default.
• W464596222 isRetracted "false" @default.
• W464596222 magId "464596222" @default.
• W464596222 workType "dissertation" @default.