Effect of hydration on thermodynamic, rheological and structural properties of mucin

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Effect of hydration on thermodynamic, rheological and structural properties of mucin

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dc.contributor.author Znamenskaya, Yana
dc.date.accessioned 2013-06-17T09:57:18Z
dc.date.available 2013-06-17T09:57:18Z
dc.date.issued 2013 en_US
dc.identifier.isbn 978-91-7104-513-3 en_US
dc.identifier.isbn 978-91-7104-514-0
dc.identifier.issn 1653-5383 en_US
dc.identifier.uri http://hdl.handle.net/2043/15514
dc.description.abstract Mucus, an adherent hydrated layer covering the epithelium, is found in all internal tracts of the body and plays an important role in animal and human life. One of the essential functions of mucus is protection of tissues against dehydration. A major component of mucus, forming the macromolecular matrix and also being responsible for its viscoelastic properties, is the glycoprotein mucin. Mucin is a complex molecule owing to the high molar mass, its polydispersity and high degree of glycosylation. This thesis is aimed to investigate how thermodynamic, structural and rheological properties of mucin are affected by hydration. The effect of hydration on thermodynamic properties of pig gastric mucin (PGM) and bovine submaxillary mucin (BSM) has been studied using sorption calorimetry and differential scanning calorimetry (DSC). The analysis of sorption isotherms shows higher water sorption capacity of PGM compared to BSM at relative humidity (RH) levels lower than about 78%. The value of the hydration enthalpy at zero water content at 25ºC for both biopolymers is close to -20 kJ/ mol. RH levels at which glass transition of both mucins occurs are shown to be between 60 and 70%. The RH at which glass transition occurs is weakly dependent on the temperature and mucin type. The phase diagram of PGM demonstrates two different glass transition regions: dependent and independent on hydration levels, respectively. In particular at mucin concentrations from 0 to 67 wt%, the glass transition occurs at a constant temperature of about –15ºC. At higher concentrations of mucin, the glass transition temperature (Tg) increases with increasing mucin concentrations. It is also demonstrated that the QCM-D technique can be used to obtain the water sorption isotherms of mucin films in particular and in general to monitor glass transitions in biopolymers. Hydration-induced changes of rheological properties of mucin films are investigated using a model-free approach. The ratio of G’/G’’ is evaluated as a function of relative humidity. Observed transitions from solid-like behaviour to liquid-like behaviour in mucin system occur in the same humidity range as that found in sorption calorimetric experiments. The structural properties of mucin have been studied using atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS). AFM indicates the presence of dumbbell as well as fiber-like structures in PGM samples. In the case of BSM samples, only fiber-like structures are observed. SAXS studies show three ranges of scattering vector q corresponding to different fractal dimensions in dilute PGM and BSM solutions. Dehydration-induced structural changes in PGM are demonstrated by a distinct appearance of peaks on scattering curves starting from 20 wt% of mucin. Structural changes at about 80 wt% obtained in SAXS at 25°C, correspond to mucin glass transition, and are in agreement with sorption calorimetry and DSC studies. Temperature-induced phase behaviour changes occur around 60-70°C at intermediate levels of hydration. A comparison between water sorption isotherms of BSM/chitosan multilayers and those of individual biopolymers shows that the water sorption capacity of BSM/chitosan multilayers is similar compared to that of individual biopolymers, although some differences exist. In particular, at low RH levels the water sorption capacity of multilayers is slightly higher compared to each biopolymer, however at high RH the multilayer films are less hydrated than individual biopolymers.
dc.format.extent 69
dc.language.iso eng en_US
dc.publisher Malmö University, Faculty of Health and Society
dc.relation.ispartofseries Doctoral Dissertation;2
dc.relation.haspart Znamenskaya, Y.; Sotres, J.; Engblom, J.; Arnebrant, T.; Kocherbitov, V. Effect of Hydration on Structural and Thermodynamic Properties of Pig Gastric and Bovine Submaxillary Gland Mucins. J. Phys. Chem. B. (2012), 116, 5047–5055.
dc.relation.haspart Znamenskaya, Y.; Sotres, J.; Gavryushov, S.; Engblom, J.; Arnebrant, T.; Kocherbitov, V. Water Sorption and Glass Transition of Pig Gastric Mucin Studied by QCM-D. J. Phys. Chem. B. (2013), 117, 2554−2563
dc.relation.haspart Znamenskaya, Y.; Sotres, J.; Arnebrant, T.; Kocherbitov, V. Hydration of Bovine Submaxillary Gland Mucin/Chitosan Multilayers Studied by QCMD. Manuscript
dc.relation.haspart Znamenskaya, Y.; Engblom, J.; Arnebrant, T.; Kocherbitov, V. Effects of Dehydration on Structural Properties and Phase Behaviour of Pig Gastric Mucin Evaluated by SAXS. Manuscript
dc.subject mucous gel
dc.subject mucus
dc.subject mucin
dc.subject PGM
dc.subject BSM
dc.subject BSM/chitosan multilayers
dc.subject hydration
dc.subject water sorption isotherm
dc.subject relative humidity
dc.subject water activity
dc.subject bound water
dc.subject enthalpy of hydration of biopolymer
dc.subject glass transition
dc.subject rheology
dc.subject phase diagram
dc.subject fiber-like structure
dc.subject dumbbell-like structure
dc.subject sorption calorimetry
dc.subject DSC
dc.subject QCM-D
dc.subject SAXS
dc.subject AFM
dc.subject.classification Technology en_US
dc.title Effect of hydration on thermodynamic, rheological and structural properties of mucin en_US
dc.type Doctoral Thesis en
dc.identifier.paperprint en_US
dc.contributor.department Malmö University. Faculty of Health and Society en_US
dc.contributor.department Malmö University. Biomedical Sciences (BMV) en_US
dc.description.other en_US
dc.subject.srsc Research Subject Categories::NATURAL SCIENCES en_US
dc.subject.srsc Research Subject Categories::TECHNOLOGY en_US
dc.subject.srsc Research Subject Categories::PHARMACY en_US
dcterms.type Doctoral Thesis, comprehensive summary
mahlocal.identifier.publit 3046
mahlocal.rights.oaType green
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