| 1. |
- Arnebrant, Thomas, et al.
(author)
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Adsorption of chlorhexidine and black tea onto in vitro salivary pellicles, as studied by ellipsometry
- 2006
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In: European Journal of Oral Sciences. - : Wiley. - 0909-8836 .- 1600-0722. ; 114, s. 337-342
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Journal article (peer-reviewed)abstract
- The adsorption from 0.2% (w/w) chlorhexidine and black tea solutions onto an in vitro pellicle from whole unstimulated saliva on hydroxyapatite discs was studied by ellipsometry. It was found that chlorhexidine adsorbed to the pellicle causing a modification of the pellicle properties, leading to a subsequent increase in adsorption of salivary and black tea components. There was a distinct order of addition effect, whereby chlorhexidine followed by black tea gave an overall greater adsorption of components compared to black tea followed by chlorhexidine. This increase in adsorption gave a concomitant increase in colour or stain as measured by a reflectance chromameter. The increase in adsorbed amounts and stain was modified in part by the adsorption of salivary fractions between the chlorhexidine and black tea treatments. In all cases, the chlorhexidine and black tea modified pellicles were not readily removed by either phosphate or sodium dodecyl sulphate rinses. Thus, following chlorhexidine exposure, the accelerated adsorption of salivary and black tea components can ultimately lead to increased staining of the pellicle.
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| 2. |
- Arnebrant, Thomas, et al.
(author)
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Lubricating Properties of the Initial Salivary Pellicle
- 2003
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In: Biofouling (Print). - : Harwood Academic Publishers. - 0892-7014 .- 1029-2454. ; 19:6, s. 365-369
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Journal article (peer-reviewed)abstract
- The role of saliva in the oral cavity is manifold; an important function is to serve as lubricant between hard (enamel) and soft (mucosal) tissues. Intraoral lubrication is of crucial importance in order to maintain functions such as deglutition, mastication and the faculty of speech. A large number of people suffer from impaired salivary functions, displaying symptoms such as 'dry mouth'. This results in a need for methods to assess the lubricating properties of both native saliva and potential artificial saliva formulations. Here, normal as well as lateral forces, acting between adsorbed salivary films, have been measured for the first time by means of colloidal probe atomic force microscopy (AFM). It was found that the presence of salivary pellicles between hard surfaces reduces the friction coefficient by a factor of 20. This reduction of friction is consistent with the long-range purely repulsive nature of the normal forces acting between the salivary films. The lubricating mechanism is presumably based on a full separation of the sliding surfaces by the salivary films. The friction between salivary films has been investigated at normal loads that cover the clinical jaw closing forces, and it can be concluded that the lubricating properties are maintained within this load interval. The present study indicates the usefulness of colloidal probe AFM, which offers a direct and quantitative measure of lubrication at a molecular level, in the study of biotribological phenomena. In particular, the results obtained here may have implications for the development of saliva substitutes.
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| 3. |
- Boyd, Hannah, 1994-
(author)
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On the structure and mechanical properties of in vitro salivary pellicles
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Salivary pellicles display exceptional hydration and lubrication performance. At present, there are still gaps in the understanding of how this is achieved. The aim of this thesis was therefore to increase our knowledge on the mechanisms underlying these properties and deepen the understanding of how they are related to the composition and structure of pellicles, with a focus on those formed under in vitro conditions. This has applications ranging from the development of artificial saliva and lubricating coatings for biomedical applications to methodological approaches for initial testing of oral healthcare products. For this, we also focused on developing suitable methodological approaches for these studies, centering on atomic force microscopy, quartz crystal microbalance with dissipation monitoring, ellipsometry and neutron reflectometry techniques, to investigate in vitro and model salivary pellicles.First, we confirmed a two-layer structure for in vitro salivary pellicles and showed that the outer layer is mainly composed by the oral mucin MUC5B, but that it also contains other salivary components that enhance swelling and hydration. In the presence of bulk saliva, the outer layer also contains a reversibly and loosely bound fraction. This fraction increases the adhesiveness of the pellicle but unexpectedly has no significant effect on its lubrication performance. We also investigated the effect of mechanical confinement on model salivary pellicles by means of Neutron Reflectometry, revealing that at a pressure of 1 bar they are already completely compressed and dehydrated. Finally, with the aim to advance towards better oral healthcare products, we investigated the effect of nonionic and amphoteric surfactants on salivary pellicles, showing that they have a gentler effect on pellicle structure than the commonly employed anionic surfactants.
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| 4. |
- Carlsson, F, et al.
(author)
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Lysozyme adsorption to charged surfaces. A Monte Carlo study
- 2004
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In: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 108, s. 9871-
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Journal article (peer-reviewed)abstract
- Lysozyme adsorption to charged surfaces was studied by Monte Carlo simulations at different protein concentrations, protein net charges, ionic strengths, and surface charge densities. The lysozyme was represented by a hard sphere with embedded positive and negative surface charges parametrically dependent on the solution pH. A short-range attractive protein-protein potential was included to represent attractive non-Coulomb forces. The charged surface was described by a hard wall with embedded charges representing a mica surface. The protein adsorption was favored by high protein concentration, high protein net charge, low ionic strength, and high surface charge density. Nevertheless, adsorption appeared also for a weakly negatively charged protein to the negatively charged surface as a result of an electrostatically favorable protein orientation at the surface. While a multipole expansion including monopole and dipole moments only was insufficient to explain preferential orientation, an expansion including also quadrupole moments provided a satisfactory picture. Finally, it was found that the short-range attraction between the proteins increased the adsorbed amount, as well as the structure in the adsorbed protein layer. The adsorbed amounts obtained compared favorably with experimental results.
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| 5. |
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| 6. |
- Joiner, A, et al.
(author)
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Adsorption from black tea and red wine onto in vitro salivary pellicles studied by ellipsometry
- 2003
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In: European Journal of Oral Sciences. - : Blackwell Munksgaard. - 0909-8836 .- 1600-0722. ; 111, s. 417-422
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Journal article (peer-reviewed)abstract
- The adsorption of black tea and red wine components onto a pellicle-like protein layer formed in vitro by adsorption from whole unstimulated saliva on hydroxyapatite discs were studied by in situ ellipsometry. It was found that components from black tea readily adsorbed to the pellicle. Subsequent exposure to saliva led to further adsorption of salivary components to give an overall increase in the amounts adsorbed. The amounts adsorbed increased still further following a third tea and saliva exposure. Components of red wine gave significantly greater amounts of adsorption to the pellicle than black tea. The adsorption of components of black tea gave a concomitant increase in colour or stain as measured by a reflectance chromameter. In all cases, the black tea- and red wine-modified pellicles were not eluted by either phosphate buffer or sodium dodecyl sulphate (SDS) rinses. Thus, black tea and red wine components have been shown to have a profound effect on in vitro pellicle maturation, causing thickened layers of stained material to build up, which are not readily removed.
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| 7. |
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| 8. |
- Landström, K, et al.
(author)
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Competitive protein adsorption between ß-casein and ß-lactoglobulin during spray-drying: effect of calcium induced association
- 2003
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In: Food Hydrocolloids. - : Fairleigh Dickinson University Press. - 0268-005X .- 1873-7137. ; 17, s. 103-116
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Journal article (peer-reviewed)abstract
- Competitive adsorption between ß-casein and ß-lactoglobulin (ß-Lg) during spray-drying was studied by the new surface sensitive technique using fluorescence quenching of pyrene labelled protein at the powder surface. The difference in competitiveness of -casein when present as monomers and as associated into micellar like structures were studied. Results were compared with the adsorption of single proteins at the powder surface. The adsorption of monomeric ß-casein alone gave an apparent surface load of ≈1 mg/m2 at a protein concentration of 0.3% dry weight and then remained constant with an increasing protein concentration. In the presence of Ca2+, associated ß-casein gave a lower affinity adsorption than monomeric ß-casein and did not reach a plateau value, instead it continued to increase with an increasing protein concentration. ß-Lg showed a low-affinity adsorption during spray-drying compared to monomeric ß-casein, although not as low as associated ß-casein. Competitive adsorption between monomeric ß-casein and ß-Lg resulted in a higher apparent surface load of ß-casein than ß-Lg at both protein concentrations studied (total 0.3 and 3.3% dry weight). However, in an associated form ß-casein was less competitive than ß-Lg. At a low bulk protein concentration (0.3% dry weight) ß-Lg dominated the powder surface, whereas at a higher concentration (3.3% dry weight) there was little difference between the proteins. The results indicate that the competitiveness of a protein during spray-drying is highly influenced by the ability of the protein to attach and rearrange at the droplet's air–water interface during the spray-drying process
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