| 1. |
- Cukkemane, Nivedita, et al.
(författare)
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Anti-adherence and bactericidal activity of sphingolipids against Streptococcus mutans
- 2015
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Ingår i: European Journal of Oral Sciences. - : John Wiley & Sons. - 0909-8836 .- 1600-0722. ; 123:4, s. 221-227
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the anti-biofilm activity of sphingosine, phytosphingosine (PHS), and sphinganine for: (i) anti-adherence activity on hydroxyapatite (HA) surfaces; and (ii) bactericidal activity on different Streptococcus mutans phenotypes (i.e. planktonic cells and cells from a disrupted biofilm). For this, HA discs treated with sphingolipids were incubated with S. mutans and the number of adherent cells was evaluated by both culture and confocal microscopy. Sphinganine strongly inhibited bacterial adherence by 1000-fold compared with an untreated surface. Phytosphingosine and sphingosine inhibited bacterial adherence by eight- and five-fold, respectively, compared with an untreated surface. On saliva-coated HA, sphinganine and PHS inhibited bacterial adherence by 10-fold. Bactericidal activity of sphingolipids was evaluated by culture. For biofilms, the strongest bactericidal activity was exhibited by sphingosine compared with PHS and sphinganine. At a concentration of 12.5 μg ml−1, PHS and sphingosine were profoundly effective against planktonic and disrupted biofilms; and sphinganine reduced the number of cells in planktonic form by 100-fold and those derived from a disrupted biofilm by 1000-fold. Atomic force microscopy studies suggested that mechanical stability does not appear to be a factor relevant for anti-fouling activity. The results suggest that sphingolipids may be used to control oral biofilms, especially those loaded with S. mutans.
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| 2. |
- Dahlstrom, M., et al.
(författare)
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Affinity states of biocides determine bioavailability and release rates in marine paints
- 2015
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Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 31:2, s. 201-210
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Tidskriftsartikel (refereegranskat)abstract
- A challenge for the next generation marine antifouling (AF) paints is to deliver minimum amounts of biocides to the environment. The candidate AF compound medetomidine is here shown to be released at very low concentrations, ie ng ml(-1) day(-1). Moreover, the release rate of medetomidine differs substantially depending on the formulation of the paint, while inhibition of barnacle settlement is independent of release to the ambient water, ie the paint with the lowest release rate was the most effective in impeding barnacle colonisation. This highlights the critical role of chemical interactions between biocide, paint carrier and the solid/aqueous interface for release rate and AF performance. The results are discussed in the light of differential affinity states of the biocide, predicting AF activity in terms of a high surface affinity and preserved bioavailability. This may offer a general framework for the design of low-release paint systems using biocides for protection against biofouling on marine surfaces.
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| 3. |
- Delvar, Alice, et al.
(författare)
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Interaction of polyelectrolytes with salivary pellicles on hydroxyapatite surfaces under erosive acidic conditions
- 2015
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 38:7, s. 21610-21618
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Tidskriftsartikel (refereegranskat)abstract
- The modification of acidic beverage formulations with food-approved, nonhazardous substances with antierosive properties has been identified as a key strategy for counteracting the prevalence of dental erosion, i.e., the acid-induced dissolution of hydroxyapatite (HA, the main mineral component of tooth surfaces). While many of such substances have been reported, very little is known on how they interact with teeth and inhibit their acid-induced dissolution. With the aim of filling this gap in knowledge, we have studied under acidic conditions the interaction between two polyelectrolytes of differing ionic character, carboxymethyl cellulose (CMC) and chitosan, and saliva-coated hydroxyapatite, i.e., a model for the outer surface of teeth. These studies were performed by means of ellipsometry, quartz crystal microbalance with dissipation monitoring, and atomic force microscopy. We also studied, by means of pH variations, how dissolution of saliva-coated HA is affected by including these polyelectrolytes in the erosive solutions. Our results confirm that salivary films protect HA from acid-induced dissolution, but only for a limited time. If the acid is modified with CMC, this polyelectrolyte incorporates into the salivary films prolonging in time their protective function. Eventually, the CMC-modified salivary films are removed from the HA surfaces. From this moment, HA is continuously coated with CMC, but this offers only a weak protection against erosion. When the acid is modified with the cationic chitosan, the polyelectrolyte adsorbs on top of the salivary films. Chitosan-modified salivary films are also eventually replaced by bare chitosan films. In this case both coatings offer a similar protection against HA dissolution, which is nevertheless notably higher than that offered by CMC.
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| 4. |
- Valentijn-Benz, Marianne, et al.
(författare)
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Sphingoid Bases Inhibit Acid-Induced Demineralization of Hydroxyapatite
- 2015
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Ingår i: Caries Research. - : S. Karger. - 0008-6568 .- 1421-976X. ; 49:1, s. 9-17
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Tidskriftsartikel (refereegranskat)abstract
- Calcium hydroxyapatite (HAp), the main constituent of dental enamel, is inherently susceptible to the etching and dissolving action of acids, resulting in tooth decay such as dental caries and dental erosion. Since the prevalence of erosive wear is gradually increasing, there is urgent need for agents that protect the enamel against erosive attacks. In the present study we studied in vitro the anti-erosive effects of a number of sphingolipids and sphingoid bases, which form the backbone of sphingolipids. Pretreatment of HAp discs with sphingosine, phytosphingosine (PHS), PHS phosphate and sphinganine significantly protected these against acid-induced demineralization by 80 ± 17%, 78 ± 17%, 78 ± 7% and 81 ± 8%, respectively (p < 0.001). On the other hand, sphingomyelin, acetyl PHS, octanoyl PHS and stearoyl PHS had no anti-erosive effects. Atomic force measurement revealed that HAp discs treated with PHS were almost completely and homogeneously covered by patches of PHS. This suggests that PHS and other sphingoid bases form layers on the surface of HAp, which act as diffusion barriers against H+ ions. In principle, these anti-erosive properties make PHS and related sphingosines promising and attractive candidates as ingredients in oral care products.
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