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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.

Different physico-chemical properties (eg adsorption kinetics, thickness, viscoelasticity, and mechanical stability) of adsorbed salivary pellicles depend on different factors, including the properties (eg charge, roughness, wettability, and surface chemistry) of the substratum. Whether these differences in the physico-chemical properties are a result of differences in the composition or in the organization of the pellicles is not known. In this work, the influence of substratum wettability on the composition of the pellicle was studied. For this purpose, pellicles eluted from substrata of different but well-characterized wettabilities were examined by means of sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that substratum hydrophobicity did not have a major impact on pellicle composition. In all substrata, the major pellicle components were found to be cystatins, amylases and large glycoproteins, presumably mucins. In turn, interpretation of previously reported data based on the present results suggests that variations in substratum wettability mostly affect the organization of the pellicle components.

Ellipsometry and mechanically assisted sodium dodecyl sulphate elution was utilized to study the adsorption of human serum albumin (HSA), human immunoglobulin G (IgG), and laminin-1, as well as competitive adsorption from a mixture of these proteins on spin-coated and sintered hydroxyapatite (HA) surfaces, respectively. The HA surfaces were characterized with respect to wettability and roughness by means of water contact angles and atomic force microscopy, respectively. Both surface types were hydrophilic, and the average roughness (Sa) and surface enlargement (Sdr) were lower for the sintered compared to the spin-coated HA surfaces. The adsorbed amounts on the sintered HA increased as follows: HSA < laminin-1 < IgG < the protein mixture. For the competitive adsorption experiments, the adsorbed fractions increased accordingly: HSA < laminin-1 < IgG on both types of HA substratum. However, a higher relative amount of HSA and laminin-1 and a lower relative amount of IgG was found on the spin-coated surfaces compared to the sintered surfaces. The effects observed could be ascribed to differences in surface roughness and chemical composition between the two types of HA substratum, and could have an influence on selection of future implant surface coatings.

This study investigated the effect of glow discharge treatment of titania surfaces on plasma protein adsorption, by means of ellipsometry and mechanically assisted SDS elution. The adsorption and film elution of three plasma proteins, viz. human serum albumin (HSA), human immunoglobulin G (IgG) and laminin-1, as well as competitive adsorption from a mixture of the three proteins, showed that the adsorbed amount of the individual proteins after 1 h increased in the order HSA

The adsorption of proteins from human whole saliva (HWS) onto silica and hydroxyapatite surfaces (HA) was followed by quartz crystal microbalance with dissipation (QCM-D) and ellipsometry. The influence of different surface properties and adsorption media (water and PBS) on the adsorption from saliva was studied. The viscoelastic properties of the salivary films formed on the solid surfaces were estimated by the use of the Voigt-based viscoelastic film model. Furthermore, the efficiency of SDS and delmopinol to elute the adsorbed salivary film from the surfaces was investigated at different surfactant concentrations. A biphasic kinetic regime for the adsorption from saliva on the silica and HA surfaces was observed, indicating the formation of a rigidly coupled first layer corresponding to an initial adsorption of small proteins and a more loosely bound second layer. The results further showed a higher adsorption from HWS onto the HA surfaces compared to the silica surfaces in both adsorption media (PBS and water). The adsorption in PBS led to higher adsorbed amounts on both surfaces as compared to water. SDS was found to be more efficient in removing the salivary film from both surfaces than delmopinol. The salivary film was found to be less tightly bound onto the silica surfaces since more of the salivary film could be removed with both SDS and delmopinol compared to that from the HA surface. When adsorption took place from PBS the salivary layer formed at both surfaces seemed to have a similar structure, with a high energy dissipation implying that a softer salivary layer is built up in PBS as opposed to that in water. Furthermore, the salivary layers adsorbed from water solutions onto the HA were found to be softer than those on silica.

The salivary film, denoted the pellicle, formed on oral surfaces is of great importance for oral health and comfort. The present study describes mechanically-assisted sodium dodecyl sulphate (SDS) elution of the in vivo pellicle formed on human enamel and visualisation of the desorbed pellicle proteins using two-dimensional gel electrophoresis (2-DE). To verify this removal of the pellicle, a combined mechanical and surfactant procedure was additionally performed on an in vitro pellicle formed on human enamel, and the effectiveness was validated by mechanical removal in combination with HCl. As indicated by protein quantitation and one dimensional gel electrophoresis, rubbing with polyamide fibre pellets soaked in a 0.5% SDS solution was optimal for completely removing the adsorbed proteins from the enamel surface, and yet provided separation of the proteins by 2-DE to enable identification in future studies.

In situ ellipsometry was employed to study adsorption from human palatal saliva (HPalS) in terms of dependence on surface wettability and saliva concentration (

The aim of this paper was to elucidate the mechanisms behind salivary lubrication with special emphasis on the lubricity of three key components of the pellicle, viz human acidic proline-rich protein 1 (PRP-1), human statherin and bovine submaxillary mucin (BSM). The lubricating properties of the proteins have been assessed by means of colloidal probe atomic force microscopy, and are discussed in relation to their adsorption behaviour. To various extents, the proteins investigated all showed a lubricating effect when adsorbed to silica surfaces. For comparable concentrations, PRP-1 was found to have a more pronounced lubricating effect than BSM, which in turn showed a higher lubricity than statherin. The relative lubricity is in accordance with previously reported relative adsorbed amounts of the three proteins, within the investigated concentration interval. It is concluded that PRP-1 has the highest lubricating capacity as a pure fraction among the preparations investigated, and that the lubricating effect of PRP-1 as a pure fraction is notably large as compared to the lubricity of human whole saliva.