Unilever Discover, Colworth Science Park, Sharnbrook, Bedfordshire, United Kingdom.
Colloids Surf B Biointerfaces. 2010 May 1;77(1):31-9. doi: 10.1016/j.colsurfb.2009.12.022. Epub 2010 Jan 13.
Salivary films coating oral surfaces are critically important for oral health. This study focuses on determining the underlying nature of this adsorbed film and how it responds to departures from physiological conditions due to changes in ionic strength. Under physiological conditions, it is found that pre-adsorbed in vitro salivary film on hydrophobic surfaces is present as a highly hydrated viscoelastic layer. We follow the evolution of this film in terms of its effective thickness, hydration and viscoelastic properties, as well as adsorbed mass of proteins, using complementary surface characterisation methods: a Surface Plasmon Resonance (SPR) and a Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). Our results support a heterogeneous model for the structure of the salivary film with an inner dense anchoring layer and an outer highly extended hydrated layer. Further swelling of the film was observed upon decreasing the salt concentration down to 1mM NaCl. However, upon exposure to deionised water, a collapse of the film occurs that was associated with the loss of water contained within the adsorbed layer. We suggest that the collapse in deionised water is driven by an onset of electrostatic attraction between different parts of the multi-component salivary film. It is anticipated that such changes could also occur when the oral cavity is exposed to food, beverage, oral care and pharmaceutical formulations where drastic changes to the structural integrity of the film is likely to have implications on oral health, sensory perception and product performance.
唾液膜覆盖口腔表面对于口腔健康至关重要。本研究旨在确定该吸附膜的本质及其对离子强度变化导致的生理条件偏离的反应。在生理条件下，研究发现疏水表面上预先吸附的体外唾液膜以高度水合的粘弹性层形式存在。我们使用互补的表面特征化方法，即表面等离子体共振（SPR）和石英晶体微天平耗散监测（QCM-D），来跟踪该膜在有效厚度、水合和粘弹性特性以及蛋白质吸附质量方面的演变。我们的结果支持唾液膜结构的多相模型，其中包含一个内部致密的锚定层和一个外部高度伸展的水合层。当盐浓度降低至 1mM NaCl 时，观察到膜进一步溶胀。然而，当暴露于去离子水时，膜发生坍塌，这与吸附层内所含水分的损失有关。我们认为，在去离子水中的坍塌是由多组分唾液膜不同部分之间的静电吸引引起的。预计当口腔暴露于食物、饮料、口腔护理和药物制剂时，也会发生这种变化，因为膜的结构完整性的剧烈变化可能会对口腔健康、感官感知和产品性能产生影响。
