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Silicone hydrogel contact lenses, which have been a major advance in the field of vision correction, require surface modification or coatings for comfort and biocompatibility. While current coatings show adequate clinical performance, advanced coatings may improve the biocompatibility of contact lenses further by reducing biofouling and related adverse clinical events. Here, we have produced coatings on Lotrafilcon A contact lenses by deposition of a thin film of allylamine plasma polymer (ALAPP) as a reactive interlayer for the high density grafting of poly(ethylene oxide) dialdehyde (PEO(ALD) 2 ), which had previously shown complete resistance to protein adsorption in vitro . The performance of these contact lenses was evaluated in a controlled clinical study over 6 h using Focus ® Night and Day™ (also known as Air Optix ® Night & Day ® ) contact lenses as control lenses. Surface modified lenses were characterised by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) before and after wear. Clinical data showed a high level of biocompatibility of the PEO coated lenses equivalent to control lenses. Surface analysis of worn contact lenses demonstrated that the high density PEO coating is effective in reducing biofouling in vivo compared to control lenses, however small amounts of protein deposits were still detected on all worn contact lenses. This study highlights that elimination of biofouling in vivo can be much more demanding than in vitro and discusses issues that are important for the analysis of worn contact lenses as well as the design of improved contact lenses.

Real-time control over and reversibility of biomolecule–surface interactions at interfaces is an increasingly important goal for a range of scientific fields and applications. The field of stimuli-responsive, smart or switchable systems has generated much research interest due to its potential to attain unprecedented levels of control over biomolecule adsorption processes and interactions at engineered interfaces,including the control over reversibility of adsorption. Advances in this field are particularly relevant to applications in the areas of biosensing, chromatography, drug delivery and regenerative medicine. The control over biomolecule adsorption and desorption processes at interfaces is often used to control subsequent events such as cell–surface interactions. Considerable research interest has been directed at systems that can be reversibly switched between interacting and non-interacting states and used thus for switching, on and off, bio-interfacial interactions such as protein adsorption. Such switchable coatings often incorporate features such as temporal resolution, spatial resolution and reversibility. Here were view recent literature on switchable coatings that employ stimuli such as light, temperature, electricpotential, pH and ionic strength to control protein adsorption/desorption and cell attachment/detachmenten route to the development of next-generation smart bio-interfaces. Refereed/Peer-reviewed