DSM Non-Biofouling Coatings: A stealth approach to the fighting biofilms

DSM has developed and markets a variety of hydrophilic UV curable coatings. These hydrophilic coatings include ComfortCoat lubricous coatings and (biocidal) antimicrobial lubricous coatings for both catheters and guide wires, as well as newly developed VitroStealth non biofouling coatings. In this paper we will highlight the technological and clinical benefits of our entire UV coatings platform and principally the novel non-biofouling technology. For our Non-fouling coatings we will demonstrate dramatic reduction in protein adsorption and cellular (microbial and blood) adhesion. Introduction: Non-fouling synthetic surfaces are highly desired for the development of biocompatible medical implants, biosensors and a diverse range of non-biomedical applications. The notion ‘non-fouling’ is generally used to characterize surfaces that, in contact with a biological fluid, resist unintended accumulation of biological entities, which may lead to, for example, the formation of a biofilm. Upon exposure of a synthetic surface to biological media, the initial event is the rapid adsorption of macromolecular moieties, forming a so-called conditioning film for the subsequent adhesion of other molecular and cellular entities. A number of studies, following various strategies, have focused on the surface modification of materials to prevent the initial and non-specific adsorption of macromolecular components, notably proteins, biological cells and microorganisms. One approach to render surfaces non-fouling, is the adsorption or covalent grafting of hydrophilic polymer chains or oligomer with brush-like structures. The most widely utilized polymer for achieving non-fouling properties and improved biocompatibility both in-vivo and in-vitro is poly(ethylene glycol) (PEG). A number of strategies for preparing brush-like PEG surfaces involve for example, adsorption of block copolymers with a non-adsorbing and a strongly adsorbing block, cross linking of star-shaped PEG polymers, end-grafting of reactive PEG chains, and transferred Langmuir-Blodgett films. However, the majorities of these methods are substrate-specific and require tailored steps of surface preparation and therefore a generally applicable grafting method is desirable. In the aforementioned studies, the desired interfacial properties were attained by a monomolecular layer grafted to a substrate, yielding coatings that are susceptible to mechanical damage, resulting in a localized loss of nonfouling performance. Thereby, the use of functional monolayers in everyday applications is limited and there is an ongoing need to develop coatings that combine the desired surface functionality of densely grafted monolayers with mechanical and (bio)-chemical robustness. In this paper we present the results of a study pertaining to the inhibition of protein adsorption and cellular adhesion on robust coatings with a high density of grafted hydrophilic polymers. The coating formulations consist of colloidal silica nano-particles with reactive acrylate groups and hydrophilic PEG chains, suspended in a methanol – water mixture. After application of the coating and evaporation of the solvent, the particles are cross-linked by exposure to ultraviolet (UV) radiation. Figure 1. Schematic representation of silica oxide nano-particles surface modified with acrylate groups (Step 1), grafted with mPEG chains (Step 2) and followed by coating application and photopolymerization (Step 3). Upon contact of the cross-linked coating with water, the PEG chains at the surface become hydrated and swell, providing a brush-like structure at the surface, as can be seen in figure 1.