Photoembossing for Surface Texturing of Films and Fibres for Biomedical Applications
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Photoembossing for Surface Texturing of Films and Fibres for Biomedical Applications Nanayaa Freda Hughes-Brittain1, Olivier T. Picot1, Lin Qiu1, Carlos Sanchez2 , Ton Peijs1,3 and Kees Bastiaansen3,1 1
School of Engineering and Material Science. Centre for Material Research, Queen Mary University of London, London, United Kingdom 2 Departmento de Fisica de la Materia Condensada. Faculta de Ciencias, Universidad de Zaragoza, Zaragoza, Spain; 3
Faculty of Chemistry and Chemical Engineering, Eindhoven University, Eindhoven, Netherlands. ABSTRACT Photoembossing is a technique used to create relief structures using a patterned contact photo-mask exposure and a thermal development step. Typically, the photopolymer consists of a polymer binder and a monomer in a 1/1 ratio together with a photo-initiator which results in a solid and non-tacky material at room temperature. Here, new mixtures for photoembossing are presented which are potentially biocompatible. A polymer binder such as poly (methyl methacrylate) with triacrylate monomer and biocompatible photo-initiator Irgacure 369 is used. Photopolymer films produced are successfully embossed with height of relief structures controlled by UV dosage and developing temperature. Furthermore, the photopolymer blend is electrospun to form fibres with diameters of 5 μm which are then photoembossed. The photoembossed fibres showed homogenous reproducible surface textures. Biocompatibility is evaluated by culturing human umbilical vein endothelial cells (HUVECs) on films of this photopolymer blend. The study shows that photoembossing is a feasible method of producing surface texturing on both films and electrospun fibres for tissue engineering applications. INTRODUCTION Surface texturing of polymers has been employed in numerous applications including biosensors, cell growth, in-situ cavity fillers, microelectronics and micro-optical display element [1-4]. Various techniques have been used to create these micro- and nano-relief structures including hot embossing, cast-moulding and lithography [5-7]. In hot embossing, a heated polymer film is pressed against a master mould to generate the relief structures [7, 8]. In cast moulding, a polymer precursor is poured into a mould and allowed to cure to form an inverse replica of the mould [5]. Photolithographic techniques usually require the use of a mask and photo-resist [9]. The mask is placed in close proximity of the photo-resist and is UV-irradiated. This exposure changes the solubility of the photo-resist and a wet-etching step is then used to produce the relief structure [9]. Photoembossing is a new technique that creates relief structures in thin films and this technique eliminates the use of a wet-etching step i.e. the relief structures are formed upon heating (Fig. 1) [10]. Moreover, exposure can be performed with a simple contact mask which is possible because the photo-resist is a non-tacky solid at room temperature. Photoembossing uses
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a mixture of a multifunctional monomer, a polymeric binder and a photo-initiator.
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