The project approach to fabricate the devices combines cellulosic fibres (especially Lyocell fibres), polylactic acid (PLA) and bone-like apatite (hydroxyapatite, HAp) and the products will provide biomedical platforms that are ideal for bone tissue engineering application due to their biocompatibility and biodegradability coupled with low toxicity.
For tissue engineering, biodegradable materials in the form of fibers and yarns have attracted increasing attention since they provide a large surface area, thus desirable as a scaffold matrix material. In order to improve the formation or regeneration of living tissue, it is necessary to produce novel materials with good mechanical properties and form scaffolds in relation to their intended applications. Cellulosic fibres are promising especially for bone tissue engineering applications due to bone compatible mechanical properties in combination with good machinability and their commercial availability in a wide range of forms and shapes. Lyocell fibre is being specially selected since it represents an improved cost/performance profile compared to other cellulosic fibres like viscose and virtually all of the chemicals used in the production process are reclaimed, thus friendlier to the environment.
One of the key factors in tissue engineering is also to improve cell interaction with biologically active molecules in the very vicinity of bone tissue. The most studied method includes incorporating/embedding biologically active minerals, such as β-tricalciumphosphate and hydroxyapatite, into scaffold/matrix materials such as PLA and PHB. The problem with this system using these particles as filler is that the composites generally become too brittle to serve their intended use. Furthermore, the opportunity for tissue cells to interact with the particles is significantly reduced and cell adhesion to thus prepared composites is seen to be lower than expected. Better cell adhesion might be obtained by applying a mineral coating on a surface as well as novel design of scaffold through textile weaving technology. To our knowledge, only non-woven constructions have been used in order to form scaffolds from cellulosic fibres, but a number of textile technologies existed have the potential for other textile structures like wovens and knits.
In the project, monofilament fibers and multifilament hybrid yarns of Lyocell fibers and PLA containing HAp will be produced by melt-spinning process using the piston machine, that has several advantages compared to solution spinning, i.e. dry and wet spinning, because of more economical and ecofriendly route (high production speed and solvent-free process).In the following step, a weaving technology will be applied to fabricate novel woven textile scaffolds from the produced fibers and yarns that may provide ideal biodegradable platform for bone tissue engineering. As described above that the surface properties play an important role in determining how tissue cells respond to the textile scaffold, a surface apatite coating around the melt-spun fibers and yarns, which contain no mineral, will be also carried out as an attempt to accelerate/maximize a biomimetic process of HAp.
Apart from the textile scaffold of melt-spun fibers and yarns, another study will be initiated in parallel. The Lyocell fiber and PLA blends at various weight ratios will be processed to form bioresorbable composite films through melt-mixing and extrusion followed by electrospinning/coating HAp on the film surface so that insufficient mechanical strength (weakness and brittleness) and low cell adhesion of common biomaterials/HAp composites is increased and promoted. Finally, in vitro investigation using cell culture will be conducted to assess the biological performance of these textile scaffolds and bioresorbable composites.
The multi-disciplinary research and activities indispensable to this extensive project will be performed by using the competence and laboratory facilities at the School of Engineering to a large extent and in the Swedish School of Textiles at the University of Borås, in collaboration with the University of Oulu in Finland for biological assay. Lyocell fibres in various grades under brand name „Tencel‟ will be supported by Lenzing in Austria, the largest supplier of cellulose fibres to the world market.
The objective of this project is to obtain knowledge about the development of novel textile scaffolds and bioresorbable composite films from cellulosic fibre and biodegradable polymer with bone-like apatite as well as their processability in fiber melt-spinning and film melt-extrusion. In this project, the results may provide all the required end-product performance characteristics in order to rapidly scale up the products for applications. Therefore, the data also need to be investigated and evaluated in terms of large scale production. The outcomes from the projects will serve as a base for improving and extending applications of textiles scaffolds and composites as biomedical materials for bone tissue engineering.