Full length article Electrostatic flocking of chitosan fibres leads to highly porous, elastic and fully biodegradable anisotropic scaffolds Elke Gossla a , Robert Tonndorf b , Anne Bernhardt a , Martin Kirsten b , Rolf-Dieter Hund b , Dilibar Aibibu b , Chokri Cherif b , Michael Gelinsky a,⇑ a Centre for Translational Bone, Joint and Soft Tissue Research, University Hospital and Medical Faculty, Technische Universität Dresden, Germany b Institute of Textile Machinery and High Performance Material Technology, Technische Universität Dresden, Germany article info Article history: Received 17 March 2016 Received in revised form 2 August 2016 Accepted 16 August 2016 Available online xxxx Keywords: Tissue engineering Chitosan Chitosan fibre Flock technology Biodegradable scaffold abstract Electrostatic flocking – a common textile technology which has been applied in industry for decades – is based on the deposition of short polymer fibres in a parallel aligned fashion on flat or curved substrates, covered with a layer of a suitable adhesive. Due to their highly anisotropic properties the resulting velvet- like structures can be utilised as scaffolds for tissue engineering applications in which the space between the fibres can be defined as pores. In the present study we have developed a fully resorbable compression elastic flock scaffold from a single material system based on chitosan. The fibres and the resulting scaf- folds were analysed concerning their structural and mechanical properties and the biocompatibility was tested in vitro. The tensile strength and Young’s modulus of the chitosan fibres were analysed as a func- tion of the applied sterilisation technique (ethanol, supercritical carbon dioxide, c-irradiation and auto- claving). All sterilisation methods decreased the Young’s modulus (from 14 GPa to 6–12 GPa). The tensile strength was decreased after all treatments – except after the autoclaving of chitosan fibres submerged in water. Compressive strength of the highly porous flock scaffolds was 18 ± 6 kPa with a elastic modulus in the range of 50–100 kPa. The flocked scaffolds did not show any cytotoxic effect during indirect or direct culture of human mesenchymal stem cells or the sarcoma osteogenic cell line Saos-2. Furthermore cell adhesion and proliferation of both cell types could be observed. This is the first demonstration of a fully biodegradable scaffold manufactured by electrostatic flocking. Statement of Significance Most tissues possess anisotropic fibrous structures. In contrast, most of the commonly used scaffolds have an isotropic morphology. By utilising the textile technology of electrostatic flocking, highly porous and clearly anisotropic scaffolds can be manufactured. Flocking leads to parallel aligned short fibres, glued on the surface of a substrate. Such structures are characterised by a high and adjustable porosity, accompanied by distinct stiffness in fibre direction. The present article describes for the first time a fully biodegradable flock scaffold, solely made of chitosan. Utilisation of only one material for manufacturing of flock substrate, adhesive and fibres allow a uniform degradation of the whole construct. Such a new type of scaffold can be of great interest for a variety of biomedical applications. Ó 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. 1. Introduction Scaffolds for tissue engineering (TE) applications have to meet different requirements. On the one hand high and open porosity of the constructs facilitates cell migration and integration, nutrient and waste transfer and provides space for the generation of extra- cellular matrix [1,2]. On the other hand a certain mechanical strength of scaffolds is indispensable to endure biomechanical loads in the defect site. Classical porous scaffolds with isotropic structure (e.g. freeze-dried sponges, porous ceramics) mostly exhi- bit considerably decreasing mechanical strength with increasing porosity. Some years ago the electrostatic flocking technique was already used for the generation of anisotropic fibrous scaffolds [3]. Flock scaffolds provide high porosity and good mechanical properties due to the parallel alignment of the fibres perpendicular http://dx.doi.org/10.1016/j.actbio.2016.08.022 1742-7061/Ó 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: michael.gelinsky@tu-dresden.de (M. Gelinsky). Acta Biomaterialia xxx (2016) xxx–xxx Contents lists available at ScienceDirect Acta Biomaterialia journal homepage: www.elsevier.com/locate/actabiomat Please cite this article in press as: E. Gossla et al., Electrostatic flocking of chitosan fibres leads to highly porous, elastic and fully biodegradable anisotropic scaffolds, Acta Biomater. (2016), http://dx.doi.org/10.1016/j.actbio.2016.08.022