Tensile mechanical properties and hydraulic permeabilities of electrospun cellulose acetate fiber meshes Triantafyllos Stylianopoulos, 1 Maria Kokonou, 1 Stefanos Michael, 1 Antonia Tryfonos, 1 Claus Rebholz, 1 Andreani D. Odysseos, 2 Charalambos Doumanidis 1 1 Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia 1678, Cyprus 2 EPOS-Iasis R&D, Division of Biomedical Research, Nicosia 2028, Cyprus Received 19 February 2012; revised 27 June 2012; accepted 11 July 2012 Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jbm.b.32791 Abstract: The mechanical properties and hydraulic perme- abilities of biomaterial scaffolds play a crucial role in their ef- ficacy as tissue engineering platforms, separation processors, and drug delivery vehicles. In this study, electrospun cellu- lose acetate fiber meshes of random orientations were cre- ated using four different concentrations, 10.0, 12.5, 15.0, and 17.5 wt % in acetone or ethyl acetate. The tensile mechanical properties and the hydraulic permeabilities of these meshes were measured, and a multiscale model was employed to predict their mechanical behavior. Experimentally, the elastic modulus ranged from 3.5 to 12.4 MPa depending on the polymer concentration and the solvent. Model predictions agreed well with the experimental measurements when a fit- ted single-fiber modulus of 123.3 MPa was used. The model also predicted that changes in fiber alignment may result in a 3.6-fold increase in the elastic modulus for moderately aligned meshes and a 8.5-fold increase for highly align meshes. Hydraulic permeabilities ranged from 1.4 x 10 12 to 8.9 x 10 12 m 2 depending on polymer concentration but not the choice of solvent. In conclusion, polymer concentration, fiber alignment, and solvent have significant impact on the mechanical and fluid transport properties of electrospun cellulose acetate fiber meshes. V C 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B:000–000, 2012. Key Words: biomaterial scaffolds, multiscale simulation, stress/strain relationship, tissue engineering, separation processes How to cite this article: Stylianopoulos T, Kokonou M, Michael S, Tryfonos A, Rebholz C, Odysseos AD, Doumanidis C. 2012. Tensile mechanical properties and hydraulic permeabilities of electrospun cellulose acetate fiber meshes. J Biomed Mater Res Part B 2012:00B:000–000. INTRODUCTION Biomaterial scaffolds have a wide range of biomedical appli- cations, particularly in the fields of tissue engineering, in drug delivery, and in separation processes. In tissue engi- neering, biomaterials intend to replace native tissues in the human body in case of tissue damage or loss. For this rea- son, they must achieve not only biocompatibility but also functionality. Mechanical function, however, still remains a critical challenge for many tissues, such as blood vessels and heart valve leaflets. 1 Controlled release of drugs through po- rous membranes and separation processes such as size exclusion chromatography involve the transport of macromo- lecules and particles through the pores of the scaffolds. 2,3 Fluid velocity in such porous scaffolds is proportional to the hydraulic permeability, and thus convective transport depends on the permeability of the scaffolds. 4 Therefore, me- chanical properties and hydraulic permeabilities are crucial parameters that determine the applicability of biomaterials. Recently, electrospinning has emerged as a promising method for fabricating fibrous scaffolds for tissue engineer- ing applications such as blood vessels, anterior cruciate ligament, and cardiac tissue 5–8 and also for the formation of affinity membranes and scaffolds for the controlled release of drugs. 9–11 Electrospinning involves the applica- tion of a high voltage to eject a polymer fiber from solution and deposit it onto a grounded target. The size of electro- spun fibers can range from 100 nm to more than 10 lm depending on the polymer type, concentration, and the electrospinning conditions, while the orientation of the resulting mesh can be controlled by depositing the fibers onto a rotating target. 12–14 Cellulose acetate is the acetate ester of cellulose. Electro- spun cellulose acetate meshes have attracted attention in the last years because they have been reported to have good thermal stability and biocompatibility and exhibit chemical resistance. In addition, they do not cause any tox- icity, and they are biodegradable. 15 They can be dissolved in several organic solvents but show very low solubility in water. 16 As a result, electrospun cellulose acetate meshes have been used as antimicrobial membranes, 17 scaffolds for Additional Supporting Information may be found in the online version of this article. Correspondence to: T. Stylianopoulos; e-mail: tstylian@ucy.ac.cy or C. Doumanidis; e-mail: cdoumani@ucy.ac.cy Contract grant sponsor: Research Promotion Foundation of Cyprus; contract grant number: TEXNOLOGIA/YLIKA/0308(BIE)/05 (NanoTissue) V C 2012 WILEY PERIODICALS, INC. 1