Please cite this article in press as: Rodríguez, K., et al. Electrospun nanoﬁbrous cellulose scaffolds with controlled microarchitecture. Carbohydrate Polymers (2013), http://dx.doi.org/10.1016/j.carbpol.2012.12.037 ARTICLE IN PRESS G Model CARP-7304; No. of Pages 7 Carbohydrate Polymers xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Carbohydrate Polymers jo u rn al hom epa ge: www.elsevier.com/locate/carbpol Electrospun nanoﬁbrous cellulose scaffolds with controlled microarchitecture Katia Rodríguez a , Johan Sundberg b , Paul Gatenholm b,c , Scott Renneckar a,d,∗ a Department of Materials Science, Virginia Tech, Blacksburg, VA 24060, USA b Wallenberg Wood Science Center, Department of Chemical and Biological Engineering, Chalmers University of Technology, Goteborg SE41296, Sweden c School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA 24060, USA d Department of Sustainable Biomaterials, Virginia Tech, 230 Cheatham Hall, Blacksburg, VA 24060, USA a r t i c l e i n f o Article history: Received 1 August 2012 Received in revised form 20 November 2012 Accepted 14 December 2012 Available online xxx Keywords: Cellulose Scaffold Porosity Hydroxyapatite Bone regeneration Laser a b s t r a c t Introducing porosity in electrospun scaffolds is critical to improve cell penetration and nutrient diffusion for tissue engineering. Nanoﬁbrous cellulose scaffolds were prepared by electrospinning cellulose acetate (CA) followed by saponiﬁcation to regenerate cellulose. Using a computer-assisted design approach, scaffolds underwent laser ablation resulting in pores with diameters between 50 and 300 m with- out damaging or modifying the surrounding scaffold area. A new mineralization method was employed in conjunction with microablation using commercial phosphate buffered saline (PBS) to soak car- boxymethylcellulose surface-modiﬁed electrospun scaffolds. The resulting crystals within the scaffold on the interior of the pore had a calcium to phosphate ratio of 1.56, similar to hydroxyapatite. It was observed that porosity of the cellulose scaffolds enhanced osteoblast cell attachment at the edge of the pores, while mineralization enhanced overall cell density. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction Nanoﬁbrous electrospun materials have been successfully used to mimic ultraﬁne textured extracellular matrix (ECM) for tissue engineering applications (Li, Laurencin, Ctaerson, Tuan, & Ko, 2002). However, cells live in a complex mixture of pores and ridges with architectures that go beyond the simple nonwoven mesh of elec- trospun ﬁbers (Stevens & George, 2005). Pores positively inﬂuence tissue bridging by allowing inward diffusion of growth factors and ECM proteins, and outward diffusion of waste products (Karande, Ong, & Agrawal, 2004). Up to this point, micro- and macroporos- ity has been difﬁcult to fabricate directly, limited to solid free form (SFF) fabrication techniques (Hollister, 2005). SFF techniques have made remarkable progress enabling scaffold design and fabrication, as 3D bioplotters or layered sintering techniques have reproduced biological structures directly from computed tomography (CT) scan images (Hollister, 2005). These designs inherently have the porosity required for mass transport, enabling required oxygen gra- dients, enhancing cell seeding and cell clustering, providing cell direction and integration paths, and optimized mechanical prop- erties based on a given porosity restraint. These controlled designs have shown improvement over non-controlled porogen leaching ∗ Corresponding author at: Department of Sustainable Biomaterials, Virginia Tech, Blacksburg, VA 24060, USA. Tel.: +1 540 231 7100; fax: +1 540 231 8176. E-mail address: srenneck@vt.edu (S. Renneckar). methods where salt, wax, or some other material imbedded in the scaffold is removed after fabrication (Malda et al., 2004). However, there is a trade-off using SFF methods as the micro- to macroscale scaffold structure can be designed as a perfect mimic, there is lit- tle control over the nano- to microscale features of the scaffold. This scale is important because this level of architecture is what cells actually “see”. Supporting this hypothesis, Chen, Smith and Ma (2006) illustrated that nanoﬁbers created by liquid phase sepa- ration of poly (l-lactic acid) deposited by reverse SFF enhanced cell growth and scaffold uniformity. Electrospinning of biocompatible polymers is advantageous over phase separation techniques because of the control of ﬁber characteristics such as diameter and orientation of the nanoﬁbrous mat. It is well documented that spinning biocompatible polymers, like collagen (Buttafoco et al., 2006) and polylactic acid (Zong et al., 2005), from solutions under electric ﬁelds create ﬁbers with nanoscale dimensions to serve as tissue scaffolds. Polylactic acid is relatively hydrophobic and requires modiﬁcation to enhance wet- ting characteristics for cell seeding and cell adhesion (Grafahrend et al., 2011). Nanocellulose biomaterials have history in biomedical applications as material for wound healing (Czaja, Krystynowicz, Bielecki, & Brown, 2006a; Czaja, Young, Kawecki, & Brown, 2006b) and recently have shown promising results in the tissue engineer- ing ﬁeld (Bodin et al., 2010; Svensson et al., 2005). Cellulose is a hydrophilic material, but insoluble in water because of extensive hydrogen bonding network. When degraded through hydroly- sis, cellulose forms glucose, making the degradation products 0144-8617/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.carbpol.2012.12.037